Inflammatory Cytokine Networks in Gastrointestinal Tract Graft vs. Host Disease

Graft vs. host disease (GVHD) is the major non-relapse complication associated with allogeneic hematopoietic stem cell transplantation (HSCT). Damage to the gastrointestinal (GI) tract from acute GVHD is a particularly serious event that can result in significant morbidity and mortality. Proinflammatory cytokines play a critical role in the pathophysiology of intestinal GVHD, in part by activating donor T cell populations which subsequently induce tissue damage. In this review, we summarize pre-clinical data derived from experimental murine models that have examined the role of inflammatory cytokine pathways that play critical roles in the pathophysiology of GVHD of the GI tract. Specific areas of focus are on STAT 3-dependent cytokines (e.g., IL-6, IL-23, and IL-21), and members of the IL-1 cytokine family, both of which have been shown to induce pathological damage within the GI tract during this disease. We also review established and ongoing efforts to translate these pre-clinical findings into the clinic in an effort to reduce morbidity and mortality due to this complication

Successful unrelated marrow transplantation for patients over the age of 40 with chronic myelogenous leukemia

AbstractSome older patients (> or =40 years) with chronic myelogenous leukemia (CML) who lack human leukocyte antigen (HLA)-identical sibling donors are not offered unrelated marrow transplantation because of concerns over excessive regimen-related toxicity, in particular due to graft-vs.-host disease (GVHD). The purpose of this study was to determine the efficacy and toxicity of unrelated marrow transplantation in older CML patients using a regimen designed to minimize the severity of GVHD. Thirty-one consecutive patients over the age of 40 with CML received unrelated marrow transplants between January 1988 and June 1997. Twenty-one patients were transplanted in chronic phase while ten were transplanted in the accelerated phase of their disease. Fifteen patients received transplants from phenotypically matched donors while 16 received marrow grafts from donors who were mismatched at one HLA locus. GVHD prophylaxis consisted of ex vivo T cell depletion of the donor marrow graft plus posttransplant cyclosporine administration. Durable engraftment was achieved in 29 of 31 patients (94%). The probability of developing grades II-IV or severe grades III-IV acute GVHD was 39.2 and 7.1%, respectively. There was no difference in the incidence of grades II-IV acute GVHD between patients transplanted with marrow grafts from phenotypically matched (38.1%) vs. those transplanted from mismatched unrelated donors (40%, p = 0.99). The 2-year probability of relapse for the entire population was 29.4%. Relapse was significantly higher for patients transplanted in accelerated phase (60%) than for those in chronic phase (13.8%, p = 0.027). The 2-year probability of overall survival and disease-free survival for the entire cohort was 56 and 45%, respectively. There was no significant difference in survival or disease-free survival for patients receiving phenotypically matched vs. mismatched marrow grafts. Immunological reconstitution for this cohort was compared with a younger (<40 years) patient population that had been similarly transplanted over the same time period. Immune function as assessed by total T cell, B cell, NK cell, and T cell subset reconstitution posttransplant was quantitatively equivalent in the two groups with most parameters normalizing within 18 months of transplant. We conclude that CML patients over the age of 40 who have either phenotypically matched or one antigen-mismatched unrelated donors can successfully undergo allogeneic marrow transplantation. T cell depletion of the marrow graft may be advantageous in these older patients by reducing GVHD severity, particularly in those patients transplanted with HLA-disparate marrow grafts.Biol Blood Marrow Transplant 1998;4(1):3-12

Development of a sensitive, highly controlled assay for molecular detection of the Philadelphia chromosome in patients with chronic myelogenous leukemia

The Philadelphia chromosome (Ph1), present in [ges]95% of chronic myelogenous leukemia (CML) patients, is a well-characterized translocation that results in a unique chimeric gene product (BCR/ABL) with transforming capability. Molecular methods utilizing the polymerase chain reaction (PCR) to detect BCR/ABL mRNA transcripts has been useful for detecting minimal residual disease (MRD) after treatment, as well as for establishing the diagnosis of CML. Amplification-based assays for the BCR/ABL transcript, however, have shown variable reproducibility and sensitivity. This variability may be largely due to technical differences and insufficient controls. In this report, we describe the development of a highly controlled, reproducible, and sensitive PCR assay to detect Ph1 that is well suited to clinical and research applications. A validation study of 82 samples was performed consisting of 25 dilutions of K562 cells (Ph1+) into normal cultured B cells, 26 pre- and post-transplant peripheral blood samples from CML patients, 16 peripheral blood samples for diagnosis of CML, and 15 peripheral blood samples from healthy individuals. RNA isolated from 3 to 5 million leukocytes was reverse transcribed (RT) and amplified by nested primer PCR. The products were characterized using agarose gel electrophoresis. Approximately 1000 Ph1-positive cells admixed with 106 normal cells were detectable after one round of amplification. In 60% of assays where one Ph1-positive cell was admixed with 106 normal cells, a BCR/ABL product was detectable after nested primer PCR. Specific measures to ensure accurate results in routine testing included (a) assessing RNA integrity and adequate cDNA preparation by detection of the constitutively expressed ABL mRNA, (b) monitoring sensitivity with the addition and detection of K562 RNA mixed with RNA from unknown samples (failure to detect the "spiked" K562 RNA indicates the presence of inhibitors or ribonucleases within the unknown RNA sample), (c) detection of nucleic acid contaminants by using negative controls in every assay, and (d) duplicate analysis of all samples and controls. Internally, this assay was 100% reproducible. Our results verify that nested primer RT-PCR is a fast, sensitive alternative to cytogenetic or Southern blot analysis for monitoring MRD after treatment and for diagnosis of CML. In addition, the highly controlled detection scheme presented here can be used as a general model for the development of other amplification-based detection assays.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/31883/1/0000835.pd

Antiviral Responses following L-Leucyl-L-Leucine Methyl Esther (LLME)-Treated Lymphocyte Infusions: Graft-versus-Infection without Graft-versus-Host Disease

Although allogeneic hematopoietic progenitor cell transplant (HPCT) is curative therapy for many disorders, it is associated with significant morbidity and mortality, which can be related to graft-versus-host disease (GVHD) and the immunosuppressive measures required for its prevention and/or treatment. Whether the immunosuppression is pharmacologic or secondary to graft manipulation, the graft recipient is left at increased risk of the threatening opportunistic infection. Refractory viral diseases in the immunocompromised host have been treated by infusion of virus-specific lymphotyces and by unmanipulated donor lymphocyte infusion (DLI) therapy. L-leucyl-L-leucine methyl ester (LLME) is a compound that induces programmed cell death of natural killer (NK) cells, monocytes, granulocytes, most CD8+ T cells, and a small fraction of CD4+ T cells. We have undertaken a study of the use of LLME-treated DLI following T cell-depleted allogeneic HPCT, specifically to aid with immune reconstitution. In this ongoing clinical trial, we have demonstrated the rapid emergence of virus-specific responses following LLME DLI with minimal associated GVHD. This paper examines the pace of immune recovery and the rapid development of antiviral responses in 6 patients who developed viral infections during the time period immediately preceding or coincident with the administration of the LLME DLI

A colitogenic memory CD4+ T cell population mediates gastrointestinal graft-versus-host disease

Damage to the gastrointestinal tract is a major cause of morbidity and mortality in graft-versus-host disease (GVHD) and is attributable to T cell–mediated inflammation. In this work, we identified a unique CD4+ T cell population that constitutively expresses the β2 integrin CD11c and displays a biased central memory phenotype and memory T cell transcriptional profile, innate-like properties, and increased expression of the gut-homing molecules α4β7 and CCR9. Using several complementary murine GVHD models, we determined that adoptive transfer and early accumulation of β2 integrin–expressing CD4+ T cells in the gastrointestinal tract initiated Th1-mediated proinflammatory cytokine production, augmented pathological damage in the colon, and increased mortality. The pathogenic effect of this CD4+ T cell population critically depended on coexpression of the IL-23 receptor, which was required for maximal inflammatory effects. Non–Foxp3-expressing CD4+ T cells produced IL-10, which regulated colonic inflammation and attenuated lethality in the absence of functional CD4+Foxp3+ T cells. Thus, the coordinate expression of CD11c and the IL-23 receptor defines an IL-10–regulated, colitogenic memory CD4+ T cell subset that is poised to initiate inflammation when there is loss of tolerance and breakdown of mucosal barriers

Chapter 35: Immune Reconstitution and Tolerance

peer reviewedHematopoietic cell transplantation (HCT) remains the only curative treatment option for many patients with hematological malignancies and genetic disorders. Recipients can receive either an autologous or allogeneic graft, which is often dependent upon the primary disease for which transplantation is contemplated. One of the major goals of transplantation is the development of a fully functional immune system. Patients undergoing allogeneic hematopoietic cell transplantation (alloHCT), in particular, have the highest rate of transplantrelated mortality (TRM) due to complications that can result from immunodeficiencies or immune dysregulation that occurs as a consequence of the procedure. These include, but are not limited to, infections, graft‐versus‐host disease (GvHD), autoimmune disorders, and secondary malignancies. Recovery of a fully functional immune system is thus critical for HCT success and improving immune reconstitution is of great clinical interest. This chapter will focus on immune reconstitution following allo‐HCT since immune recovery is more complicated in this setting due to the underlying HLA disparity between the donor and the recipient

Graft-facilitating doses of ex vivo activated gammadelta T cells do not cause lethal murine graft-vs.-host disease

AbstractThe purpose of this study was to examine the ability of gamma(delta) T cells to cause graft-vs.-host disease (GVHD) after allogeneic bone marrow transplantation (BMT) and to determine whether these cells offered any therapeutic advantages relative to alphabeta T cells. Due to the paucity of naive gamma(delta) T cells in mice and humans, gamma(delta), T cells (obtained from alpha(beta) T cell-deficient murine donors) were ex vivo activated and expanded in interleukin (IL)-2 so as to achieve sufficient cell numbers and to serve as a more clinically feasible strategy. After transplantation into lethally irradiated hosts, donor gamma(delta) T cells were detected in target organs of GVHD such as the spleen and intestines 2 weeks after BMT and constituted the primary T cell subpopulation. Large doses (150 x 10(6)) of activated gamma(delta) T cells, which we have previously shown capable of facilitating engraftment in MHC-disparate recipients, failed to cause fatal GVHD in lethally irradiated recipients of MHC-incompatible donor marrow grafts (C57BL/6 [H-2b]-->B10.BR [H-2k] and C57BL/6 [H-2b]-B6D2F1[H-2b/d]). The absence of GVHD was confirmed by histologic analysis of target organs, splenic B cell reconstitution, and appropriate negative selection in the thymus, that were all comparable to those observed in mice transplanted with T cell-depleted BM only. While early splenic reconstitution was attributable to donor gamma(delta) T cells, analysis of durably engrafted chimeras 2 months posttransplant revealed that the vast majority of donor splenic T cells expressed the alpha(beta) T cell receptor. The results of secondary adoptive transfer assays showed that these cells were tolerant of recipient alloantigens in vivo, demonstrating that gamma(delta) T cells did not prevent the subsequent development of donor anti-host tolerance in BM-derived alpha(beta) T cells. When comparatively evaluated, the minimal number of naive alpha(beta) T cells necessary for donor engraftment caused significantly more fatal GVHD than the corresponding minimal dose of activated gamma(delta) T cells and thus had a superior therapeutic index. These studies indicate that doses of activated gamma(delta) T cells that are able to promote alloengraftment do not cause lethal GVHD in mice transplanted with MHC-incompatible marrow grafts.Biol Blood Marrow Transplant 1999;5(4):222-30