Serum levels of cytokines and secondary messages after T-cell-depleted and non-T-cell-depleted bone marrow transplantation: influence of conditioning and hematopoietic reconstitution

CNS macrophages and peripheral myeloid cells in brain tumours

Primary brain tumours (gliomas) initiate a strong host response and can contain large amounts of immune cells (myeloid cells) such as microglia and tumour-infiltrating macrophages. In gliomas the course of pathology is not only controlled by the genetic make-up of the tumour cells, but also depends on the interplay with myeloid cells in the tumour microenvironment. Especially malignant gliomas such as glioblastoma multiforme (GBM) are notoriously immune-suppressive and it is now evident that GBM cells manipulate myeloid cells to support tumour expansion. The protumorigenic effects of glioma-associated myeloid cells comprise a support for angiogenesis as well as tumour cell invasion, proliferation and survival. Different strategies for inhibiting the pathological functions of myeloid cells in gliomas are explored, and blocking the tropism of microglia/macrophages to gliomas or manipulating the signal transduction pathways for immune cell activation has been successful in pre-clinical models. Hence, myeloid cells are now emerging as a promising target for new adjuvant therapies for gliomas. However, it is also becoming evident that some myeloid-directed glioma therapies may only be beneficial for distinct subclasses of gliomas and that a more cell-type-specific manipulation of either microglia or macrophages may improve therapeutic outcomes.

Interleukin-6 modulates graft-versus-host responses after experimental allogeneic bone marrow transplantation

PURPOSE

The graft-versus-tumor (GVT) effect is a potent form of immunotherapy against many hematologic malignancies and some solid tumors. The beneficial GVT effect after allogeneic bone marrow transplantation (BMT) is tightly linked to its most significant complication, graft-versus-host disease (GVHD). The role of interleukin-6 (IL-6) after allogeneic BMT is not well understood. This study used a series of complementary knockout and antibody blockade strategies to analyze the impact of IL-6 in multiple clinically relevant murine models of GVHD and GVT.

EXPERIMENTAL DESIGN

We examined the effect of the source of IL-6 by analyzing the role IL-6 deficiency in donor T cells, donor bone marrow or in host tissues. We confirmed and extended the relevance of IL-6 deficiency on GVHD and GVT by treating BMT recipients with anti-mouse IL-6 receptor (IL-6R), MR16-1.

RESULTS

Deficiency of IL-6 in donor T cells led to prolongation of survival. Total inhibition of IL-6 with MR16-1 caused an even greater reduction in GVHD-induced mortality. The reduction in GVHD was independent of the direct effects on T effector cell expansion or donor regulatory T cells. GVT responses were preserved after treatment with MR16-1.

CONCLUSION

MR16-1 treatment reduced GVHD and preserved sufficient GVT. Tocilizumab, a humanized anti-IL-6R monoclonal antibody (mAb), is approved in several countries including the United States and European Union for the treatment of rheumatoid arthritis and other inflammatory diseases. Blockade of IL-6 with anti-IL-6R mAb therapy may be testable in clinical trials as an adjunct to prevent GVHD in BMT patients without a significant loss of GVT.

Delaying DLA-haploidentical hematopoietic cell transplantation after total body irradiation

Exposure to accidental or deliberate radiation poses a threat to public health, proving lethal at higher doses in large part because of deleterious effects on marrow. In those cases, allogeneic hematopoietic cell transplantation (HCT) might be required to restore marrow function. Most radiation accident victims will have HLA-haploidentical relatives who could serve as HCT donors. Here, we assessed in a canine HCT model the total body irradiation (TBI) doses after which transplants might be required and successful engraftment would be possible. In an attempt at mimicking the logistical problems likely to exist after radiation accidents, 4-, 8- or 10-day intervals were placed between TBI and HCT. To keep the experimental readout simple, no graft-versus-host disease (GVHD) prevention was administered. All dogs transplanted after a 4-day delay following 700 or 920 cGy TBI successfully engrafted, whereas virtually all those given 450 or 600 cGy rejected their grafts. Transplant delays of 8 and 10 days following 920 cGy TBI also resulted in successful engraftment in most dogs, whereas a delay of 8 days after 700 cGy resulted in virtually uniform graft failure. The time courses of acute GVHD (aGVHD) and rates of granulocyte recovery in engrafting dogs were comparable among dogs regardless of the lengths of delay. In other studies, we showed that most dogs not given HCT survived 700 cGy TBI with intensive supportive care, whereas those given 800 cGy TBI and higher died with marrow aplasia. Thus, DLA-haploidentical HCT was successful even when carried out 4, 8, or 10 days after TBI at or above radiation exposures where dogs survived with intensive care alone.

A sequential scanning of the immune efficiency in astrocytoma (Grade I to Grade Iii), meningioma and secondary glioma patients with and without therapeutic scheduling

PURPOSE

Glioma induces immune suppression. However, data revealing the immune status in glioma patients with sequential therapeutic interventions is missing. Thus, the study aims at evaluating the sequential immune status of glioma bearing patients (Astrocytoma Grade I to Grade III) receiving conventional therapeutic measures. The results were compared with the immune status of metastatic secondary glioma and meningioma patients where there is minimal immune suppression and the effect of therapeutic intervention on the above score.

METHODS

Functional immune parameters of peripheral blood lymphocytes were assayed by CD2 receptors enumeration through E-rosetting and lymphocyte cytotoxicity assay and assessing the generation of reactive oxygen species by NBT assay of peripheral blood macrophages in patient groups bearing Astrocytoma (Grade I to Grade III), meningioma and secondary glioma.

RESULTS

Patients bearing Astrocytoma (all 3 grades) showed maximum immune suppression as compared to the normal subjects, diseased meningioma controls, and secondary glioma. Therapeutic interventions viz. radiotherapy, surgery and radiotherapy after surgery and chemotherapy could not recover the suppressed activity of the CD2 bearing lymphocytes and that of peripheral blood macrophages. However, therapeutic scheduling could recover the functional activity of the CD8 bearing lymphocytes and the CD56 NK cells from that of tumor bearing patients.

CONCLUSION

Astrocytoma and not meningioma is capable of causing immunesuppression. As the tumor progresses from Grade I to Grade III, a linear reduction in the functional efficacy of immunocytes is seen to occur. Radiotherapy, surgery, and chemotherapy also induces an inhibitory effect towards the host immune system. The inhibitory effect of tumor as well as of therapy were mainly directed towards the CD2 bearing lymphocyte population and the peripheral blood macrophage population.

Delayed or delayed sequential bone marrow transplantation: relevance for acute graft-versus-host disease prevention after major H2 incompatible transplantation

During this study, BalB/C mice were used as recipients and C57 bl/6 mice as donors. Recipients were given 800 cGys of total body irradiation (TBI) on day 0. Transplantation was carried out as follows: group (1): TBI on day 0; group (2): TBI on day 0 and transplantation on day +1; group (3): TBI on day 0 and transplantation on day 4; group (4): TBI on day 0 and transplantation started from day 4 through day 8. Mice that received TBI only died by day 11. All group 2 mice developed aGVHD and died by day +15. In total, 70% of group 3 were still surviving by day 60 (P<0.001, compared to day +1 transplantation). Survival rates were 90% at day 60 for group 4 (P<0.001 compared to day 1 transplantation). No survival advantage was found between animals transplanted on day 4 and animals with delayed sequential transplantation (P=0.1). Significant engraftment was found in both groups 3 and 4, with no significant differences in the percentages of donor-derived cells between the two groups (P>0.05). These data demonstrate that either delayed or delayed sequential transplantation after TBI can be an effective approach for aGVHD prevention.

Limb lymph node response to bone fracture

In previous clinical studies, dilation of afferent lymphatics and enlargement of inguinal lymph nodes (LN) were observed in lymphoscintigrams from patients with persistent posttraumatic edema of lower extremities after fractures and trauma of soft tissues. In this study, changes in rat popliteal and iliac lymph nodes draining lymph from the site of tibial fracture and adjacent soft tissue injury were investigated. The observed parameters were lymph node weight, cell number, phenotype frequency, cell cytokine expression, and reactivity to mitogens. The key observations included: a) increase in the weight and total cell number of the lymph nodes; b) increased autotransformation rate and responsiveness of lymph node cells to mitogen; c) decreased frequency of ED1 macrophages and activated OX8 cytotoxic cells in flow cytometry analysis; d) high expression of OX6 class II-positive, OX7 (stem cells), OX62 (migrating dendritic cells), ED1 (macrophages), and OX12 (B cells) on immunohistochemical sections of LNs with some few HIS48 (granulocytes); e) high expression of NOS3 and TGF beta by lymph node lymphocytes and endothelial cells. In summary, local lymph nodes reacted to internal wounds, such as bone fracture and injury to adjacent tissues, through mobilization of cells from the blood circulation, along with activation of cellular subsets. The molecular mechanism that provides the signal for this reaction remains unknown. The absence of major changes in the frequency of lymph node cell subpopulations indicates that lymph nodes are constitutively prepared for influx of antigens from damaged tissues and react only with increase in cell number and cell activation. The nature of the reaction, including lack of immunization against autoantigens, remains unclear. Further elucidation will require studies on the mechanism of cross-tolerance to self-antigens during wound healing.

Induction of Tolerance in Quadruple Chimeric Mice

Human cord blood (CB) contains hematopoietic stem cells and progenitors. Because the major limitation to a widespread use of CB for transplantation lies in its limited volume, it is necessary to combine the CB from several donors. In this study, we show that lethally irradiated mice can be reconstituted with the injection of a mixture of T cell-depleted bone marrow cells (BMCs; total, 3 x 10(6)) obtained from three fully allogeneic mouse strains in two different mouse combinations. A higher survival rate was obtained in the triple injection group than in mice injected with BMCs (1 x10(6)) obtained from a single mouse strain. In the mixed chimeric mice, three kinds of donor-type and recipient-type cells were detected in all the hematopoietic organs 1 month after bone marrow transplantation (BMT). Mixed-lymphocyte reaction showed that the tolerance to both recipient-type and donor-type major histocompatibility complex determinants was induced in the chimeric mice. In the peripheral blood (PB) of these mice, only one type of cells from the three different donor strains became dominant in most chimeric mice and reached a stable level about 4 months after BMT. Polymerase chain reaction analyses, however, revealed that the skins from all the donors were accepted even when no cells with their phenotypes could be detected in the PB. These results suggest that both hemato-lymphoid reconstitution and stable tolerance to not only the recipient strain but also all the donor strains can be achieved in chimeric mice, indicating the possibility of mixed CB transplantation in humans.

The pathomechanism of posttraumatic edema of lower limbs: I. The effect of extravasated blood, bone marrow cells, and bacterial colonization on tissues, lymphatics, and lymph nodes

BACKGROUND

The mechanical injury of soft tissues and bones of lower extremities is frequently followed by long-lasting edema at the site of trauma and distally. The pathomechanism of this complication remains unclear. Venous thrombosis and interruption of lymphatics are considered to be the main etiologic factors. We propose a concept that protracted healing of injured tissues and bones with involvement of the regional lymphatic system (lymphatics and nodes) is responsible for persistence of edema. The events affecting the first (scavenging) phase of healing of traumatized tissues, such as hematoma, translocation of bone marrow cells to soft tissues, and colonization by microorganisms, and in particular their effects on lymphatics and lymph nodes, were studied.

METHODS

Mongrel dogs weighing 15-20 kg were used. Fresh blood or bone marrow cell (BMC) suspension was injected subcutaneously or intralymphatically into the paw. Strains of saprophyte bacteria residing on the skin surface were cultured and injected intradermally. Oil-contrast lymphography was performed before and after injections to evaluate the changes in lymphatics and nodes. Biopsy samples of paw skin, subcutaneous tissue, and regional lymph nodes (LN) were taken. The responsiveness of LN lymphocytes was studied in autologous mixed cultures with peripheral blood lymphocytes (PBL), BMC, and cultured bacteria.

RESULTS

The PBL from subcutaneously injected blood were evacuated by the lymphatic route at a rate of 1-3%/6 hr. There was no thrombosis of lymphatic vessels or obstruction of LN sinusoids. The BMC evoked major inflammatory changes in both the skin and the LN. Bacteria caused local inflammation, dilatation of lymphatics, and destruction of node parenchyma. Autologous BMC and PBL stimulated LN lymphocytes in a 6-day culture. The responsiveness of lymph node lymphocytes to previously subcutaneously injected bacterial antigens was increased.

CONCLUSION

The extravasated blood did not produce changes in skin, subcutaneous tissue, and lymphatics; however, it stimulated LN lymphocytes. The BMC and saprophyte bacteria caused major local and lymph node inflammatory response. All these factors may contribute to the local edema in the initial phases of healing of traumatized tissues.

Administration of granulocyte colony-stimulating factor induces hyporesponsiveness to lipopolysaccharide and impairs antigen-presenting function of peripheral blood monocytes

OBJECTIVE

The incidence and severity of acute graft-vs-host disease after allogeneic transplantation of granulocyte colony-stimulating factor (G-CSF)-mobilized peripheral blood stem cells (PBSC) are not greater than those after conventional bone marrow transplantation despite infusion of more than one log greater number of donor T cells in PBSC. It has been postulated that monocytes from G-CSF-mobilized donors suppress alloreactivity of donor T cells.

MATERIALS AND METHODS

We investigated the phenotype and function of monocytes in normal individuals receiving 10 microg/kg of G-CSF for 4 days.

RESULTS

Monocytes were phenotypically and functionally different after G-CSF administration from steady-state monocytes. They were characterized by an increased CD14(+)CD16(+) subpopulation, reduced expression of HLA-DR, and diminished ability to produce tumor necrosis factor-alpha and interleukin-10 to lipopolysaccharide, compared with steady-state monocytes. These alterations were not replicated by culturing monocytes with G-CSF in vitro, suggesting an indirect effect of G-CSF. In addition, the antigen-presenting function of G-CSF-mobilized monocytes was impaired.

CONCLUSION

Hyporesponsiveness of G-CSF-treated monocytes to lipopolysaccharide with regard to tumor necrosis factor-alpha production, together with impaired antigen-presenting function, may be responsible for the unexpectedly low incidence of graft-vs-host disease after G-CSF-mobilized PBSC transplantation.

Mucosal barrier injury: biology, pathology, clinical counterparts and consequences of intensive treatment for haematological malignancy: an overview

Mucositis is an inevitable side-effect of the conditioning regimens used for haematopoietic stem cell transplantation. The condition is better referred to as mucosal barrier injury (MBI) since it is primarily the result of toxicity and is a complex and dynamic pathobiological process manifested not only in the mouth but also throughout the entire digestive tract. A model has been proposed for oral MBI and consists of four phases, namely inflammatory, epithelial, ulcerative and healing phases. A variety of factors are involved in causing and modulating MBI including the nature of the conditioning regimen, the elaboration of pro-inflammatory and other cytokines, translocation of the resident microflora and their products, for example, endotoxins across the mucosal barrier, exposure to antimicrobial agents and whether or not the haematopoietic stem cell graft is from a donor. Neutropenic typhlitis is the most severe gastrointestinal manifestation of MBI, but it also influences the occurrence of other major transplant-related complications including acute GVHD, veno-occlusive disease and systemic infections. The pathobiology, clinical counterparts and the means of measuring MBI are discussed together with potential approaches for prevention, amelioration and, perhaps, even cure. Bone Marrow Transplantation (2000) 25, 1269-1278.

Differential roles of IL-1 and TNF-alpha on graft-versus-host disease and graft versus leukemia

We demonstrate an increase in graft-versus-host disease (GVHD) after experimental bone marrow transplant (BMT) when cyclophosphamide (Cy) is added to an otherwise well-tolerated dose (900 cGy) of total body irradiation (TBI). Donor T cell expansion on day +13 was increased after conditioning with Cy/TBI compared with Cy or TBI alone, although cytotoxic T lymphocyte (CTL) function was not altered. Histological analysis of the gastrointestinal tract demonstrated synergistic damage by Cy/TBI and allogeneic donor cells, which permitted increased translocation of LPS into the systemic circulation. TNF-alpha and IL-1 production in response to LPS was increased in BMT recipients after Cy/TBI conditioning. Neutralization of IL-1 significantly reduced serum LPS levels and GVHD mortality, but it did not affect donor CTL activity. By contrast, neutralization of TNF-alpha did not prevent GVHD mortality but did impair CTL activity after BMT. When P815 leukemia cells were added to the bone marrow inoculum, allogeneic BMT recipients given the TNF-alpha inhibitor relapsed at a significantly faster rate than those given the IL-1 inhibitor. To confirm that the role of TNF-alpha in graft versus leukemia (GVL) was due to effects on donor T cells, cohorts of animals were transplanted with T cells from either wild-type mice or p55 TNF-alpha receptor-deficient mice. Recipients of TNF-alpha p55 receptor-deficient T cells demonstrated a significant impairment in donor CTL activity after BMT and an increased rate of leukemic relapse compared with recipients of wild-type T cells. These data highlight the importance of conditioning in GVHD pathophysiology, and demonstrate that TNF-alpha is critical to GVL mediated by donor T cells, whereas IL-1 is not.

Tumor necrosis factor- alpha production to lipopolysaccharide stimulation by donor cells predicts the severity of experimental acute graft-versus-host disease

Donor T cell responses to host alloantigen are known predictors for graft-versus-host disease (GVHD); however, the effect of donor responsiveness to an inflammatory stimulus such as lipopolysaccharide (LPS) on GVHD severity has not been investigated. To examine this, we used mouse strains that differ in their sensitivity to LPS as donors in an experimental bone marrow transplant (BMT) system. Lethally irradiated (C3FeB6)F1 hosts received BMT from either LPS-sensitive (LPS-s) C3Heb/Fej, or LPS-resistant (LPS-r) C3H/ Hej donors. Mice receiving LPS-r BMT developed significantly less GVHD as measured by mortality and clinical score compared with recipients of LPS-s BMT, a finding that was associated with significant decreases in intestinal histopathology and serum LPS and TNF-alpha levels. When donor T cell responses to host antigens were measured, no differences in proliferation, serum IFN-gamma levels, splenic T cell expansion, or CTL activity were observed after LPS-r or LPS-s BMT. Systemic neutralization of TNF-alpha from day -2 to +6 resulted in decreased intestinal pathology, and serum LPS levels and increased survival after BMT compared with control mice receiving Ig. We conclude that donor resistance to endotoxin reduces the development of acute GVHD by attenuating early intestinal damage mediated by TNFalpha. These data suggest that the responsiveness of donor accessory cells to LPS may be an important risk factor for acute GVHD severity independent of T cell responses to host antigens.

Delaying transplantation after total body irradiation is a simple and effective way to reduce acute graft-versus-host disease mortality after major H2 incompatible transplantation

BACKGROUND

We have previously reported that delaying histoincompatible transplantation after total body irradiation (TBI) conditioning markedly decreased the mortality of acute graft-versus-host disease (GVHD) in severe combined immunodeficiency mice. However, it was not clear whether the delayed transplantation would affect the final engraftment and acute GVHD mortality in normal hosts.

METHODS

BALB/c mice (H2d) were lethally irradiated with 8.5 Gy TBI and transplanted with C57BL/6 (H2d) bone marrow plus spleen cells on the same day (TBI+day 0) or 4 days after TBI conditioning (TBI+day 4).

RESULTS

We again demonstrated that delaying transplantation by 4 days after TBI conditioning markedly reduced acute GVHD mortality in normal hosts after major histoincompatible transplantation. The survival rates were 66% in TBI+day 4 vs. 0% in TBI+day 0 allogeneic transplanted animals by day +60 (P<0.001). Further analysis demonstrated that the 4-day rest between the TBI and allogeneic transplantation broke the interaction of cell/inflammatory tumor necrosis factor-alpha, interleukin (IL)-1beta, and IL-6 cytokine reactions stimulated by TBI and incompatible transplantation. Flow cytometry revealed 97% donor cells in host marrow by 2 weeks in TBI+day 0 transplantation versus 57% in TBI+day 4 transplantation. There was no difference in percentage of donor CD3+ T-cell engraftment between the TBI+day 0 and TBI+day 4 allogeneic transplanted animals. In TBI+day 4 transplantation, the percentage of donor cells in host marrow steadily increased to 74% by day +60 and 93% by day +100.

CONCLUSIONS

This 2- to 3-month early mixed chimerism in TBI+day 4 transplanted animals might be related to lower levels of tumor necrosis factor-alpha and IL-6 both of which have been shown to stimulate lymphohematopoiesis and was associated with lower acute GVHD mortality. The data again demonstrated in immunologically normal BALB/c mice that delaying allogeneic transplantation after TBI is a simple and effective way to reduce acute GVHD mortality, achieve satisfactory engraftment and significantly increase overall survival.