Kinetic analysis of cytokine gene expression in patients with GVHD after donor lymphocyte infusion

Interferon regulatory factor 4 plays a pivotal role in the development of aGVHD-associated colitis

Interferon regulatory factor 4 (IRF4) is a master transcription factor that regulates T helper cell (Th) differentiation. It interacts with the Basic leucine zipper transcription factor, ATF-like (BATF), depletion of which in CD4+ T cells abrogates acute graft-versus-host disease (aGVHD)-induced colitis. Here, we investigated the immune-regulatory role of Irf4 in a mouse model of MHC-mismatched bone marrow transplantation. We found that recipients of allogenic Irf4-/- CD4+ T cells developed less GVHD-related symptoms. Transcriptome analysis of re-isolated donor Irf4-/- CD4+ T helper (Th) cells, revealed gene expression profiles consistent with loss of effector T helper cell signatures and enrichment of a regulatory T cell (Treg) gene expression signature. In line with these findings, we observed a high expression of the transcription factor BTB and CNC homolog 2; (BACH2) in Irf4-/- T cells, which is associated with the formation of Treg cells and suppression of Th subset differentiation. We also found an association between BACH2 expression and Treg differentiation in patients with intestinal GVHD. Finally, our results indicate that IRF4 and BACH2 act as counterparts in Th cell polarization and immune homeostasis during GVHD. In conclusion, targeting the BACH2/IRF4-axis could help to develop novel therapeutic approaches against GVHD.

IL-10 mRNA Engineered MSCs Demonstrate Enhanced Anti-Inflammation in an Acute GvHD Model

Mesenchymal stem cells (MSCs) are used in various studies to induce immunomodulatory effects in clinical conditions associated with immune dysregulation such as graft versus host disease (GvHD). However, most of these clinical trials failed to go beyond early phase 2 studies because of limited efficacy. Various methods have been assessed to increase the potency of MSCs. IL-10 is an anti-inflammatory cytokine that is known to modulate immune responses in GvHD. In this study, we evaluated the feasibility of transfecting IL-10 mRNA to enhance MSC therapeutic potential. IL-10 mRNA engineered MSCs (eMSCs-IL10) maintained high levels of IL-10 expression even after freezing and thawing. IL-10 mRNA transfection did not appear to alter MSC intrinsic characteristics. eMSCs-IL10 significantly suppressed T cell proliferation relative to naïve MSCs in vitro. In a mouse model for GvHD, eMSCs-IL10 induced a decrease in plasma level of potent pro-inflammatory cytokines and inhibited CD4+ and CD8+ T cell proliferation in the spleen. In summary, our studies demonstrate the feasibility of potentiating MSCs to enhance their immunomodulatory effects by IL-10 mRNA transfection. The use of non-viral transfection may generate a safe and potent MSC product for treatment of clinical conditions associated with immune dysregulation such as GvHD.

The feasibility and efficacy of subcutaneous plerixafor for mobilization of peripheral blood stem cells in allogeneic HLA-identical sibling donors: results of the HOVON-107 study

Background

Plerixafor (PFX) mobilizes CD34+ cells into circulation by disrupting the CXCR4 binding of the hematopoietic stem cell in its bone marrow niche.

Study design and Methods

in the prospective HOVON‐107 study (www.hovon.nl) 23 allogeneic HLA–identical sibling donors received one or two subcutaneous (sc) injections of plerixafor 0.320 mg/kg.The primary endpoint, was defined as feasibility to mobilize a minimum of 2.0 x10⁶ CD34+ cells/kg recipient weight obtained by leukopheresis in at least 90% of the donors.

Results

median 3.3 x 10⁶ CD34⁺ cells/kg (1.9‐6.5) were collected after 1 (n=12) or 2 (n=10) sc injections of PFX. Side effects occurred in 15/23 (65%) donors: most were grade 1‐2; in 5 donors grade 3 and all resolved. All grafts were directly transplanted. Compared to 10 grafts obtained with G‐CSF the number of CD34+ cells was 2.4 fold lower but the percentage of phenotypically most immature CD34+ subset was higher (31% vs 15%). The total number of CD3+ cells in the graft seemed higher after PFX‐mobilization, but CD4/CD 8 ratios, and frequencies of Th2, Th17 and regulatory T‐cells or NK cells were comparable. All patients engrafted and no increase in incidence or severity of acute or chronic graft versus host disease was observed.

Conclusion

stem cell mobilization with sc PFX 0.320 mg/kg in allogeneic sibling donors is feasible with limited toxicity for donors. 14 allogeneic donors were mobilized with PFX 0.320 mg intravenously according to the same protocol. Due to the limited numbers, these results are in the supplementary section.

Genetic Association of Hematopoietic Stem Cell Transplantation Outcome beyond Histocompatibility Genes

The outcome of hematopoietic stem cell transplantation (HSCT) is controlled by genetic factors among which the leukocyte antigen human leukocyte antigen (HLA) matching is most important. In addition, minor histocompatibility antigens and non-HLA gene polymorphisms in genes controlling immune responses are known to contribute to the risks associated with HSCT. Besides single-nucleotide polymorphisms (SNPs) in protein coding genes, SNPs in regulatory elements such as microRNAs (miRNAs) contribute to these genetic risks. However, genetic risks require for their realization the expression of the respective gene or miRNA. Thus, gene and miRNA expression studies may help to identify genes and SNPs that indeed affect the outcome of HSCT. In this review, we summarize gene expression profiling studies that were performed in recent years in both patients and animal models to identify genes regulated during HSCT. We discuss SNP–mRNA–miRNA regulatory networks and their contribution to the risks associated with HSCT in specific examples, including forkheadbox protein 3 and regulatory T cells, the role of the miR-155 and miR-146a regulatory network for graft-versus-host disease, and the function of MICA and its receptor NKG2D for the outcome of HSCT. These examples demonstrate how SNPs affect expression or function of proteins that modulate the alloimmune response and influence the outcome of HSCT. Specific miRNAs targeting these genes and directly affecting expression of mRNAs are identified. It might be valuable in the future to determine SNPs and to analyze miRNA and mRNA expression in parallel in cohorts of HSCT patients to further elucidate genetic risks of HSCT.

Role of CD8 Regulatory T Cells versus Tc1 and Tc17 Cells in the Development of Human Graft-versus-Host Disease

CD8⁺ T cells that secrete proinflammatory cytokines play a central role in exacerbation of inflammation; however, a new subpopulation of CD8 regulatory T cells has recently been characterized. This study analyzes the prominent role of these different subpopulations in the development of graft-versus-host disease (GVHD). Samples from 8 healthy donors mobilized with Filgrastim® (G-CSF) and 18 patients who underwent allogeneic hematopoietic stem cell transplantation (HSCT) were evaluated by flow cytometry. Mobilization induced an increase in Tc1 (p < 0.01), Th1 (p < 0.001), Tc17 (p < 0.05), and CD8⁺IL-10⁺ cells (p < 0.05), showing that G-CSF induces both pro- and anti-inflammatory profiles. Donor-patient correlation revealed a trend (p = 0.06) toward the development of GVHD in patients who receive a high percentage of Tc1 cells. Patients with acute GVHD (aGVHD), either active or controlled, and patients without GVHD were evaluated; patients with active aGVHD had a higher percentage of Tc1 (p < 0.01) and Tc17 (p < 0.05) cells, as opposed to patients without GVHD in whom a higher percentage of CD8 Treg cells (p < 0.01) was found. These findings indicate that the increase in Tc1 and Tc17 cells is associated with GVHD development, while regulatory CD8 T cells might have a protective role in this disease. These tests can be used to monitor and control GVHD.

Alloreactive effector T cells require the local formation of a proinflammatory environment to allow crosstalk and high avidity interaction with nonhematopoietic tissues to induce GVHD reactivity

Based on clinical observations that donor T cells specific for minor histocompatibility antigens (MiHA) ubiquitously expressed on both hematopoietic and nonhematopoietic cells were detected in patients showing evident graft-versus-leukemia/lymphoma (GVL) reactivity with no or limited coinciding graft-versus-host disease (GVHD), we hypothesized that nonhematopoietic tissues may be relatively unsusceptible to the cytotoxic effect of MiHA-specific T cells under normal, noninflammatory conditions. To test this hypothesis, we investigated the reactivity of alloreactive T cells specific for ubiquitously expressed MiHA against skin-derived primary human fibroblasts. We demonstrated that this reactivity was not merely determined by their antigen-specificity, but was highly dependent on adhesion molecule expression. ICAM-1 expression on the fibroblasts upregulated under proinflammatory conditions and induced during cross-talk with the T cells was demonstrated to be a crucial factor facilitating formation of high avidity interactions with the T cells and subsequent efficient target cell destruction. Furthermore, we provide supporting evidence for the role of ICAM-1 in vivo by demonstrating that ICAM-1 expression on nonhematopoietic target cells was dependent on the presence of infiltrating activated T cells, as was illustrated by restricted ICAM-1 expression at the sites of T cell infiltration in skin biopsies of patients with acute GVHD (aGVHD), by the absence of ICAM-1 expression in the same biopsies in areas without T cell infiltration and by the absence of ICAM-1 expression in biopsies of patients without GVHD independent of the presence of infiltrating nonactivated T cells. In conclusion, under noninflammatory conditions, nonhematopoietic tissues are unsusceptible to the GVHD reactivity of alloreactive T cells due to their inability to establish high avidity interactions.

Single nucleotide polymorphisms and outcome risk in unrelated mismatched hematopoietic stem cell transplantation: an exploration study

Genetic risk factors contribute to adverse outcome of hematopoietic stem cell transplantation (HSCT). Mismatching of the HLA complex most strongly determines outcomes, whereas non-HLA genetic polymorphisms are also having an impact. Although the majority of HSCTs are mismatched, only few studies have investigated the effects of non-HLA polymorphisms in the unrelated HSCT and HLA-mismatched setting. To understand these effects, we genotyped 41 previously studied single nucleotide polymorphisms (SNPs) in 2 independent, large cohorts of HSCT donor-recipient pairs (n = 460 and 462 pairs) from a homogeneous genetic background. The study population was chosen to pragmatically represent a large clinically homogeneous group (acute leukemia), allowing all degrees of HLA matching. The TNF-1031 donor-recipient genotype mismatch association with acute GVHD grade 4 was the only consistent association identified. Analysis of a subgroup of higher HLA matching showed consistent associations of the recipient IL2-330 GT genotype with risk of chronic GVHD, and the donor CTLA4-CT60 GG genotype with protection from acute GVHD. These associations are strong candidates for prediction of risk in a clinical setting. This study shows that non-HLA gene polymorphisms are of relevance for predicting HSCT outcome, even for HLA mismatched transplants.

The interferon-dependent orchestration of innate and adaptive immunity after transplantation

The therapeutic GVL effect after allogeneic stem cell transplantation is limited by the development of GVHD. The ultimate aim of current research is to separate the 2 processes in a meaningful fashion. The IFNs are a pleiotropic group of cytokines that were originally recognized because of their ability to interfere with viral replication. However, it is now established that these cytokines play an important role in orchestrating both innate and adaptive immunity. Multiple studies have investigated the effects of both types I and II IFN on GVHD and GVL in preclinical transplant models. The results indicate variable effects that are dependent on the period of activity within the developing immune response, the presence and type of pretransplant conditioning and the differential mechanisms, and IFN sensitivity of immune pathology within individual target organs during GVHD. This Perspective discusses the current literature on the IFNs and their potential modulation within clinical transplantation, focusing particularly on enhancing the therapeutic GVL effects.

Idiopathic pneumonia syndrome in mice after allogeneic bone marrow transplantation: association between idiopathic pneumonia syndrome and acute graft-versus-host disease

OBJECTIVE

To explore the association between idiopathic pneumonia syndrome (IPS) and acute graft-versus-host disease (aGVHD) in allogeneic hematopoietic stem cell transplantation.

METHODS

Established acute GVHD model of C57BL/6-->BALB/c mice. Chest computed tomography (CT) scans were dynamically performed in recipient mice after transplant. Lung histopathology and cytokine levels (including TNF-alpha and IFN-gamma) were examined in three experimental groups: mice receiving simple irradiation, syngeneic transplants, and allogeneic transplants.

RESULTS

All allogeneic transplant mice developed aGVHD. On CT, most aGVHD mice had bilateral diffuse lung infiltrates, while syngeneic transplant mice had normal lungs. On histopathology, aGVHD mice had acute pneumonitis. On immunohistochemistry, the infiltrates were mainly CD4+ T cells during aGVHD onset, but CD8+ T cells predominated during aGVHD progression. Lung TNF-alpha and IFN-gamma levels were higher in the three experimental groups than in normal controls on days +3 and +7 post-transplant. On day +7, TNF-alpha levels were higher in allogeneic than in syngeneic transplant mice; IFN-gamma levels were not different. On days +12 and +16, TNF-alpha levels were higher but IFN-gamma levels were lower in allogeneic mice than in syngeneic transplant mice.

CONCLUSIONS

The underlying cause of IPS is aGVHD. T cells and TNF-alpha may play a role in the pathogenesis of aGVHD-induced IPS. IPS progression may be associated with decreasing lung IFN-gamma levels.

Paradoxical effects of IFN-gamma in graft-versus-host disease reflect promotion of lymphohematopoietic graft-versus-host reactions and inhibition of epithelial tissue injury

Interferon-gamma (IFN-gamma) inhibits graft-versus-host disease (GVHD) in lethally irradiated mice receiving allogeneic hematopoietic cell transplantation (allo-HCT) but promotes lethality in unirradiated and sublethally irradiated recipients. We investigated the role of IFN-gamma in GVHD in sublethally irradiated B6D2F1 recipients of B6 allo-HCT. B6D2F1 mice receiving wild-type B6 splenocytes alone died rapidly, whereas those receiving wild-type B6 splenocytes plus marrow survived long-term. Mice in both groups showed rapid elimination of host hematopoietic cells but minimal parenchymal tissue injury. However, mice receiving allo-HCT from IFN-gamma-deficient donors died rapidly regardless of whether donor marrow was given, and they exhibited severe parenchymal injury but prolonged survival of host hematopoietic cells. IFN-gamma plays a similar role in another model involving delayed B6 donor leukocyte infusion (DLI) to established mixed allogeneic (B6-->BALB/c) chimeras. IFN-gamma promotes DLI-mediated conversion from mixed to full donor chimerism while attenuating GVHD. Importantly, IFN-gamma enhances graft-versus-leukemia (GVL) effects in both models. Our data indicate that previously reported IFN-gamma-induced early mortality in allo-HCT recipients is due to augmentation of lymphohematopoietic graft-versus-host reaction (LGVHR) and can be avoided by providing an adequate source of donor hematopoietic stem/progenitor cells. Furthermore, the magnitude of GVL is correlated with the strength of LGVHR, and IFN-gamma reduces the potential of this alloreactivity to cause epithelial tissue GVHD.

An essential role for IFN-gamma in regulation of alloreactive CD8 T cells following allogeneic hematopoietic cell transplantation

We previously found that CD8 T cells from IFN-gamma gene knockout (GKO) donors induce more severe lethal GVHD compared with CD8 T cells from wild-type (WT) donors in fully MHC-mismatched strain combinations. In this study, we investigated the mechanisms by which IFN-gamma inhibits GVHD in a parent --> F1 (B6 --> B6D2F1) allogeneic HCT (allo-HCT) model. IFN-gamma was strongly protective against GVHD in this parent --> F1 haplotype-mismatched allo-HCT model. Irradiated B6D2F1 mice that received GKO B6 CD4-depleted splenocytes developed lethal GVHD with severe lung and liver injury, whereas those receiving a similar cell population from WT B6 donors survived long term. Donor CD8 cells showed rapid activation, accelerated cell division, and reduced/delayed activation-induced cell death in allogeneic recipients in which donor cells were incapable of producing IFN-gamma. In consequence, the numbers of activated/effector (ie, CD25+, CD62L-, and CD44(high)) donor CD8 T cells in the recipients of GKO allo-HCT significantly exceeded those in mice receiving WT allo-HCT. These data show that IFN-gamma negatively regulates the CD8 T cell response by inhibiting cell division and promoting cell death and suggest that blockade of IFN-gamma could augment the severity of GVHD in patients undergoing allo-HCT.

Cytokine Gene Expression in Peripheral Blood Mononuclear Cells and Alloreactivity in Hematopoietic Cell Transplantation with Nonmyeloablative Conditioning

Cytokines are thought to play an important role in the pathophysiology of graft-versus-host disease (GVHD). To study the relationship between cytokines and GVHD, we obtained peripheral blood mononuclear cells (MNCs) from 21 patients with hematologic malignancies and their HLA-identical sibling donors before and sequentially after hematopoietic cell transplantation (HCT) with nonmyeloablative conditioning. The MNCs were cultured for 72 hours either alone or in mixed lymphocyte cultures with irradiated MNCs of recipient, donor, or HLA-mismatched third-party origin. The gene expression of interleukin (IL)-2, IL-4, IL-10, IL-18, tumor necrosis factor alpha, and transforming growth factor beta in each culture was then measured by real-time quantitative reverse transcriptase-polymerase chain reaction. The composition of the responder MNCs differed between patients and donors and changed after HCT, with a possible influence on the results. Early after transplantation (day +14), the IL-10 messenger RNA (mRNA) level in response to recipient or donor antigens was higher in patients who did not develop clinically significant acute GVHD when compared with the level in patients who subsequently developed acute GVHD grades II to IV (P = .005 and P = .004, respectively). The IL-10 mRNA level on day +14 was highly correlated with the pretransplantation mRNA level of the recipient MNCs but not with the level of the donor MNCs; this suggests that the IL-10 mRNA detected on day +14 originated from responder cells of recipient origin. A higher IL-10 mRNA level was found in MNCs obtained before transplantation from recipients whose disease progressed or relapsed after the transplantation when compared with the level in patients whose disease did not progress or relapse (P = .03). In conclusion, a high IL-10 gene expression in the recipient MNCs may be related to a reduced incidence of acute GVHD grades II to IV and a reduced graft-versus-tumor effect after HCT with nonmyeloablative conditioning.

Kinetics of cytokine gene expression in human CD4+ and CD8+ T-lymphocyte subsets using quantitative real-time PCR

The time kinetics of five cytokines [interleukin-2 (IL-2), IL-5, interferon-gamma (IFN-gamma), granulocyte macrophage-colony stimulating factor (GM-CSF) and tumour necrosis factor-alpha (TNF-alpha)] and one cytotoxic effector protein (granzyme B) was analysed by real-time quantitative polymerase chain reaction (PCR) following in vitro stimulation of human CD4 and CD8 T lymphocytes. Two stimuli were used, a mitogen [phytohemagglutinin (PHA)] and a recall antigen [purified protein derivative (PPD)]. The pattern of cytokine mRNA expression was found to be dependent on the T-cell subset and stimulus used. A wide interindividual variability in the cytokine gene expression pattern was demonstrated. Two expression patterns were observed. A bell-shaped expression profile was seen for most cytokines upon PHA activation in both subsets and PPD-activated CD4 T cells, whereas a biphasic/multiphasic expression pattern was noted in CD8 T cells upon PPD stimulation. For most cytokines, the time to induction was within 30 min of activation, and maximum accumulation seemed to be obtained after 4-8 h of activation. A sustained high level could, however, be noticed for up to 24 h. Granzyme B gene expression was also induced within 30 min of activation but showed a continuous gradual increase and late maximal accumulation (48-72 h). The findings of the present study are of importance when designing studies using the cytokine gene expression profile as a marker for antigen-specific T lymphocytes. It might be recommended that cytokine gene expression (IL-2, IL-5 and IFN-gamma) should be measured after 4-8 h of specific activation but also up to 24 h of stimulation is acceptable. Granzyme B should preferentially be measured after 48-72 h of activation.

IFN-gamma and TNF-alpha production in gamma-irradiated blood units by mononuclear cells and GVHD prevention

Gamma-radiation of blood products is considered the mainstay of transfusion-associated graft-versus-host disease prevention. Previous studies have detected lymphocyte inhibition rate in blood components just one time after irradiation but there is evidence of cellular variability with production of cytokines at different storage time which could be related with irradiation activity and cellular damage repair. IFN-gamma, a Th1 cytokine, and TNF-alpha, a pro-inflammatory one, had a central role in the stimulation of cellular and inflammatory reactions. In this study whole blood was collected from five volunteer healthy donors and each donor bag was divided into two satellite bags: one of them was exposed to 137Cs-irradiation with a 2500 cGy dose. Samples for cytokine production, detected by ELISA methods, and proliferative response, evaluated by incorporation of H3 thymidine, were taken at the following storage time: 0, 24, 48, 72 and 96 h. The time-response curve of irradiated mononuclear cells from blood bags (BBMC) in mitogenic activation showed a time-related inhibition of cell proliferation with an enhanced response only after 24 h of storage and about 84% inhibition at 96 h. A similar pattern is follow by IFN-gamma production after OKT3 stimulation. TNF-alpha levels both in lipopolysaccharide stimulated or unstimulated cells were always high. This data suggest that BBMC cells maintain the ability to produce cytokines after gamma-radiation. On the ground of this study seems to be necessary to evaluate hypothetical risk associated with the administration of cytokine via irradiated blood components.