Expansion and activation kinetics of immune cells during early phase of GVHD in mouse model based on chemotherapy conditioning

Profiles of interferon-gamma and interleukin-2 in patients after allogeneic hematopoietic stem cell transplantation

BACKGROUND

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) may be related to the occurrence of complications, including graft-versus-host disease (GvHD) and infections. The pathogenesis of acute GvHD is connected with T lymphocytes, which identify alloantigens on host's antigen-presenting cells, activate production of interferon-gamma (IFN-gamma) and interleukin-2 (IL-2), and act on the immune effector cells and damage tissues and organs.

AIM

The aim of the study was to investigate and distinguish serum concentration profiles of IFN-gamma and IL-2 within a 30-d period after allo-HSCT.

METHODS

We enrolled 62 patients, i.e., 30 (48%) male and 32 (52%) female subjects [median age 49.5 (19-68) years], after allo-HSCT from siblings (n = 12) or unrelated donors (n = 50) due to acute myeloid leukemia with myeloablative conditioning (n = 26; 42%) and with non-myeloablative conditioning (n = 36; 58%). All patients were given standard immunosuppressive therapy with cyclosporin-A and methotrexate and pre-transplant antithymocyte globulin in the unrelated setting. Blood samples were collected pre-transplant before and after (on day -1) the conditioning therapy and on days +2,+4, +6, +10, +20, and +30 after allo-HSCT. Serum levels of IL-2 and IFN-gamma were determined using ELISA.

RESULTS

Patients were divided into four groups depending on the presence of acute GvHD and clinical manifestations of infection. Group I included patients with neither acute GvHD nor infections [n = 15 (24%)], group II consisted of patients with infections without acute GvHD [n = 17 (27%)], group III was comprised of patients with acute GvHD without infections [n = 9 (15%)], and group IV included patients with both acute GvHD and infections [n = 21 (34%)]. IFN-gamma concentrations were higher in Group II than in other groups on days +20 (P = 0.014) and +30 (P = 0.008). Post-hoc tests showed lower concentrations of IFN-gamma on day +30 in groups I (P = 0.039) and IV (P = 0.017) compared to group II. The levels of IL-2 were mostly undetectable.

CONCLUSION

Serum levels of IFN-gamma following allo-HSCT progressively escalate. High serum levels of IFN-gamma are related to infectious complications rather than acute GvHD. Serum concentrations of IL-2 in most patients are undetectable.

Early Endothelial Activation in a Mouse Model of Graft vs Host Disease Following Chemotherapy

Allogenic hematopoietic stem cell transplant (allo-HSCT) can lead to sinusoidal obstruction syndrome (SOS) and graft-versus-host disease (GvHD) in some individuals. GvHD is characterised by an immune triggered response that arises due to donor T cells recognizing the recipient tissue as “foreign”. SOS results in impaired liver function due to microvascular thrombosis and consequent obstruction of liver sinusoids. Endothelial damage occurs following chemotherapy and allo-HSCT and is strongly associated with GvHD onset as well as hepatic SOS. Animal models of GvHD are rarely clinically relevant, and endothelial dysfunction remains uncharacterised. Here we established and characterised a clinically relevant model of GvHD wherein Balb/C mice were subjected to myeloablative chemotherapy followed by transplantation of bone marrow (BM) cells± splenic T-cells from C57Bl6 mice, resulting in a mismatch of major histocompatibility complexes (MHC). Onset of disease indicated by weight loss and apoptosis in the liver and intestine was discovered at day 6 post-transplant in mice receiving BM+T-cells, with established GvHD detectable by histology of the liver within 3 weeks. Together with significant increases in pro-inflammatory cytokine gene expression in the liver and intestine, histopathological signs of GvHD and a significant increase in CD4+ and CD8+ effector and memory T-cells were seen. Endothelial activation including upregulation of vascular cell adhesion molecule (VCAM)- 1 and downregulation of endothelial nitric oxide synthase (eNOS) as well as thrombosis in the liver indicated concomitant hepatic SOS. Our findings confirm that endothelial activation is an early sign of acute GvHD and SOS in a clinically relevant mouse model of GvHD based on myeloablative chemotherapy. Preventing endothelial activation may be a viable therapeutic strategy to prevent GvHD.

Proliferation kinetics of immune cells during early phase of bone marrow transplantation in mouse model based on chemotherapy conditioning

OBJECTIVES

To establish mouse bone marrow transplantation by pretreatment with chemotherapy, and to explore the dynamic changes of immune cells in the early stage of allogeneic transplantation in the spleen of mice.

METHODS

Mice were divided into 4 groups (80 mg/kg group, 100 mg/kg group, 120 mg/kg group, and 150 mg/kg group) according to the difference in dose of busulfan. The mice were treated with busulfan and cyclophosphamide combined chemotherapy, and the appropriate dosage was determined by evaluating the myeloablative effect and drug toxicity. According to the type of the genetic transplantation, the mice were also divided into 4 groups: An allogeneic transplantation group, a homogenic transplantation group, a chemotherapy alone group, and a normal control group. The mice were pretreated with busulfan and cyclophosphamide before bone marrow transplantation. In the allogeneic transplantation group, the suspension of splenocytes was prepared at the first day, the 3rd day, the 5th day, and the 8th day after transplantation for flow cytometry detection, and the dynamic changes of splenic immune cells were analyzed. The homogeneic transplantation group served as the concurrent control, the normal control group served as the control of basic value of spleen immune cells, and the chemotherapy alone group was used to evaluate the myeloablative effect.

RESULTS

1) The optimal dose of busulfan was 100 mg/kg. The combination of busulfan and cyclophosphamide can restore the hematopoiesis of transplanted mice, and the toxicity associated with pretreatment is small. 2) In the allogeneic transplantation group: The hematopoietic reconstitution and high donor chimerism rate were achieved after transplantation. In the early phase of bone marrow transplantation, the T lymphocytes were the main cell group, while the recovery of B lymphocytes was relatively delayed. The dendritic cells and natural killer cells from donors were the earliest cells to recover and achieve high chimerism rate compared with T cells and B cells. Most T cells were in the initial T cell state within 5 days after allogeneic transplantation. However, in the 5th day after transplantation, these cells were mainly in the effective memory phenotype. The reconstruction of donor-derived naive T cells was slow, but the reconstruction of donor-derived effective memory T cells and regulatory T cells was relatively fast. 3) In the homogeneic transplantation group: The mice could recover hematopoiesis and the recovery of B lymphocytes was delayed. 4) In the chemotherapy alone group: All mice died in 12-15 days after chemotherapy, and the peripheral blood routine showed pancytopenia before death.

CONCLUSIONS

Pretreatment with chemotherapy can successfully establish the mouse model of bone marrow transplantation. There are difference in the proportion of T cells, B cells, natural killer cells, dendritic cells, effector memory T cells, initial T cells, and regulatory T cells after transplantation, and the relationship between donor and recipient is also changed.

Dipeptidyl Peptidase 4 Inhibition for Prophylaxis of Acute Graft-versus-Host Disease

BACKGROUND

Dipeptidyl peptidase 4 (DPP-4; also known as CD26), a transmembrane receptor expressed on T cells, has a costimulatory function in activating T cells. In a mouse model, down-regulation of CD26 prevented graft-versus-host disease (GVHD) but preserved graft-versus-tumor effects. Whether inhibition of DPP-4 with sitagliptin may prevent acute GVHD after allogeneic stem-cell transplantation is not known.

METHODS

We conducted a two-stage, phase 2 clinical trial to test whether sitagliptin plus tacrolimus and sirolimus would reduce the incidence of grade II to IV acute GVHD from 30% to no more than 15% by day 100. Patients received myeloablative conditioning followed by mobilized peripheral-blood stem-cell transplants. Sitagliptin was given orally at a dose of 600 mg every 12 hours starting the day before transplantation until day 14 after transplantation.

RESULTS

A total of 36 patients who could be evaluated, with a median age of 46 years (range, 20 to 59), received transplants from matched related or unrelated donors. Acute GVHD occurred in 2 of 36 patients by day 100; the incidence of grade II to IV GVHD was 5% (95% confidence interval [CI], 1 to 16), and the incidence of grade III or IV GVHD was 3% (95% CI, 0 to 12). Nonrelapse mortality was zero at 1 year. The 1-year cumulative incidences of relapse and chronic GVHD were 26% (95% CI, 13 to 41) and 37% (95% CI, 22 to 53), respectively. GVHD-free, relapse-free survival was 46% (95% CI, 29 to 62) at 1 year. Toxic effects were similar to those seen in patients undergoing allogeneic stem-cell transplantation.

CONCLUSIONS

In this nonrandomized trial, sitagliptin in combination with tacrolimus and sirolimus resulted in a low incidence of grade II to IV acute GVHD by day 100 after myeloablative allogeneic hematopoietic stem-cell transplantation. (Funded by the National Heart, Lung, and Blood Institute; ClinicalTrials.gov number, NCT02683525.).

Photochemotherapy and Graft-versus-Leukemia Reaction in Acute Leukemia: Tumor Immunity and Survival Are Dependent on Timing of Photochemotherapy of the Skin

BACKGROUND

Cure of acute leukemia after transplantation is mediated by the grafted cells. We investigated the graft-versus-leukemia effect (GVL) in patients with cutaneous acute graft-versus-host disease (GVHD) treated with photochemotherapy (psoralen and ultraviolet light type A).

METHOD

Forty-seven patients with acute leukemia were followed 5,000 days after transplantation to assess survival and GVL by multivariate analysis. The primary predictor was time to treatment of cutaneous acute GVHD by photochemotherapy separated into treatment start during the first week of acute GVHD versus after the first week of acute GVHD.

RESULTS

Photochemotherapy started after the first week of acute GVHD predicted GVL with a hazard ratio (HR) of 3.94 (95% confidence interval, CI, 1.67-9.33, p = 0.0018) and survival with preserved GVL with an HR of 2.63 (95% CI 1.30-5.32, p = 0.007). The effects on GVL and survival with preserved GVL were present regardless of whether the patients were transplanted in remission or relapse (p < 0.05). Chronic GVHD came earlier in the group that started photochemotherapy after 1 week of acute GHVD, but chronic GVHD did not increase the GVL.

CONCLUSION

The timing of photochemotherapy after cutaneous acute GVHD may direct the GVL and predict long-term leukemia-free survival.

A preclinical acute GVHD mouse model based on chemotherapy conditioning and MHC-matched transplantation

Animal disease models have been criticized for lack of resemblance to human illnesses, hampering transfer of knowledge from preclinical research to clinical medicine. In the field of allogeneic hematopoietic stem cell transplantation (allo-HSCT), it is standard practice to study GVHD in lethal TBI-based murine models. Frequently, MHC-mismatched donors are used in GVHD models. In contrast, in clinical allo-HSCT conditioning with chemotherapy (+/-TBI) is common and donors are often MHC-matched. Aiming at a more clinically oriented situation, we established and characterized a murine MHC-matched, minor histocompatibility antigen mismatched GVHD model (LP/J [H2k(b)]-->C57BL/6 [H2k(b)]) using busulfan and cyclophosphamide conditioning. We found typical clinical and histological features of acute GVHD. T-cell infiltration, GVHD-specific damage and systemic inflammation were similar to observations made in patients after allo-HSCT. In survivors of acute GVHD, we found expansion of CD4+ T cells and the development of scleroderma-like chronic GVHD. The use of chemotherapy-based, minor histocompatibility antigen (miHA)-mismatched GVHD animal models may be a good option when studying clinically relevant questions in the field of allo-HSCT.

Dendritic cell chimerism in oral mucosa of transplanted patients affected by graft-versus-host disease

OBJECTIVE

Graft-versus-host disease (GVHD) is one of the main complications after haematopoietic stem cell transplantation. Clinical features of GVHD include either an acute (aGVHD) or a chronic (cGVHD) condition that affects locations such as the oral mucosa. While the involvement of the host's dendritic cells (DCs) has been demonstrated in aGVHD, the origin (donor/host) and mechanisms underlying oral cGVHD have not been completely elucidated. In this study, we intend to determine the origin of DCs present in mucosal tissue biopsies from the oral cavity of transplanted patients affected by cGVHD.

METHODS

We purified DCs, from oral biopsies of three patients with cGVHD, through immunobeads and subsequently performed DNA extraction. The origin of the obtained DCs was determined by PCR amplification of 13 informative short tandem repeat (STR) alleles. We also characterised the DCs phenotype and the inflammatory infiltrate from biopsies of two patients by immunohistochemistry.

RESULTS

Clinical and histological features of the biopsies were concordant with oral cGVHD. We identified CD11c-, CD207- and CD1a-positive cells in the epithelium and beneath the basal layer. Purification of DCs from the mucosa of patients affected by post-transplantation cGVHD was >95%. PCR-STR data analysis of DCs DNA showed that 100% of analysed cells were of donor origin in all of the evaluated patients.

CONCLUSION

Our results demonstrate that resident DCs isolated from the oral tissue of allotransplanted patients affected by cGVHD are originated from the donor. Further research will clarify the role of DCs in the development and/or severity of oral cGVHD.

Cytostatic conditioning in experimental allogeneic bone marrow transplantation: Busulfan causes less early gastrointestinal toxicity but Treosulfan results in improved immune reconstitution

BACKGROUND

Acute graft versus host disease (aGVHD) after allogeneic bone marrow transplantation (allo-BMT) is associated with significant morbidity and mortality. We evaluated the impact of the conditioning regimen on aGVHD comparing Treosulfan (Treo) and Busulfan (Bu) with total body irradiation (TBI).

METHODS

Using a haploidentical murine model, B6D2F1 mice conditioned with Bu (100 mg/kg)/Fludarabine (Flu, 500 mg/kg) or Treo (6000 mg/kg)/Flu (500 mg/kg) or TBI with 14 Gy received bone marrow cells and splenocytes (20 × 10(6)) from either syngeneic (B6D2F1) or allogeneic (C57BL/6N) donors in order to analyze aGVHD outcome.

RESULTS

Conditioning with Bu/Flu or Treo/Flu resulted in significantly reduced aGVHD severity and improved survival (p < 0.05) after allo-BMT compared to TBI. On day 5 after allo-BMT, the organ damages of Bu/Flu conditioned animals were significantly reduced in association with diminished expression of tumor necrosis factor in serum compared to Treo/Flu. Interestingly, the early toxicity of Treo/Flu did not result in significantly higher aGVHD severity; furthermore, a significantly improved immune reconstitution of B220-positive B cells was observed at day 42 after Treo/Flu conditioning compared to Bu/Flu.

CONCLUSION

Conditioning with Treo/Flu or Bu/Flu results in decreased aGVHD severity compared to TBI. Moreover, Treo/Flu was associated with improved immune reconstitution despite the early toxicity.

Clinical significance of anti-endothelial cell antibody in allogeneic hematopoietic stem cell transplantation recipients with graft-versus-host disease

Anti-endothelial cell antibody (AECA) is well known to reflect endothelial injury. Graft-versus-host disease (GVHD), a major complication of allogeneic hematopoietic stem cell transplantation (allo-HSCT), is also closely associated with endothelial injury. We hypothesized that AECA may be associated with GVHD. To investigate the clinical significance of AECA in allo-HSCT recipients with GVHD, we detected AECA by cyto-enzyme-linked immunosorbent assay (cyto-ELISA) in allo-HSCT recipients with acute and/or chronic GVHD (aGVHD and cGVHD). Incidences of anti-HMEC-1 AECA (anti-HMEC) and anti-EA.hy926 AECA (anti-EAHY) were significantly higher in patients with grade II-IV than grade 0-I aGVHD (P = 0.049, P = 0.011, respectively). There was no difference in the incidence of AECA between patients with and without cGVHD. Patients with anti-EAHY positive in the early stage post-transplant demonstrated a higher incidence of cGVHD (P = 0.044). In patients with grade 0-I aGVHD, AECA-positive patients had higher overall survival and disease-free survival (P < 0.05), and tended to have lower incidences of relapse and transplant-related mortality. Our data suggest that AECA plays an important role in the pathogenesis of GVHD.

The role of programmed cell death ligand-1 (PD-L1/CD274) in the development of graft versus host disease

Programmed cell death ligand-1 (PD-L1/CD274) is an immunomodulatory molecule involved in cancer and complications of bone marrow transplantation, such as graft rejection and graft-versus-host disease. The present study was designed to assess the dynamic expression of this molecule after hematopoietic stem cell transplantation in relation to acute graft-versus-host disease. Female BALB/c mice were conditioned with busulfan and cyclophosphamide and transplanted with either syngeneic or allogeneic (male C57BL/6 mice) bone marrow and splenic cells. The expression of PD-L1 was evaluated at different time points employing qPCR, western blot and immunohistochemistry. Allogeneic- but not syngeneic-transplanted animals exhibited a marked up-regulation of PD-L1 expression in the muscle and kidney, but not the liver, at days 5 and 7 post transplantation. In mice transplanted with allogeneic bone marrow cells, the enhanced expression of PD-L1 was associated with high serum levels of IFNγ and TNFα at corresponding intervals. Our findings demonstrate that PD-L1 is differently induced and expressed after allogeneic transplantation than it is after syngeneic transplantation, and that it is in favor of target rather than non-target organs at the early stages of acute graft-versus-host disease. This is the first study to correlate the dynamics of PD-L1 at the gene-, protein- and activity levels with the early development of acute graft-versus-host disease. Our results suggest that the higher expression of PD-L1 in the muscle and kidney (non-target tissues) plays a protective role in skeletal muscle during acute graft-versus-host disease.

Macrophage inflammatory protein-2 (MIP-2)/CXCR2 blockade attenuates acute graft-versus-host disease while preserving graft-versus-leukemia activity

Allogenic bone marrow transplantation (BMT), an important treatment for hematological malignancies, is often complicated by graft-versus-host disease (GVHD). Suppression of GVHD is associated with the unwanted diminishment of the graft-versus-leukemia (GVL) response. The aim of this study was to maintain the benefits of GVL during GVHD suppression through isolated blockade of T-cell migration factors. To this end, we developed a murine model of B-cell leukemia, which was treated with BMT to induce GVHD. Within this model, functional blockade of MIP-2/CXCR2 was analyzed by observing proteomic, histologic and clinical variables of GVHD manifestation. Luminex assay of collected tissue identified several cytokines [granulocyte colony-stimulating factor (G-CSF), keratinocyte-derived chemokine (KC), macrophage inflammatory protein-2 (MIP-2), and interleukin-23 (IL-23)] that were upregulated during GHVD, but reduced by neutralizing the MIP-2/CXCR2 axis. In addition, donor T-cell blockade of CXCR2 combined with recipient administration of anti-MIP-2 caused a significant decrease in GVHD while preserving the GVL response. We propose that blocking the MIP-2/CXCR2 axis represents a novel strategy to separate the toxicity of GVHD from the beneficial effects of GVL after allogenic BMT.

Busulphan-cyclophosphamide cause endothelial injury, remodeling of resistance arteries and enhanced expression of endothelial nitric oxide synthase

Stem cell transplantation (SCT) is a curative treatment for malignant and non malignant diseases. However, transplantation-related complications including cardiovascular disease deteriorate the clinical outcome and quality of life. We have investigated the acute effects of conditioning regimen on the pharmacology, physiology and structure of large elastic arteries and small resistance-sized arteries in a SCT mouse model. Mesenteric resistance arteries and aorta were dissected from Balb/c mice conditioned with busulphan (Bu) and cyclophosphamide (Cy). In vitro isometric force development and pharmacology, in combination with RT-PCR, Western blotting and electron microscopy were used to study vascular properties. Compared with controls, mesenteric resistance arteries from the Bu-Cy group had larger internal circumference, showed enhanced endothelium mediated relaxation and increased expression of endothelial nitric oxide synthase (eNOS). Bu-Cy treated animals had lower mean blood pressure and signs of endothelial injury. Aortas of treated animals had a higher reactivity to noradrenaline. We conclude that short-term consequences of Bu-Cy treatment divergently affect large and small arteries of the cardiovascular system. The increased noradrenaline reactivity of large elastic arteries was not associated with increased blood pressure at rest. Instead, Bu-Cy treatment lowered blood pressure via augmented microvascular endothelial dependent relaxation, increased expression of vascular eNOS and remodeling toward a larger lumen. The changes in the properties of resistance arteries can be associated with direct effects of the compounds on vascular wall or possibly indirectly induced via altered translational activity associated with the reduced hematocrit and shear stress. This study contributes to understanding the mechanisms that underlie the early effects of conditioning regimen on resistance arteries and may help in designing further investigations to understand the late effects on vascular system.

Dynamics of early histopathological changes in GVHD after busulphan/cyclophosphamide conditioning regimen

Hematopoietic stem cell transplantation (HSCT) is a curative treatment for otherwise incurable diseases. Conditioning regimen is an important part of HSCT and consists of chemotherapy with or without irradiation. Conditioning exerts myelosuppressive, immunosuppressive and antitumor effects, but also contributes to HSCT-related complications including graft-versus-host disease (GVHD). Since almost 50% of the transplanted patients are conditioned with cytostatics without irradiation, we developed and characterized a GVHD mouse model following conditioning with busulphan and cyclophosphamide. Recipient Balb/c female mice were treated with busulphan (20 mg/kg/day for 4 days) and cyclophosphamide (100 mg/kg/day for two days). After one day of rest, recipient mice were transplanted with 2×10(7) bone marrow and 3×10(7) spleen cells from male C57BL/6 (allogeneic group) or female Balb/c (syngeneic/control group) mice. The allogeneic, but not syngeneic transplanted mice developed GVHD. Histopathology of the major internal organs (liver, pancreas, spleen, lungs, heart and kidney) was examined before conditioning start, after conditioning's end and 5, 7 and 21 days after transplantation using hematoxylin-eosin staining. Decreased spleen cellularity and diminished glycogen content in the liver were observed after conditioning regimen. Histopathological changes such as vasculitis, inflammation and apoptotic cell forms in liver, spleen, pancreas, lungs and heart were observed in allogeneic transplanted mice, however, only hypocellular spleen and extramedullar hematopoiesis were detected in syngeneic transplanted animals. No morphological changes were observed in kidney in either HSCT setting. This is the first study describing early histopathological changes after conditioning regimen with busulphan/cyclophosphamide and dynamics of GVHD development in several major internal organs.