Pathogenesis of acute graft‐versus‐host disease: from intestinal microbiota alterations to donor T cell activation

Acute graft‐versus‐host disease (aGVHD) is a major life‐threatening complication of allogeneic haematopoietic cell transplantation (allo‐HCT). Here we discuss the aGVHD pathophysiology initiated by multiple signals that cause alloreactive T‐cell activation. The outcome of such donor T‐cell activation is influenced by T‐cell receptor‐signal strength, anatomical location, co‐stimulatory/co‐inhibitory signals and differentiation stage (naive, effector/memory) of T‐cells. Additionally, cross‐priming of T cells to antigens expressed by pathogens can contribute to aGVHD‐mediated tissue injury. In addition to the properties of donor T‐cell activation, highly specialized tissue resident cell types, such as innate lymphoid cells, antigen‐presenting cells, immune regulatory cells and various intestinal cell populations are critically involved in aGVHD pathogenesis. The role of the thymus and secondary lymphoid tissue injury, non‐haematopoietic cells, intestinal microflora, cytokines, chemokines, microRNAs, metabolites and kinases in aGVHD pathophysiology will be highlighted. Acute GVHD pathogenic mechanisms will be connected to novel therapeutic approaches under development for, and tested in, the clinic.     

Optimal management of chronic graft‐versus‐host disease in children

Chronic graft‐versus‐host disease (GVHD) is a major complication after allogeneic haematopoietic stem cell transplantation (HSCT). Not only is it the major cause of late mortality in HSCT patients, but it also accounts for significant morbidity. Much of the literature on chronic GVHD has focused on adults. Chronic GVHD is of major importance in children, especially since they have years to live following the complications of chronic GVHD and its therapy. The goal is to review incidence, manifestations, and therapies, especially when applicable to the paediatric population.     

Impairment of bone marrow endothelial progenitor cells in acute graft‐versus‐host disease patients after allotransplant

Graft‐versus‐host disease (GVHD) is a major complication after allogeneic haematopoietic stem cell transplantation (allo‐HSCT) that is frequently associated with bone marrow (BM) suppression, and clinical management is challenging. BM endothelial progenitor cells (EPCs) play crucial roles in the regulation of haematopoiesis and thrombopoiesis. However, little is known regarding the functional roles of BM EPCs in acute GVHD (aGVHD) patients. In the current prospective case‐control study, reduced and dysfunctional BM EPCs, characterized by decreased migration and angiogenesis capacities and increased levels of reactive oxygen species (ROS) and apoptosis, were found in aGVHD patients compared with those without aGVHD. Moreover, lower frequency and increased levels of ROS, apoptosis and DNA damage, but reduced colony‐forming unit‐plating efficiency were found in BM CD34⁺ cells of aGVHD patients compared with those without aGVHD. The severity of aGVHD and GVHD‐mediated cytopenia was associated with BM EPC impairment in aGVHD patients. In addition, the EPC impairment positively correlated with ROS level. Taken together, our results suggest that reduced and dysfunctional BM EPCs may be involved in the pathogenesis of aGVHD. Although these findings require validation, our data indicate that improvement of BM EPCs may represent a promising therapeutic approach for aGVHD patients.     

New ways to separate Graft‐versus‐Host Disease and Graft‐versus‐Tumour effects after allogeneic haematopoietic stem cell transplantation

A major challenge to transplant immunologists and physicians remains the separation of harmful graft‐versus‐host disease (GvHD) and beneficial graft‐versus‐tumour (GvT) effects after allogeneic haematopoietic stem cell transplantation. Recent advances in our understanding of the allogeneic immune response provide potential new opportunities to achieve this goal. Three potential new approaches that capitalize on this new knowledge are considered in depth; the manipulation of organ‐specific cytokines and other pro‐inflammatory signals, the selective manipulation of donor effector T cell migration, and the development of cell‐mediated immunosuppressive strategies using donor‐derived regulatory T cells. These new approaches could provide strategies for local control of allogeneic immune responses, a new paradigm to separate GvHD and GvT effects. Although these strategies are currently in their infancy and have challenges to successful translation to clinical practice, all have exciting potential for the future.     

Activating killer immunoglobulin‐like receptor incompatibilities enhance graft‐versus‐host disease and affect survival after allogeneic hematopoietic stem cell transplantation

Objectives: Killer immunoglobulin‐like receptors (KIRs) regulate function of natural killer (NK) cells and a subset of T cells. In this study, we prospectively evaluated the impact of donor and recipient activating KIR genes on outcome of allogeneic hematopoietic stem cell transplantation (alloHSCT) for patients with hematological malignancies. Methods: One‐hundred consecutive recipients of myeloablative transplantation and their donors were tested for KIR genotype as well as for immune reconstitution, including activating KIR expression on NK cells and T cells. Results: In a multivariate analysis, mismatches of particular activating KIRs such that the patient was negative and the donor was positive (P^?D⁺) resulted in increased risk of acute (KIR2DS1) and chronic (KIR2DS3) graft‐versus‐host disease (GVHD) as well as relapse (KIR2DS5). KIR2DS1 incompatibility in the same direction in the presence of HLA‐C‐group 2 ligand in recipient was associated with reduced overall (risk ratio, RR = 3.01; P = 0.01) and disease‐free survival (RR = 2.92, P = 0.03). Activating mismatches in P^?D⁺ direction resulted in decreased CD4⁺ : CD8⁺ T‐cell ratio up to 1 yr after alloHSCT, as a consequence of decreased CD3⁺CD4⁺ number within the first 100 d and increased CD3⁺CD8⁺ number in later time‐points. Among six evaluated patients, expression of activating KIRs on NK cells and T cells was particularly prominent for those developing intestinal GVHD. Conclusion: Our findings indicate that the presence of particular activating KIRs in donor with their absence in recipient enhances GVHD, which is not accompanied by graft‐versus‐leukemia effect. Evaluation of activating KIR genotype may allow optimization of both donor selection and transplantation procedure in order to avoid GVHD.     

Prevention of acute graft‐versus‐host disease by humanized anti‐CD26 monoclonal antibody

CD26 (DPP4) is a T cell costimulatory molecule as well as T cell activation marker, and CD26⁺ T cells are accumulated in inflamed tissues, such as rheumatoid synovitis and autoimmune thyroiditis. In the present study, we found accumulation of CD26⁺ T cells in graft‐versus‐host disease (GVHD) target organs. To expand our in vitro findings to an in vivo system, we examined CD26‐dependent organ injury in a xenogeneic GVHD (x‐GVHD) murine model. Following intraperitoneal injection of human peripheral blood mononuclear cells into non‐obese diabetic severe combined immunodeficiency/γ_c^?/? mice (hu‐PBL‐NOG mice), the mice exhibited the onset of GVHD symptoms associated with the presence of CD26^high human lymphocytes in the peripheral blood and GVHD target tissues. Administration of humanized anti‐human CD26 monoclonal antibody (mAb) decreased x‐GVHD severity and prolonged survival in hu‐PBL‐NOG mice without loss of engraftment of human T cells, while increasing doses of CTLA4‐ immunoglobulin fusion protein diminished engraftment of human lymphocytes. Importantly, anti‐CD26 mAb treatment preserved the graft‐versus‐leukaemia effects in studies using cotransplantation of P815 murine leukaemic cells. In addition, CD26⁺ lymphocytes infiltrated the GVHD patients' target tissues. Altogether, our data indicate a role for CD26 in the regulation of GVHD and point to CD26 as a novel target for therapeutic intervention in this disease.     

Oral chronic graft‐versus‐host disease in Australia: clinical features and challenges in management

Data from the Australasian Bone Marrow Transplant Recipient Registry show a steady increase in the number of allogeneic haemopoietic stem cell transplantations (HSCT) performed annually in Australia and New Zealand. In 2012, 629 allogeneic HSCT were performed. Allogeneic HSCT is associated with numerous potential complications, including chronic graft‐versus‐host disease (cGVHD). The oral cavity is one of the most frequent sites affected by cGvHD, often leading to significant disability and reduced quality of life. Management strategies are often complex, of variable efficacy and influenced by the availability of various therapeutic agents, access to compounding pharmacies and associated costs. This paper summarises the current status of allogeneic HSCT in Australia and New Zealand with a focus on oral cGvHD and the associated challenges in its management.     

The implications of myelodysplastic syndrome – associated chromosomal abnormalities in the development of graft‐versus‐host disease

There is a growing body of evidences that acquired chromosomal abnormalities in bone marrow (BM) cells are associated with clinical manifestations of myelodysplastic syndrome (MDS). However, to our knowledge, there are no reports that describe the association between chromosomal abnormalities in MDS and graft‐versus‐host disease (GVHD) after allogeneic stem cell transplantation (allo‐SCT). Here, we describe two MDS cases with trisomy 8 and der(1;7)(q10;p10), who developed severe GVHD after allo‐SCT. We analyzed cytokine production and cell survival of monocytes from these patients with MDS before allo‐SCT, in comparison with healthy controls or an MDS patient with a different chromosomal abnormality, who has not developed GVHD. The monocytes from MDS patients with trisomy 8 and der(1;7)(q10;p10) produced a larger amount of pro‐inflammatory cytokine, tumor necrosis factor‐α, and a smaller amount of anti‐inflammatory cytokine, interleukin‐10, on stimulation with Toll‐like receptor (TLR) ligands. In addition, the monocytes from MDS cases with GVHD showed a decrease in apoptotic cell death upon stimulation with TLR ligands. We also detected host‐derived pro‐inflammatory antigen‐presenting cells (APCs) in skin GVHD lesions after allo‐SCT. These data suggest that trisomy 8 and der(1;7)(q10;p10) may be associated with the development of severe GVHD, by prolonging survival of pro‐inflammatory host‐derived APCs in GVHD lesions.     

The addition of sirolimus to the graft‐versus‐host disease prophylaxis regimen in reduced intensity allogeneic stem cell transplantation for lymphoma: a multicentre randomized trial

Inhibition of the mechanistic target of rapamycin (mTOR) pathway has clinical activity in lymphoma. The mTOR inhibitor sirolimus has been used in the prevention and treatment of graft‐versus‐host disease (GVHD) after allogeneic haematopoietic stem cell transplantation (HSCT). A retrospective study suggested that patients with lymphoma undergoing reduced intensity conditioning (RIC) HSCT who received sirolimus as part of their GVHD prophylaxis regimen had a lower rate of relapse. We therefore performed a multicentre randomized trial comparing tacrolimus, sirolimus and methotrexate to standard regimens in adult patients undergoing RIC HSCT for lymphoma in order to assess the possible benefit of sirolimus on HSCT outcome. 139 patients were randomized. There was no difference overall in 2‐year overall survival, progression‐free survival, relapse, non‐relapse mortality or chronic GVHD. However, the sirolimus‐containing arm had a significantly lower incidence of grade II‐IV acute GVHD (9% vs. 25%, P = 0·015), which was more marked for unrelated donor grafts. In conclusion, the addition of sirolimus for GVHD prophylaxis in RIC HSCT is associated with no increased overall toxicity and a lower risk of acute GVHD, although it does not improve survival; this regimen is an acceptable option for GVHD prevention in RIC HSCT. This trial is registered at clinicaltrials.gov (NCT00928018).     

Invasive zygomycosis in patients with graft‐versus‐host disease after allogeneic stem cell transplantation

M. Leithauser, C. Kahl, C. Aepinus, F. Prall, M. Maruschke, H. Riemer, D. Wolff, K. Jost, I. Hilgendorf, M. Freund, C. Junghanss. Invasive zygomycosis in patients with graft‐versus‐host disease after allogeneic stem cell transplantation
Transpl Infect Dis 2010: 12: 251–257. All rights reserved Abstract: Invasive mold infections are a threat to immunosuppressed patients such as patients with graft‐versus‐host disease (GVHD) after allogeneic stem cell transplantation (SCT). Up to 10% of SCT recipients develop invasive aspergillosis (IA). Invasive zygomycosis (IZ) may occur during treatment against IA. Here we report 4 SCT patients with GVHD diagnosed with IZ. All patients had received myeloablative hematopoietic SCT and developed chronic GVHD requiring systemic immunosuppression. Underlying diseases were acute lymphocytic leukemia (2), osteomyelofibrosis, and multiple myeloma. All patients had developed pulmonary infiltration that led to initiation of antifungal therapy. Treatment for IA was voriconazole, caspofungin, or itraconazole. Organs involved with zygomycosis were lung, nasal sinus, skin, and kidney. Treatment with liposomal amphotericin and posaconazole was initiated in all patients, and 2 patients also had surgical debridement as well. Despite intensive treatment, no patient survived. IZ is becoming more common in patients with GVHD on successful treatment for IA. Even non‐specific symptoms are suspicious in this group of patients and need to be evaluated by vigorous diagnostics. Despite effective antifungals and surgical intervention, the prognosis is grim in patients with active GVHD, as immunoreconstitution is mandatory for successful management.     

Occurrence of graft‐versus‐host disease increases mortality after umbilical cord blood transplantation for acute myeloid leukaemia: a report from Eurocord and the ALWP of the EBMT

Background

The efficacy of umbilical cord blood transplantation (UCBT) as treatment for acute myeloid leukaemia (AML) relies on immune‐mediated graft‐versus‐leukaemia effects. Previous studies have suggested a strong association between graft‐versus‐host disease (GVHD) occurrence and graft‐versus‐leukaemia effects after allogeneic hematopoietic cell transplantation.

Methods

Here, we evaluated the kinetics of relapse rate in correlation with GVHD occurrence after UCBT. The kinetics of relapse rate over time in correlation to GVHD occurrence were assessed by calculating the relapse rate per patient‐year within sequential 90‐day intervals. The impact of GVHD on relapse and mortality was further studied in multivariate Cox models handling GVHD as a time‐dependent covariate.

Results

The study included data from 1068 patients given single (n  = 567) or double (n  = 501) UCBT. The proportion of patients with grade II, III and IV acute GVHD was 20%, 7% and 4%, respectively. At 2 years, the cumulative incidence of chronic GVHD was 42%, the cumulative incidence of relapse was 32%, and overall survival was 32% as well. Relapse rates declined gradually over time during the first 30 months after transplantation. There was a possible suggestion that grade II–IV acute (HR = 0.8, P  = 0.1) and chronic (HR = 0.65, P  = 0.1) GVHD decreased relapse risk. However, grade II–IV acute GVHD significantly increased early (the first 18 months after UCBT) mortality (HR = 1.3, P  = 0.02), whilst chronic GVHD increased each early (HR = 2.7, P  < 0.001) and late (HR = 4.9, P  < 0.001) mortality after UCBT.

Conclusions

The occurrence of grade II–IV acute or chronic GVHD each increases overall mortality after UCBT for AML mitigating the possible graft‐versus‐leukemia effect of GVHD.

     

Dermatopathic lymphadenopathy with Langerhans cell chimerism in graft‐versus‐host disease of the skin

Dermatopathic lymphadenopathy (DL) is well‐known in inflammatory skin disease; however, it has not been reported in graft‐versus‐host disease (GvHD) after allogeneic stem cell transplantation. Here, we report 2 cases of DL in patients with acute GvHD of the skin and demonstrate complete donor chimerism of Langerhans cells within the lymph nodes.     

Pre‐transplant comorbidity burden and post‐transplant chronic graft‐versus‐host disease

The Haematopoietic Cell Transplantation‐Comorbidity Index (HCT‐CI) was designed as a predictor of non‐relapse mortality after HCT. Chronic graft‐versus‐host disease (GVHD) contributes to mortality after HCT. Here, we investigated whether the HCT‐CI could predict development of chronic GVHD or post‐chronic GVHD mortality. We retrospectively analysed data from 2909 patients treated with allogeneic HCT for malignant and non‐malignant haematological conditions at four institutions. In Cox regression models adjusted for potential confounders, increasing HCT‐CI was not statistically significantly associated with the development of chronic GVHD [hazard ratio (HR) = 1·02, P = 0·34]. Yet, the index was associated with an increased risk of non‐relapse mortality (HR = 1·29, P < 0·0001) as well as overall mortality (HR = 1·25, P < 0·001) following the development of chronic GVHD. The association between HCT‐CI and post‐chronic GVHD mortality was similar regardless of donor type or stem cell source. HCT‐CI scores could be incorporated in the design of clinical trials for treatment of chronic GVHD.     

What is the outcome in patients with acute leukaemia who survive severe acute graft‐versus‐host disease?

Background

Acute graft‐versus‐host disease (aGVHD ) is a major complication of allogeneic haematopoietic stem cell transplantation (HSCT ). With new promising therapies, survival may improve for severe aGVHD .

Objectives

We wanted to analyze the long‐term outcome in patients who survive severe aGVHD .

Methods

This study was a landmark analysis of 23 567 patients with acute Leukaemia who survived for more than 6 months after HSCT , 2002–2014. Patients alive after severe aGVHD (n = 1738) were compared to controls.

Results

Patients with severe aGVHD had higher non‐relapse mortality (NRM ) and higher rate of extensive chronic GVHD (cGVHD ) than the controls (P < 10^?5). The probability of relapse was significantly lower in the severe aGVHD group, but Leukaemia‐free survival (LFS ) and overall survival were significantly lower than for the controls (P < 10^?5). Five‐year LFS in patients with severe aGVHD was 49%, as opposed to 61% in controls with no or mild GVHD and 59% in patients with moderate GVHD.

Conclusions

HSCT patients who survive severe aGVHD have higher risk of developing extensive cGVHD , a higher NRM , a lower relapse probability, and lower LFS than other HSCT patients. This study is a platform for outcome analysis in patients treated with novel therapies for acute GVHD.

     

Immunological effects in patients with steroid‐refractory graft‐versus‐host disease following treatment with basiliximab,a CD25 monoclonal antibody

Steroid‐refractory graft‐versus‐host disease (GvHD) is a complication following an allogeneic stem cell transplantation with limited therapeutic options. Studies have shown a response in up to 80% of patients with this condition after treatment with the CD25 monoclonal antibody, basiliximab. Despite the good responses to treatment, around 50% of the patients experience recurrence of their GvHD symptoms 4–6 wk following cessation of therapy. The in vivo changes in the following treatment with this antibody have not been elucidated so far. We treated 14 patients with severe steroid‐refractory GvHD with basiliximab weekly for 4 wk and monitored the changes in the T‐, B‐, NK‐ and dendritic cell subsets over this time period. The overall response to treatment was 92% (13/14) with 50% (7/14) achieving a complete response. Fifty four percentage (7/13) of the patients who responded showed recurrence of their GvHD symptoms. Contrary to expectations, our observations showed a significant depletion of the regulatory T‐cell subset following treatment. Our findings suggest that the undesirable depletion of the regulatory T cells along with the CD25⁺ acute inflammatory cells might be responsible for the high incidence of GvHD recurrence in this cohort of patients.     

Positive impact of chronic graft‐versus‐host disease on the outcome of patients with de novo myelodysplastic syndrome after allogeneic hematopoietic cell transplantation: a single‐center analysis of 115 patients

To evaluate the impact of graft‐versus‐host disease (GVHD) and prognostic factors for patients with myelodysplastic syndrome (MDS) after allogeneic hematopoietic cell transplantation (allo‐HCT), we retrospectively reviewed 115 patients with MDS or acute myeloid leukemia with multilineage dysplasia (AML‐MLD) after allo‐HCT at our center. Eighty one patients received reduced‐intensity conditioning (RIC) regimens, whereas 34 received myeloablative conditioning regimens. Although the RIC group was significantly older and included more patients with poor cytogenetic risk, no difference in 4‐yr overall survival (OS) was seen between the two groups. In a multivariate analysis, covariates associated with a worse OS were the French‐American‐British stage of refractory anemia excess blasts in transformation/AML‐MLD at peak, poor cytogenetic risk, bone marrow blasts of 20% or higher at HCT and the absence of chronic GVHD (cGVHD). By using semi‐landmark analyses, we found that the presence of cGVHD significantly improved OS in high‐risk patients or the RIC group. However, there was no difference in OS between those with and without cGVHD among low‐risk MDS patients. These findings suggest that the graft‐versus‐leukemia effect may be more beneficial in high‐risk patients who do not receive intensive preparative regimens.     

Absence of beta7 integrin results in less graft-versus-host disease because of decreased homing of alloreactive T cells to intestine

The alpha4beta7 integrin plays a central role in the homing of T cells to the gut. We hypothesized that absence of the beta7 subunit would result in a reduction of intestinal graft-versus-host disease (GVHD) and an improvement in overall GVHD morbidity and mortality in recipients of hematopoietic stem cell transplantation (HSCT). Analysis of alloreactive beta7-/- T cells showed intact activation, proliferation, cytokine production, and cytotoxicity. However, recipients of beta7-/- donor T cells in murine HSCT models experienced less GVHD morbidity and mortality than recipients of wild-type (WT) T cells, associated with a decrease in donor T-cell infiltration of the liver and intestine and with an overall significant decrease in hepatic and intestinal GVHD. In graft-versus-tumor (GVT) experiments, we demonstrated intact or even enhanced GVT activity of beta7-/- donor T cells. In conclusion, beta7-/- donor T cells caused less GVHD morbidity and mortality than WT donor T cells because of selectively decreased T-cell infiltration of the liver and intestines. Our data suggest that strategies to target the beta7 integrin have the clinical potential to alleviate or prevent GVHD while sparing or potentiating GVT activity.     

Acanthamoeba infection in a patient with chronic graft‐versus‐host disease occurring during treatment with voriconazole

Abstract: We report a case of disseminated infection with Acanthamoeba in a patient with graft‐versus‐host disease after hematopoietic stem cell transplant (HSCT) for acute lymphocytic leukemia. The infection involved the brain, skin, and lungs and occurred despite treatment with voriconazole for mold prophylaxis, and did not respond to treatment with multiple other agents reported to have activity against Acanthamoeba. To our knowledge, infection with Acanthamoeba has been reported in 4 other patients after HSCT or bone marrow transplant, and our case is the first to be diagnosed ante‐mortem.     

Nephrotic syndrome as a complication of chronic graft‐versus‐host disease after allogeneic haemopoietic stem cell transplantation

Nephrotic syndrome (NS) is a rare complication following allogeneic haemopoietic stem cell transplantation (allo‐HSCT), with limited current understanding of its pathogenesis. Here, we describe four cases of NS following allo‐HSCT diagnosed at our institutions to identify key clinical and pathological features. In addition, a PubMed search was performed to identify existing reports that were pooled together with our cases for analysis. NS occurred as a late complication following allo‐HSCT, with median onset 19.5 months after transplant (range: 3.9–84 months). The most common histopathology observed was membranous nephropathy; however, cases of minimal change disease have also been reported. There is a high incidence of prior extra‐renal graft‐versus‐host disease (GvHD), with all four of our cases and 82% of published cases having prior GvHD. Glucocorticosteroids are the most common treatment, with variable degrees of response. Responses to immunosuppression with calcineurin inhibitors and rituximab have been described in steroid‐refractory cases.     

Donor‐derived CD19‐targeted T cell infusion induces minimal residual disease‐negative remission in relapsed B‐cell acute lymphoblastic leukaemia with no response to donor lymphocyte infusions after haploidentical haematopoietic stem cell transplantation

Relapse is a common cause of failure in patients with B‐cell acute lymphoblastic leukaemia (B‐ALL) after haploidentical haematopoietic stem cell transplantation (haplo‐HSCT), and non‐responders to donor lymphoblastic infusion after HSCT have a very poor prognosis. Although donor‐derived CD19‐directed chimeric antigen receptor‐modified (CAR) T cells can potentially cure leukaemia, their effectiveness and safety have not been confirmed in relapsed B‐ALL cases after haplo‐HSCT. Between January 2015 and January 2017, two and four patients each received one and two infusions of CAR T cells from haplo‐HSCT donors. Five (83·33%) achieved minimal residual disease (MRD)‐negative remission; one patient was discharged automatically without evaluation after developing severe thrombotic microangiopathies. Four of five responsive patients relapsed after 2–7 months, and one died of sepsis following MRD‐negative remission after a second infusion. None of the other second infusion recipients achieved a second complete remission. Five patients (83·33%) experienced eight courses of grade 1–3 cytokine release syndrome; two were treated with tocilizumab. Two (33·3%) and one patient developed grade 2 and 3 acute graft‐versus‐host disease (aGVHD), respectively; the former was controlled with glucocorticoids. Donor‐derived CAR T‐cell infusion seems be effective and safe for relapsed B‐ALL after haplo‐HSCT, although larger clinical studies are needed.