Murine T Lymphocytes Incapable of Producing Macrophage Inhibitory Protein-1 Are Impaired in Causing Graft-Versus-Host Disease Across a Class I But Not Class II Major Histocompatibility Complex Barrier

Advantage of First-Line Therapeutic Drug Monitoring-Driven Use of Infliximab for Treating Acute Intestinal and Liver GVHD in Children: A Prospective, Single-Center Study

The high serum concentrations of TNF-α characterize acute graft-versus-host disease (aGVHD), for which infliximab treatment may be beneficial. In 28 pediatric patients, four doses of 10 mg/kg infliximab every seven days were administered after steroid failure (Standard Group, n = 14) or as a first-line therapy (Early Group, n = 14). Population pharmacokinetic analyses and evaluation of serum cytokines were performed. After two months of treatment, complete response in gastrointestinal and liver aGVHD was achieved in 43% and 100% of patients in the Standard and Early groups, respectively. During follow-up, four patients in the Standard Group (but none in the Early Group) experienced an aGVHD recurrence. Viral infections occurred more frequently in the Standard Group after the fifth dose. Infliximab clearance did not differ between groups or according to treatment outcome for each organ involved in aGVHD, whereas serum levels of cytokines significantly differed. Therefore, present findings show that use of first-line, TDM-driven infliximab to treat aGVHD in children may result in better clinical outcomes and tolerability, with a different pattern of cytokines generated according to the moment of beginning of treatment.

Involvement of ocular surface in graft-versus-host disease: An update from immunopathogenesis to treatment

Graft-versus-host disease is a common complication of hematopoietic stem cell transplantation and the ocular surface is a main target of inflammatory reaction.

Alterations in chemokine receptor CCR5 expression on blood dendritic cells correlate with acute graft-versus-host disease

BACKGROUND

Dendritic cells (DC) are important in the development of acute graft-versus-host disease (GVHD) after allogeneic hemopoietic cell transplantation (alloHCT). The trafficking of immature DC from blood to GVHD target organs is likely to be regulated by chemokine receptors.

METHODS

We performed flow cytometry to document the expression of chemokine receptors on circulating DC and correlated the findings after alloHCT with occurrence of acute GVHD.

RESULTS

In normal individuals, plasmacytoid DC (pDC) expressed high levels of CCR5, whereas the major CD16 myeloid DC subpopulation lacked CCR5. However, its expression on CD16 cells was induced by culture in allogeneic mixed lymphocyte reaction supernatant, an effect largely mediated by interferon-γ. CCR5 was expressed on a significant proportion of CD16 DC in 42 alloHCT patients, whereas it was down-regulated on pDC. The maximum percentage of CCR5CD16 DC, at any time after transplantation, correlated with acute GVHD, whereas the minimum CCR5 on pDC showed a similar correlation. Before developing signs of GVHD, the maximum percentage CCR5CD16 DC was higher in patients with GVHD grades II to IV than in GVHD grades 0 and I, whereas the minimum percentage CCR5 on pDC was lower in GVHD grades II to IV than in GVHD grades 0 and I. CCR5 levels more than 20.5% on CD16 myeloid DC and less than 22.6% on CD123 pDC correlated with subsequent GVHD grades II to IV with high sensitivities and specificities.

CONCLUSIONS

These observations may reflect DC activation and altered homing during the alloimmune response and could allow early diagnosis and therapeutic intervention before the clinical diagnosis of GVHD.

Chemokines in chronic liver allograft dysfunction pathogenesis and potential therapeutic targets

Despite advances in immunosuppressive drugs, long-term success of liver transplantation is still limited by the development of chronic liver allograft dysfunction. Although the exact pathogenesis of chronic liver allograft dysfunction remains to be established, there is strong evidence that chemokines are involved in organ damage induced by inflammatory and immune responses after liver surgery. Chemokines are a group of low-molecular-weight molecules whose function includes angiogenesis, haematopoiesis, mitogenesis, organ fibrogenesis, tumour growth and metastasis, and participating in the development of the immune system and in inflammatory and immune responses. The purpose of this review is to collect all the research that has been done so far concerning chemokines and the pathogenesis of chronic liver allograft dysfunction and helpfully, to pave the way for designing therapeutic strategies and pharmaceutical agents to ameliorate chronic allograft dysfunction after liver transplantation.

Stromal interferon-γ signaling and cross-presentation are required to eliminate antigen-loss variants of B cell lymphomas in mice

To study mechanisms of T cell-mediated rejection of B cell lymphomas, we developed a murine lymphoma model wherein three potential rejection antigens, human c-MYC, chicken ovalbumin (OVA), and GFP are expressed. After transfer into wild-type mice 60–70% of systemically growing lymphomas expressing all three antigens were rejected; lymphomas expressing only human c-MYC protein were not rejected. OVA expressing lymphomas were infiltrated by T cells, showed MHC class I and II upregulation, and lost antigen expression, indicating immune escape. In contrast to wild-type recipients, 80–100% of STAT1-, IFN-γ-, or IFN-γ receptor-deficient recipients died of lymphoma, indicating that host IFN-γ signaling is critical for rejection. Lymphomas arising in IFN-γ- and IFN-γ-receptor-deficient mice had invariably lost antigen expression, suggesting that poor overall survival of these recipients was due to inefficient elimination of antigen-negative lymphoma variants. Antigen-dependent eradication of lymphoma cells in wild-type animals was dependent on cross-presentation of antigen by cells of the tumor stroma. These findings provide first evidence for an important role of the tumor stroma in T cell-mediated control of hematologic neoplasias and highlight the importance of incorporating stroma-targeting strategies into future immunotherapeutic approaches.

PI3Kγ controls leukocyte recruitment, tissue injury, and lethality in a model of graft-versus-host disease in mice

PI(3)Kγ is thought to mediate leukocyte migration to injured tissues and may be important in the pathogenesis of various T-lymphocyte-dependent pathologies, including autoimmune and inflammatory diseases. The present study evaluated the relevance of PI(3)Kγ in donor cells for the pathogenesis of acute GVHD using a model of adoptive transfer of splenocytes from WT or PI(3)Kγ(-/-) C57BL/6J mice to B6D2F1 mice, and mice that received PI(3)Kγ(-/-) cells showed reduced clinical signs of disease, bacterial translocation, tissue injury, and lethality rates. This was associated with reduced production of proinflammatory cytokines and chemokines (TNF-α, IFN-γ, CCL2, CCL3, and CCL5) and reduced infiltration of CD8(+), CD4(+), and CD11c(+) cells in the small intestine. Mechanistically, in addition to decreasing production of proinflammatory mediators, absence or pharmacological blockade of PI(3)Kγ was associated with decreased rolling and adhesion of leukocytes to the mesenteric microcirculation, as assessed by intravital microscopy. Despite decreased GVHD, there was maintained GVL activity when PI(3)Kγ(-/-) leukocytes were transferred into WT mice. In conclusion, PI(3)Kγ plays a critical role in GVHD by mediating leukocyte influx and activation in tissues. PI(3)Kγ inhibitors may be useful in the treatment of GVHD in patients undergoing BMT.

The chemokine, CCL3, and its receptor, CCR1, mediate thoracic radiation-induced pulmonary fibrosis

Patients receiving thoracic radiation often develop pulmonary injury and fibrosis. Currently, there are no effective measures to prevent or treat these conditions. We tested whether blockade of the chemokine, CC chemokine ligand (CCL) 3, and its receptors, CC chemokine receptor (CCR) 1 and CCR5, can prevent radiation-induced lung inflammation and fibrosis. C57BL/6J mice received thoracic radiation, and the interaction of CCL3 with CCR1 or CCR5 was blocked using genetic techniques, or by pharmacologic intervention. Lung inflammation was assessed by histochemical staining of lung tissue and by flow cytometry. Fibrosis was measured by hydroxyproline assays and collagen staining, and lung function was studied by invasive procedures. Irradiated mice lacking CCL3 or its receptor, CCR1, did not develop the lung inflammation, fibrosis, and decline in lung function seen in irradiated wild-type mice. Pharmacologic treatment of wild-type mice with a small molecule inhibitor of CCR1 also prevented lung inflammation and fibrosis. By contrast, mice lacking CCR5 were not protected from radiation-induced injury and fibrosis. The selective interaction of CCL3 with its receptor, CCR1, is critical for radiation-induced lung inflammation and fibrosis, and these conditions can be largely prevented by a small molecule inhibitor of CCR1.

Chemokine receptor CCR5 mediates alloimmune responses in graft-versus-host disease

Allogeneic bone marrow transplantation (BMT) is an effective therapy for hematologic malignancies. However graft-versus-host disease (GVHD) is a major limiting factor for a successful patient outcome. GVHD is a result of alloimmune responses of donor T lymphocytes attacking the recipient's cells and tissues. Chemokine receptor CCR5 plays a role in solid organ allograft rejection and mediates murine GVHD pathogenesis. Herein, we report that infiltrating lymphocytes in the skin of human acute GVHD (aGVHD) samples are predominantly CCR5(+) T cells. In addition, we characterized the features of the CCR5 expression on alloreactive T lymphocytes. We found that the CCR5(+) population exhibits the characteristics of the activated effector T cell phenotype. CCR5 expression is upregulated upon allogenic stimulation, and CCR5(+) cells are proliferating with coexpression of T cell activation markers. Furthermore, the activated T cells producing inflammatory cytokine tumor necrosis factor (TNF)alpha, interleukin (IL)-2, or interferon (IFN)-gamma, are positive for CCR5. Thus, CCR5 is a marker for GVHD effector cells and CCR5(+) T cells are active participants in the pathogenesis of human aGVHD.

Differential chemokine expression in chronic GVHD of the conjunctiva

In chronic GVHD after BMT, the conjunctiva represents a target organ. GVHD can lead to severe inflammation and dry-eye syndrome (sicca syndrome). The molecular mechanisms are largely unknown. We examined the expression of chemokines in the conjunctiva in cases of chronic GVHD. In this study, we included 10 patients with chronic GVHD and 10 healthy controls. Clinical data were collected and tear film analysis and conjunctival cytology were carried out. Conjunctival biopsies were taken from all participants. Gene expression profiles of chemokines and their corresponding receptors were evaluated by means of quantitative real-time PCR. Chemokine protein expression was analysed by immunohistochemical analyses. Expressions of the Th1-associated chemokines, chemokine (C-X-C motif) ligand (CXCL) 9 (Mig), CXCL10 (IP-10), and their receptor chemokine (C-X-C motif) receptor 3 (CXCR3) were significantly increased in GVHD patients. Immunohistochemical analysis confirmed marked expression of the inflammatory CXCR3 ligands. A total of six patients had a moderate or severe sicca syndrome. Impression cytology revealed a mild keratinisation, moderate keratinisation or severe squamous metaplasia in three patients, respectively. Chronic GVHD of the conjunctiva is characterised by the expression of Th1-associated chemokines. Taken together, our results confirm that the conjunctiva is a target organ in this T cell-mediated process and add to molecular understanding of conjunctival GVHD.

The CCL3/macrophage inflammatory protein-1alpha-binding protein evasin-1 protects from graft-versus-host disease but does not modify graft-versus-leukemia in mice

CCL3 is a protein of the CC chemokine family known to be important for T cell recruitment in inflammatory diseases. The aim of the current study was to evaluate the effects and putative mechanism of action of evasin-1, a novel CCL3-binding protein, in the pathogenesis of acute graft-versus-host disease (GVHD). GVHD was induced by the transplantation of splenocytes from C57BL/6J to B6D2F1 mice. Treatment of recipient mice with evasin-1 prevented mortality associated with GVHD. This was correlated with reduced weight loss and clinical disease severity. Analysis of the small intestine showed that evasin-1 treatment reduced the histopathological score and decreased levels of IFN-gamma and CCL5. Mechanistically, evasin-1 treatment reduced the number of CD4(+) and CD8(+) T cells infiltrating the small intestine, as assessed by immunohistochemistry, and the adhesion of leukocytes to intestinal venules of recipient mice, as assessed by intravital microscopy. Evasin-1 was also able to decrease liver damage, as seen by reduction of inflammatory infiltrate and IFN-gamma levels. Treatment with evasin-1 did not interfere with graft-versus-leukemia. Altogether, our studies demonstrate that CCL3 plays a major role in mediating GVHD, but not graft-versus-leukemia in mice and suggest that blockade of CCL3 with evasin-1 has potential therapeutic application in patients undergoing bone marrow transplantation.

Predominant infiltration of monocytes in chronic graft-versus-host disease

Pathogenesis of chronic graft-versus-host disease (cGVHD) is largely unknown. It is important to determine the responsible cell types and the factors that play roles to recruit these cells into sites of disease. We examined whether monocytes and chemokine fractalkine/receptor CX3CR1 axis might be involved. We found that the absolute number of CX3CR1+ monocytes in the blood was significantly decreased in patients with severe cGVHD. Immunohistochemical staining revealed the extensive infiltration of CD14+ cells as well as strong expression of fractalkine in the cGVHD skin. The number of infiltrated CD14+ cells on the margin of fractalkine+ epidermis was larger in cGVHD skin compared to that of acute graft-versus-host disease, whereas no difference was observed in CD3+ T cells. These results suggest that CX3CR1+ monocytes may be recruited from the circulation to the fractalkine+ epidermis in cGVHD, and highlight these cells and this chemokine/receptor axis as additional targets for cGVHD therapy.

Expression of chemokines in GVHD target organs is influenced by conditioning and genetic factors and amplified by GVHR

Graft-versus-host disease (GVHD) is the most significant clinical problem that arises after allogeneic hematopoietic cell transplantation. Because chemokines induced by proinflammatory conditioning treatment may promote T-cell migration into GVHD target tissues, we addressed the influence of conditioning on chemokine expression in GVHD target organs. Our results showed that (1) conditioning leads to rapid and transient chemokine upregulation in GVHD target tissues before the time of GVHD-associated T-cell infiltration; (2) conditioning intensity and mouse strain influence chemokine expression in GVHD target organs; and (3) compared with syngeneic bone marrow transplantation, allogeneic bone marrow transplantation led to marked amplification of chemokine expression in GVHD target organs after myeloablative conditioning. This is also reflected by chemokine protein expression that is measured in the serum and colon. Intestines showed the greatest sensitivity to conditioning intensity, and chemokines affecting T-helper type 1 cells (eg, interferon gamma-inducible protein 10 [CXCL10]) were most strongly expressed there after conditioning and during GVHD. However, severity of GVHD was not significantly different between recipients of CXCR3+/+ or CXCR3-/- splenocytes, indicating that this chemokine pathway does not play a critical role. In summary, our data show that conditioning and recipient strain influence chemokine expression in GVHD target organs and that GVH alloreactivity markedly amplifies this expression, thus contributing to the inflammatory cascade associated with tissue GVHD.

Reduction of graft-versus-host disease by histone deacetylase inhibitor suberonylanilide hydroxamic acid is associated with modulation of inflammatory cytokine milieu and involves inhibition of STAT1

Histone deacetylase (HDAC) inhibitors reduce development of graft-versus-host disease (GVHD) following allogeneic bone marrow transplantation (BMT). Administration of the HDAC inhibitor suberonylanilide hydroxamic acid (SAHA) resulted in a significantly reduced GVHD-dependent mortality following fully major histocompatibility complex-mismatched allogeneic BMT. However, SAHA treatment did not affect T-cell activation or T-cell expansion in vitro and in vivo. Therefore, we focused on the effects of SAHA treatment on cytokine production and intracellular signaling events in vitro and in vivo following GVHD induction. Cultivation in the presence of SAHA broadly inhibited lipopolysaccharide (LPS) and alloantigen-induced cytokine/chemokine production in vitro and led also to a significant decrease in interferon-gamma and tumor necrosis factor-alpha levels in vivo following induction of GVHD. Concomitantly, SAHA treatment inhibited phosphorylation of STAT1 and STAT3 in response to LPS and alloactivation in vitro. Induction of GVHD led to a rapid phosphorylation of STAT 1 in the liver and spleen, which was markedly reduced by SAHA treatment. In conclusion, GVHD is associated with a marked induction of phosphorylation of STAT1 in the liver and spleen, and SAHA-dependent reduction of GVHD is associated with systemic and local inhibition of phosphorylated STAT1 and blunting proinflammatory cytokine production during the initiation phase of GVHD.

Shared biology of GVHD and GVT effects: Potential methods of separation

The difficult separation of clinical graft-versus-tumor (GVT) effects from graft-versus-host disease (GVHD) reflects their shared biology. Experimental approaches to mediate GVT effects while limiting GVHD include: (1) allograft T cell depletion followed by immune enhancement; (2) modulation of T cell dose or T cell subset composition; (3) donor lymphocyte infusion; (4) reduced-intensity host preparation; (5) modulation of Th1/Th2 and Tc1/Tc2 cell balance; (6) cytokine therapy or neutralization; (7) T regulatory cell therapy; (8) co-stimulatory pathway modulation; (9) chemokine pathway modulation; (10) induction of antigen-specific T cells; (11) alloreactive NK cell therapy; and (12) targeted pharmaceutical inhibition of proteosome, mammalian target of rapamycin, and histone deacetylase pathways. Clearly, a multitude of approaches exist that hold promise for separating GVT effects from GVHD. Future success in this endeavor will require a strong commitment towards translational research and continued advances in cell, vaccine, cytokine, monoclonal antibody, and targeted molecular therapy.

T Cells from Presensitized Donors Fail to Cause Graft-versus-Host Disease in a Pig-to-Mouse Xenotransplantation Model

BACKGROUND

The ability of T cells from pigs, the most suitable donors for clinical xenotransplantation, to induce graft-versus-host disease (GVHD) and to facilitate hematopoietic cell engraftment in highly disparate xenogeneic recipients remains unclear. In this article, the authors address these questions in a presensitized pig-to-mouse transplantation model using porcine cytokine-transgenic mice.

METHODS

Swine donors were presensitized by mouse skin grafting and boosted by the injection of mouse cells after the skin graft was rejected. Porcine peripheral blood mononuclear cells (PBMC) and splenocytes were collected at various times after mouse skin grafting, and their potential to induce GVHD and to facilitate donor hematopoietic cell engraftment in conditioned murine recipients was evaluated.

RESULTS

Presensitization of donor pigs resulted in marked enhancement of anti-mouse responses, as reflected in augmented anti-mouse mixed lymphocyte responses, cell-mediated cytotoxicity, and antibody production. However, injection of high numbers of PBMC and splenocytes (>1 x 10(8)) with bone marrow cells from the presensitized pigs failed to induce detectable GVHD or long-term chimerism in mice that were treated with depleting anti-T-cell and natural killer cell antibodies, cobra venom factor, medronate-liposomes, and 4 Gy of whole-body and 7 Gy of thymic irradiation. Histologic analysis revealed no mononuclear cell infiltration or GVHD-associated lesions in the liver, intestine, lungs, or skin of the mouse recipients. Furthermore, the recipient mice had no detectable T cells or anti-pig immunoglobulin G antibodies in the blood by 6 weeks after injection of porcine cells.

CONCLUSION

These results demonstrate that porcine T-cell function is severely impaired in the xenogeneic murine microenvironment.

Immunobiology of acute graft-versus-host disease

Graft-versus-host disease (GVHD) has been the primary limitation to the wider application of allogeneic bone marrow transplantation (BMT). The immunobiology of acute GVHD is complex and can be conceptualized to be a three-step process. In step 1, the conditioning regimen (irradiation and/or chemotherapy) leads to the damage and activation of host tissues and induces the secretion of inflammatory cytokines TNF-alpha and IL-1. As a consequence expression of MHC antigens and adhesion molecules is increased, thus enhancing the recognition of host alloantigens by donor T cells. Donor T-cell activation in step 2 is characterized by donor T-cell interaction with host APCs and subsequent proliferation, differentiation, and secretion of cytokines. Cytokines such as IL-2 and IFN-gamma enhance T-cell expansion, induce cytotoxic T cells (CTL) and natural killer (NK) cell responses, and prime additional mononuclear phagocytes to produce TNF-alpha and IL-1. These inflammatory cytokines in turn stimulate production of inflammatory chemokines, thus recruiting effector cells into target organs. In step 3, effector functions of mononuclear phagocytes are triggered via a secondary signal provided by lipopolysaccharide (LPS) that leaks through the intestinal mucosa damaged during step 1. This mechanism may result in the amplification of local tissue injury and further promotion of an inflammatory response, which, together with the CTL and NK components, leads to target tissue destruction in the transplant host.

Differential Roles for CCR5 Expression on Donor T Cells during Graft-versus-Host Disease Based on Pretransplant Conditioning

The coordinated expression of chemokines and receptors may be important in the directed migration of alloreactive T cells during graft-vs-host disease (GVHD). Recent work demonstrated in a murine model that transfer of CCR5-deficient (CCR5(-/-)) donor cells to nonconditioned haploidentical recipients resulted in reduced donor cell infiltration in liver and lymphoid tissues compared with transfer of CCR5(+/+) cells. To investigate the function of CCR5 during GVHD in conditioned transplant recipients, we transferred CCR5(-/-) or wild-type C57BL/6 (B6) T cells to lethally irradiated B6D2 recipients. Unexpectedly, we found an earlier time to onset and a worsening of GVHD using CCR5(-/-) T cells, which was associated with significant increases in the accumulation of alloreactive CD4(+) and CD8(+) T cells in liver and lung. Conversely, the transfer of CCR5(-/-) donor cells to nonirradiated recipients led to reduced infiltration of target organs, confirming previous studies and demonstrating that the role of CCR5 on donor T cells is dependent on conditioning of recipients. Expression of proinflammatory chemokines in target tissues was dependent on conditioning of recipients, such that CXCL10 and CXCL11 were most highly expressed in tissues of irradiated recipients during the first week post-transplant. CCR5(-/-) T cells were shown to have enhanced migration to CXCL10, and blocking this ligand in vivo improved survival in irradiated recipients receiving CCR5(-/-) T cells. Our data indicate that the effects of inhibiting CCR5/ligand interaction on donor T cells during GVHD differ depending on conditioning of recipients, a finding with potentially important clinical significance.

Pathophysiology of acute graft-versus-host disease

Graft-versus-host disease (GVHD) has been the primary limitation to the wider application of allogeneic bone marrow transplantation (BMT). The pathophysiology of acute GVHD is complex and can be conceptualized to be a three-step process based on murine studies. In step 1, the conditioning regimen leads to the damage and activation of host tissues and induces the secretion of inflammatory cytokines. As a consequence, the expression of MHC antigens and adhesion molecules is increased enhancing the recognition of host alloantigens by donor T cells. Donor T-cell activation in step 2 is characterized by donor T cell interaction with host APCs and subsequent proliferation, differentiation and secretion of cytokines. Cytokines such as IL-2 and IFN-gamma enhance T-cell expansion, induce cytotoxic T cells (CTL) and natural killer (NK) cell responses and prime additional mononuclear phagocytes to produce TNF-alpha and IL-1. These inflammatory cytokines in turn stimulate production of inflammatory chemokines, thus recruiting effector cells into target organs. In step 3, effector functions of mononuclear phagocytes are triggered via a secondary signal provided by lipopolysaccharide (LPS) that leaks through the intestinal mucosa damaged during step 1. This mechanism may result in the amplification of local tissue injury and further promotion of an inflammatory response, which, together with the CTL and NK components, leads to target tissue destruction in the transplant host. The following review discusses the three-step process of the pathophysiology of experimental acute GVHD.

CC Chemokine Receptor 2 Expression in Donor Cells Serves an Essential Role in Graft-versus-Host-Disease

The complete repertoire of cellular and molecular determinants that influence graft-vs-host disease (GVHD) is not known. Using a well-established murine model of GVHD (B6-->bm12 mice), we sought to elucidate the role of the donor non-T cell compartment and molecular determinants therein in the pathogenesis of GVHD. In this model the acute GVHD-inducing effects of purified B6 wild-type (wt) CD4(+) T cells was inhibited by wt non-T cells in a dose-dependent manner. Paradoxically, unlike the chronic GVHD phenotype observed in bm12 mice transplanted with B6wt unfractionated splenocytes, bm12 recipients of B6ccr2-null unfractionated splenocytes developed acute GVHD and died of IFN-gamma-mediated bone marrow aplasia. This switch from chronic to acute GVHD was associated with increased target organ infiltration of activated CD4(+) T cells as well as enhanced expression of Th1/Th2 cytokines, chemokines, and the antiapoptotic factor bfl1. In vitro, ccr2(-/-) CD4(+) T cells in unfractionated splenocytes underwent significantly less activation-induced cell death than B6wt CD4(+) T cells, providing another potential mechanistic basis along with enhanced expression of bfl1 for the increased numbers of activated T cells in target organs of B6ccr2(-/-) splenocyte-->bm12 mice. Collectively, these findings have important clinical implications, as they implicate the donor non-T cell compartment as a critical regulator of GVHD and suggest that ccr2 expression in this cellular compartment may be an important molecular determinant of activation-induced cell death and GVHD pathogenesis.

Acceleration of idiopathic pneumonia syndrome (IPS) in the absence of donor MIP-1 alpha (CCL3) after allogeneic BMT in mice

Idiopathic pneumonia syndrome (IPS) is a significant cause of morbidity and mortality after bone marrow transplantation (BMT) in humans. We developed a murine IPS model in which lethal pre-BMT conditioning and allogeneic T cells results in the recruitment of host monocytes and then donor T cells into the lung by day 7 after BMT, concomitant with development of severe lung dysfunction. We reported the T cell-dependent production of the T cell-attracting chemokine macrophage inflammatory protein-1 alpha (MIP-1 alpha) in the lungs of such recipient mice. We reasoned that MIP-1 alpha might be a critical mediator of IPS. Lethally conditioned mice received transplants of major histocompatibility complex-disparate marrow and either wild-type (MIP-1 alpha(+/+)) or knockout (MIP-1 alpha(-/-)) spleen cells. Recipients of MIP-1 alpha(-/-) cells exhibited accelerated mortality and a decrease in specific compliance that appeared earlier than in recipients of MIP-1 alpha(+/+) cells. Donor CD4(+) and CD8(+) T cell expansion was increased in the spleens of recipients of MIP-1 alpha(-/-) cells. Lungs of recipients of MIP-1 alpha(-/-) cells had earlier recruitment of both T-cell subsets by day 3 after BMT, concomitant with the influx of cells expressing the cytolysins granzymes A and B. Monocyte recruitment was not altered. Levels of inflammatory cytokines were not increased and levels of T cell-attracting chemokines were decreased. The level of the anti-inflammatory cytokine interleukin 13 (IL-13) was lower in the serum and lungs of recipients of MIP-1 alpha(-/-) cells, indicating a skewing toward a more inflammatory T helper cell type 1 (Th1) cytokine milieu. Donor-derived MIP-1 alpha may play a role in allogeneic-induced IPS by limiting aggressive expansion of CD4(+) and CD8(+) T cells.

Cytokine and chemokine profiles in autologous graft-versus-host disease (GVHD): interleukin 10 and interferon gamma may be critical mediators for the development of autologous GVHD

Administration of the immunosuppressive drug cyclosporine A (CsA) following autologous stem cell transplantation paradoxically elicits a systemic autoimmune syndrome resembling graft-versus-host disease (GVHD). This syndrome, termed autologous GVHD, is associated with autoreactive CD8(+) T cells that recognize major histocompatibility complex (MHC) class II determinants in association with a peptide from the invariant chain. To investigate the potential role of cytokines and chemokines in autologous GVHD, interleukin 2 (IL-2), IL-4, IL-10, interferon gamma (IFN-gamma), and macrophage inflammatory protein-1alpha (MIP-1alpha) gene expression in peripheral blood mononuclear cells (PBMCs) was determined in 36 patients treated with CsA following transplantation and correlated with the induction of cytolytic activity against autologous phytohemagglutinin-stimulated lymphocytes (PHA-blasts) and the breast cancer cell line (T47D). The determination of gene expression by real-time polymerase chain reaction (PCR) revealed that IL-10 mRNA levels by PBMCs in patients with autologous GVHD were 29-fold higher than in healthy individuals. IFN-gamma (4-fold), IL-2 (3-fold), and MIP-1alpha (44-fold) mRNA levels were also increased in GVHD-induced patients compared with healthy individuals. The ability of PBMCs to lyse autologous PHA-blasts and T47D tumor cells exhibited an identical temporal relationship with expression of IL-10 and IFN-gamma during autologous GVHD. Moreover, the susceptibility to autologous GVHD as assessed in 75 patients was significantly associated with the IL-10(-1082) G/G polymorphic alleles, allelic variants in the promoter region that govern IL-10 production. These findings indicate that IL-10 may play an unexpected but critical role in autologous GVHD and could be utilized to enhance a graft-versus-tumor effect after transplantation. Interestingly, polymorphisms in the IL-10 promoter region may also explain differences in the susceptibility of patients to autologous GVHD induction.

Transfection of macrophage inflammatory protein 1 alpha into B16 F10 melanoma cells inhibits growth of pulmonary metastases but not subcutaneous tumors

Macrophage inflammatory protein 1 alpha (MIP-1 alpha), a CC chemokine, is a chemoattractant for T cells and immature dendritic cells. Plasmacytoma cells expressing MIP-1 alpha generate a cytotoxic T cell response without affecting tumor growth. To understand this discrepancy, we compared a local tumor model with a metastatic one using MIP-1 alpha-transfected B16 F10 melanoma cells. Clonal idiosyncrasies were controlled by selecting three lipotransfected tumor clones and two pcDNA vector transfected control clones with equivalent in vitro proliferative capacities. No significant differences were seen between the MIP-1 alpha-producing and control melanoma cells after s.c. injection in the hind leg. All animals had a leg diameter of 10 cm in 18.5-21.5 days. However, after i.v. injection the number of pulmonary foci was significantly reduced in the MIP-1 alpha-producing clones. Injection of 10(6) control transfected cells resulted in a median of 98.5 tumor foci in 2 wk, whereas the injection of the MIP-1 alpha-producing clones resulted in 89.5, 26.5, and 0 foci. The number of metastatic foci was inversely proportional to the amount of MIP-1 alpha produced by the clone in vitro. Flow cytometry showed a significant increase in CD8(+) cells in lungs of mice with MIP-1 alpha-transfected tumors 3 days after injection. This increase was not maintained 10 days later despite continued production of MIP-1 alpha. The protection offered by transfection with MIP-1 alpha was significantly impaired in beta(2)-microglobulin(-/-) mice. Our findings suggest that MIP-1 alpha is effective in preventing the initiation of metastasis, but not at sustaining an effective antitumor response.

Absence of macrophage-inflammatory protein-1alpha delays central nervous system demyelination in the presence of an intact blood-brain barrier

Chemokines are small chemotactic cytokines that modulate leukocyte recruitment and activation during inflammation. Here, we describe the role of macrophage inflammatory protein-1alpha (MIP-1alpha) during cuprizone intoxication, a model where demyelination of the CNS features a large accumulation of microglia/macrophage without T cell involvement or blood-brain barrier disruption. RNase protection assays showed that mRNA for numerous chemokines were up-regulated during cuprizone treatment in wild-type, C57BL/6 mice. RANTES, inflammatory protein-10, and monocyte chemoattractant protein-1 showed greatest expression with initiation of insult at 1-2 wk of treatment, whereas MIP-1alpha and beta increased later at 4-5 wk, coincident with peak demyelination and cellular accumulation. The function of MIP-1alpha during demyelination was tested in vivo by exposing MIP-1alpha knockout mice (MIP-1alpha(-/-)) to cuprizone and comparing pathology to wild-type mice. Demyelination at 3.5 wk of treatment was significantly decreased in MIP-1alpha(-/-) mice ( approximately 36% reduction), a result confirmed by morphology at the electron microscopic level. The delay in demyelination was correlated to apparent decreases in microglia/macrophage and astrocyte accumulation and in TNF-alpha protein levels. It was possible that larger effects of the MIP-1alpha deficiency were being masked by other redundant chemokines. Indeed, RNase protection assays revealed increased expression of several chemokine transcripts in both untreated and cuprizone-treated MIP-1alpha(-/-) mice. Nonetheless, despite this possible compensation, our studies show the importance of MIP-1alpha in demyelination in the CNS and highlight its effect, particularly on cellular recruitment and cytokine regulation.

Bone marrow cell graft engineering: from bench to bedside

Bone marrow transplantation (BMT) has the potential to treat hemoglobinopathies (sickle cell and thalassemia) autoimmunity (diabetes, lupus, multiple sclerosis, rheumatoid arthritis, Crohn's colitis) and enzyme deficiency states. Graft versus host disease (GVHD) is a major complication and limitation to the therapeutic application of BMT. There have been many clinical trials and experimental animal models that have attempted to control GVHD through the engineering of the donor bone marrow cells (BMC). Historically, several methods have demonstrated effectiveness in controlling GVHD; however they were also associated with a marked increase in the rate of graft failure. Highly purified hematopoietic stem cells (HSC) engraft quite readily in genetically-matched recipients while they do not engraft as easily in MHC-disparate recipients. The numbers of HSC must be increased 100-200 fold in order to overcome the allogeneic barrier. We were the first to phenotypically and to functionally characterize a novel cell in the bone marrow that enables engraftment of highly purified HSC in allogeneic recipients. The discovery of graft facilitating cell populations has resulted in the restoration of the engraftment-potential of purified HSC between genetically-disparate individuals. The addition of facilitating cells (FC) to T cell-depleted BMC grafts results in allogeneic engraftment without GVHD or graft failure. New strategies of BMC engineering that retain FC and HSC but avoid GVHD have allowed successful engraftment in mismatched and older recipients. These techniques have expanded the therapeutic potential of BMT to virtually every candidate as well as to non-malignant diseases in which the morbidity associated with conventional BMT could not be accepted. This article reviews the transition of the FC technology from bench to bedside and discuss the potentially broad-reaching applications of BMT and mixed chimerism.

T-lymphocyte production of macrophage inflammatory protein-1α is critical to the recruitment of CD8+ T cells to the liver, lung, and spleen during graft-versus-host disease

To investigate the mechanism by which macrophage inflammatory protein-1α (MIP-1α) affects graft-versus-host disease (GVHD), the expression and function of MIP-1α in 2 murine models of GVHD were evaluated. In irradiated class I and class II disparate recipients, the expression of messenger RNA (mRNA) and protein for MIP-1α was significantly increased in GVHD target organs after transfer of allogeneic lymphocytes compared to syngeneic lymphocytes. When lymphocytes unable to make MIP-1α were transferred, there was a decrease in the production of MIP-1α in the liver, lung, and spleen of bm1 (B6.C-H2bm1/By) and bm12 (B6.C-H2bm12/KhEg) recipients compared to the transfer of wild-type splenocytes. At day 6 there was a 4-fold decrease in the number of transferred CD8+ T cells in the lung and approximately a 2-fold decrease in the number of CD8+ T cells in the liver and spleen in bm1 recipients after transfer of MIP-1α–deficient (MIP-1α−/−) splenocytes compared to wild-type (MIP-1α+/+) splenocytes. These differences persisted for 13 days after splenocyte transfer. In contrast, the number of donor CD4+ T cells found in the liver and lung was significantly increased after the transfer of MIP-1α−/− compared to wild-type splenocytes in bm12 recipients from day 6 through day 10. Thus, the transfer of allogeneic T cells was associated with the enhanced expression of MIP-1α in both a class I and class II mismatch setting. However, the increased expression only led to enhanced recruitment of CD8+, but not CD4+, donor T cells. Production of MIP-1α by donor T cells is important in the occurrence of GVHD and functions in a tissue-dependent fashion.

Induction of monocyte– and T-cell–attracting chemokines in the lung during the generation of idiopathic pneumonia syndrome following allogeneic murine bone marrow transplantation

Idiopathic pneumonia syndrome (IPS) is a significant complication following bone marrow transplantation (BMT). We have developed a murine model in which severe IPS is induced by pre-BMT conditioning and allogeneic T cells and is characterized by the recruitment of host monocytes and donor T cells into the lung by day 7 post-BMT. Chemokines regulate cellular recruitment and the migration of cells into inflammatory lesions. In this study, we examined the profiles of chemokines produced locally in the lung (parenchyma and bronchoalveolar lavage fluid) and systemically (serum) during the generation of IPS in the peri-BMT period. Protein and messenger RNA (mRNA) levels of CC chemokines (monocyte/lymphocyte attractants), especially monocyte chemoattractant protein (MCP)-1, macrophage inflammatory protein (MIP)-1, RANTES (regulated upon activation normal T-cell expressed and secreted), and C10, were preferentially induced in the lung by day 7 postallogeneic BMT. In addition, there was an increase in mRNA for IP-10 (a monocyte and Th1-cell chemoattractant). The CXC chemokines MIP-2 and KC, known neutrophil attractants, were moderately elevated. For the most part, these increases in chemokines were dependent on the coinfusion of allogeneic T cells with the BM inoculum. Ribonuclease protection assay and in situ hybridization analyses post-BMT showed that the lung was a major producer of MCP-1, a potent inducer of monocyte chemotaxis. Increases in MCP-1 levels in the lung preceded host APC influx whereas MIP-1 levels accompanied donor T-cell infiltration. In summary, we have shown that monocyte- and T-cell–attracting chemokines are associated with monocyte and T-cell recruitment during IPS.

Induction of monocyte– and T-cell–attracting chemokines in the lung during the generation of idiopathic pneumonia syndrome following allogeneic murine bone marrow transplantation

Idiopathic pneumonia syndrome (IPS) is a significant complication following bone marrow transplantation (BMT). We have developed a murine model in which severe IPS is induced by pre-BMT conditioning and allogeneic T cells and is characterized by the recruitment of host monocytes and donor T cells into the lung by day 7 post-BMT. Chemokines regulate cellular recruitment and the migration of cells into inflammatory lesions. In this study, we examined the profiles of chemokines produced locally in the lung (parenchyma and bronchoalveolar lavage fluid) and systemically (serum) during the generation of IPS in the peri-BMT period. Protein and messenger RNA (mRNA) levels of CC chemokines (monocyte/lymphocyte attractants), especially monocyte chemoattractant protein (MCP)-1, macrophage inflammatory protein (MIP)-1, RANTES (regulated upon activation normal T-cell expressed and secreted), and C10, were preferentially induced in the lung by day 7 postallogeneic BMT. In addition, there was an increase in mRNA for IP-10 (a monocyte and Th1-cell chemoattractant). The CXC chemokines MIP-2 and KC, known neutrophil attractants, were moderately elevated. For the most part, these increases in chemokines were dependent on the coinfusion of allogeneic T cells with the BM inoculum. Ribonuclease protection assay and in situ hybridization analyses post-BMT showed that the lung was a major producer of MCP-1, a potent inducer of monocyte chemotaxis. Increases in MCP-1 levels in the lung preceded host APC influx whereas MIP-1 levels accompanied donor T-cell infiltration. In summary, we have shown that monocyte- and T-cell–attracting chemokines are associated with monocyte and T-cell recruitment during IPS.

New strategies for preventing graft-versus-host disease

Graft-versus-host disease (GVHD) is a complex condition that can occur after allogeneic bone marrow transplantation and remains a significant cause of morbidity. GVHD occurs when donor immunocompetent T cells react to and attack the genetically disparate host. The etiology of GVHD is complex, with numerous variables affecting its incidence and severity. Recent work has focused upon blunting the initial interactions between the donor T cell and the host. Because GVHD is linked with the beneficial graft-versus-tumor (GVT) effect that occurs after allogenic bone marrow transplantation, previous attempts to circumvent GVHD (i.e. by depletion of T cells from the donor graft) also resulted in increased relapse rates from the original tumor. The ideal scenario involves the tolerization or anergy of the donor T cell that attacks the host while allowing donor cells to mediate GVT effects. Recent work has attempted to address several pivotal features of GVHD: the variables that affect its induction and severity; the effector mechanisms; and whether GVHD can be suppressed yet GVT effects be maintained. Questions about these features need answers to enable us to design successful approaches for intervention.