The Impact of Inflammation on the Immune Responses to Transplantation: Tolerance or Rejection?

Transplantation (Tx) remains the optimal therapy for end-stage disease (ESD) of various solid organs. Although alloimmune events remain the leading cause of long-term allograft loss, many patients develop innate and adaptive immune responses leading to graft tolerance. The focus of this review is to provide an overview of selected aspects of the effects of inflammation on this delicate balance following solid organ transplantation. Initially, we discuss the inflammatory mediators detectable in an ESD patient. Then, the specific inflammatory mediators found post-Tx are elucidated. We examine the reciprocal relationship between donor-derived passenger leukocytes (PLs) and those of the recipient, with additional emphasis on extracellular vesicles, specifically exosomes, and we examine their role in determining the balance between tolerance and rejection. The concept of recipient antigen-presenting cell "cross-dressing" by donor exosomes is detailed. Immunological consequences of the changes undergone by cell surface antigens, including HLA molecules in donor and host immune cells activated by proinflammatory cytokines, are examined. Inflammation-mediated donor endothelial cell (EC) activation is discussed along with the effect of donor-recipient EC chimerism. Finally, as an example of a specific inflammatory mediator, a detailed analysis is provided on the dynamic role of Interleukin-6 (IL-6) and its receptor post-Tx, especially given the potential for therapeutic interdiction of this axis with monoclonal antibodies. We aim to provide a holistic as well as a reductionist perspective of the inflammation-impacted immune events that precede and follow Tx. The objective is to differentiate tolerogenic inflammation from that enhancing rejection, for potential therapeutic modifications. (Words 247).

Chimerism, the Microenvironment and Control of Leukemia

Transplantation of allogeneic hematopoietic cells faces two barriers: failure of engraftment due to a host versus graft reaction, and the attack of donor cells against the patient, the graft versus host (GVH) reaction. This reaction may lead to GVH disease (GVHD), but in patients transplanted due to leukemia or other malignant disorders, this may also convey the benefit of a graft versus leukemia (GVL) effect. The interplay of transplant conditioning with donor and host cells and the environment in the patient is complex. The microbiome, particularly in the intestinal tract, profoundly affects these interactions, directly and via soluble mediators, which also reach other host organs. The microenvironment is further altered by the modifying effect of malignant cells on marrow niches, favoring the propagation of the malignant cells. The development of stable mixed donor/host chimerism has the potential of GVHD prevention without necessarily increasing the risk of relapse. There has been remarkable progress with novel conditioning regimens and selective T-cell manipulation aimed at securing engraftment while preventing GVHD without ablating the GVL effect. Interventions to alter the microenvironment and change the composition of the microbiome and its metabolic products may modify graft/host interactions, thereby further reducing GVHD, while enhancing the GVL effect. The result should be improved transplant outcome.

Allogeneic Human Double Negative T Cells as a Novel Immunotherapy for Acute Myeloid Leukemia and Its Underlying Mechanisms

Purpose: To explore the potential of ex vivo expanded healthy donor-derived allogeneic CD4 and CD8 double-negative cells (DNT) as a novel cellular immunotherapy for leukemia patients.Experimental Design: Clinical-grade DNTs from peripheral blood of healthy donors were expanded and their antileukemic activity and safety were examined using flow cytometry-based in vitro killing assays and xenograft models against AML patient blasts and healthy donor-derived hematopoietic cells. Mechanism of action was investigated using antibody-mediated blocking assays and recombinant protein treatment assays.Results: Expanded DNTs from healthy donors target a majority (36/46) of primary AML cells, including 9 chemotherapy-resistant patient samples in vitro, and significantly reduce the leukemia load in patient-derived xenograft models in a DNT donor-unrestricted manner. Importantly, allogeneic DNTs do not attack normal hematopoietic cells or affect hematopoietic stem/progenitor cell engraftment and differentiation, or cause xenogeneic GVHD in recipients. Mechanistically, DNTs express high levels of NKG2D and DNAM-1 that bind to cognate ligands preferentially expressed on AML cells. Upon recognition of AML cells, DNTs rapidly release IFNγ, which further increases NKG2D and DNAM-1 ligands' expression on AML cells. IFNγ pretreatment enhances the susceptibility of AML cells to DNT-mediated cytotoxicity, including primary AML samples that are otherwise resistant to DNTs, and the effect of IFNγ treatment is abrogated by NKG2D and DNAM-1-blocking antibodies.Conclusions: This study supports healthy donor-derived allogeneic DNTs as a therapy to treat patients with chemotherapy-resistant AML and also reveals interrelated roles of NKG2D, DNAM-1, and IFNγ in selective targeting of AML by DNTs. Clin Cancer Res; 24(2); 370-82. ©2017 AACR.

[Th1/2-balance shift during acute graft-versus-host reaction developing against the background of experimental hyperlipidemia]

AIM

Evaluate the effect of experimental hyperlipidemia on the intensity of development of acute graft-versus-host reaction (GVHR) in mice.

MATERIALS AND METHODS

Half-allogenic system C57Bl/6 (C57Bl/6 x DBA/2)F1 was used as a laboratory model of acute GVHR. Experimental hyperlipidemia in mice-recipients was induced by repeated administration of poloxamer 407.

RESULTS

Lethality in the group of mice with acute GVHR developing against the background of preceding hyperlipidemia was significantly higher (70% at day 50 of GVHR development) compared with control group with acute GVHR (50% lethality at day 50). Such effect on the degree of severity of acute GVHR induced under the conditions of hyperlipidemia is confirmed by a more pronounced destruction of thymus in mice of the group with previously induced hyperlipidemia.

CONCLUSION

Preceding hyperlipidemia induced by administration of poloxamer 407 shifts Th1/2- balance in the development of acute GVHR towards Th1. Mechanisms of this effect and possible role of nuclear LXR receptors in regulation of immune reactions are discussed.

Development of insulin allergy after bone marrow transplantation

BACKGROUND

Insulin allergy is a not uncommon condition even though human insulin and insulin analogues are widely used. However, the development of insulin allergy after bone marrow transplantation has not been reported.

CASE REPORT

A 44-year-old Japanese woman had aplastic anaemia and secondary haemochromatosis. She was diagnosed with having diabetes at age 32 years and had been treated with human insulin. At age 34 years, bone marrow transplantation was performed. One year later, a rash and urticaria appeared immediately after insulin injections. Intracutaneous tests were positive for both human insulins and analogues, whereas the test for protamine was negative. Furthermore, an IgE-radioallergosorbent test against insulin was positive. Thus, we diagnosed the patient with having an IgE-mediated type I allergy against insulin. Insulin therapy with insulin aspart, which showed the least skin reaction, was continued and the insulin allergy disappeared in 7 years.

CONCLUSIONS

This is the first description of insulin allergy after bone marrow transplantation. Our case underscores the effects of bone marrow cells on IgE-mediated type I allergy for insulin.

Blockade of IL-6-signaling inhibits the pathogenesis of CD4+ T cell-mediated lethal graft-versus-host reaction against minor histocompatibility antigen

Graft-versus-host reaction (GVHR) is considered as a problem in hematopoietic cell transplantation. We found that CD45RB(high) CD62L(+) naïve CD4(+) T cells from wild-type B10D2 (H-2d MMTV6(-)) mice immediately differentiated into effector T cells producing high-levels of various cytokines after the transfer into BALB/c RAG2(-/-) (H-2d MMTV6(+)) mice. The expanded CD4(+) T cells, which have almost TCR Vβ3 chain, recognized the minor antigen of recipient mice and brought typical severe GVHR symptoms such as eyelid irritation, diarrhea, and liver failure. Eventually, all of the recipient mice transferred CD4(+) T cells was dead within 10 days. We demonstrated here that blockade of IL-6 signaling by administration of anti-IL-6 receptor (IL-6R) monoclonal antibody (mAb) remarkably inhibited the CD4(+) T cell-mediated lethal GVHR. In addition, we confirmed that the in vivo injection of anti-IL-6R mAb prevented the generation of effector CD4(+) T cells which produce the inflammatory cytokines such as IFN-γ, TNF-α, and IL-17. These findings indicated that IL-6 was a critical factor in the CD4(+) T cell-dependent acute GVHR induced by a minor-antigen, suggesting that IL-6-mediated signaling pathway would be a strong therapeutic target in T cell-mediated GVHR as well as other diseases including autoimmune and inflammation.

[Transplantation of the bone marrow from a HLA-compatible unrelated donor after immunoablative conditioning in children with acquired aplastic anemia unresponsive to combined immunosuppressive therapy: preliminary results]

AIM

To analyze the efficiency of transplantation of the bone marrow from a HLA-compatible unrelated donor and continued immunosuppressive therapy (IST) in children with aplastic anemia (AA) unresponsive to 2 courses of IST.

SUBJECTS AND METHODS

The study enrolled 14 children aged 2-16 years (median 9 years). A control group comprised 26 patients in whom IST was continued. The median interval between the diagnosis of AA and transplantation was 26 months (9-156 months). The conditioning regimen consisted of thoracoabdominal irradiation in a dose of 2 Gy, fludarabin (Flu) 100-150 mg/m2, cyclophosphamide (Cy) 100-200 mg/kg, antithymocyte globulin (ATG) in 11 patients and Flu, Cy, and ATG in 3. A graft-versus-host reaction was prevented with mycophenolate mefetil in all the patients, tacrolimus in 11, and cyclosporin A in 3. Donors were compatible for high-resolution typing of 10/10 and 9/10 alleles in 8 and 6 patients, respectively; the source of a transplant was bone marrow in 13 patients and granulocyte colony-stimulating factor-mobilized peripheral blood precursors in one case.

RESULTS

Thirteen patients achieved primary engraftment after single transplantation; one patient did after repeat transplantation. Grades I to II graft-versus-host reaction (GVHR) developed in 9 patients; postengraftment life-threatening infections in 3, extensive chronic GVHR in 2, circumscribed GVHR in 7. All fourteen hemopoietic cell transplant recipients followed for a median 17.5 months (range 1-71 months) were survivors.

CONCLUSION

The likelihood of good survival after unrelated transplantations in AA is much higher than that after continued IST: 100% versus 15 +/- 11%.

[Role of antithymocyte globulin in reducing the incidence of complications after allogeneic hemopoietic cell transplantation]

AIM

To evaluate the efficacy of antithymocyte globulin (ATG) used in conditioning modes before allogeneic hemopoietic cell transplantation (allo-HCT) and its effect in reducing the incidence of posttransplantation complications.

SUBJECTS AND METHODS

The study assessed the results of 92 allo-HCTs depending on the presence or absence of ATG in conditioning modes, the doses of Atgam (60 mg/kg or more), the presence or absence of acute leukemia (AL) in remission before HCT.

RESULTS

In patients with AL in remission receiving ATG in conditioning modes (Atgam 60 mg/kg or thymoglobulin 7.5 mg/kg), overall three-year survival was 60%. Increasing the dose of Atgam up to more than 60 mg/kg resulted in higher transplantation-associated mortality (TAM) rates than did with the Atgam dose of 60 mg/kg (p < 0.01).

CONCLUSION

Allo-HCT is the treatment of choice for patients with AL in the presence of an HLA-identical related or unrelated donor. The use of Atgam in a course dose of not more than 60 mg/kg or thymoglobulin 7.5 mg/kg in conditioning modes is associated with low TAM rates and higher overall survival in earlier-stage disease in complete clinical hematological remission as compared with those in patients with expanded-stage AL, rather than in AL in remission at the start of conditioning before HCT.

Partial HLA matching and RH incompatibility resulting in graft versus host reaction and Evans syndrome after liver transplantation

We report a case of a 67-year-old male who underwent OLT from a deceased, sex-matched donor. Two months later he developed Evans syndrome and GVHD of the skin. Donor and recipient were matched for HLA-A and -B loci in the direction of rejection but mismatched in the direction of GVHD and fully mismatched for DRB1. These mismatches were permissible for engraftment of donor T-cells but led to GVHD. Chimerism appeared restricted to the T-cell compartment. In this case, partially matched passenger lymphocytes triggered a graft versus host reaction. In addition, alloantibodies caused cytopenias that improved after immunosuppression. HLA typing was critical in confirming this rare diagnosis and elucidating its cause. Recipients of solid organs from donors that are partially matched in the direction of rejection may need to be closely monitored for GVHD.

Allogeneic memory T cell response

Recent data have revealed marked differences in alloresponses mediated by memory T cells during GVH and host-versus-graft (HVG) reactions (summarized in Table 1). Even though the mechanisms are not completely understood, it is clear that all memory T cells including nonallospecific, crossreactive, and allospecific memory T cells have decreased ability to induce GVHD. Selection of memory T cells or removal of naïve T cells will not only prevent GVHD, but could also enhance immune reconstitution, facilitate engraftment, and have the potential to enhance antitumor effects. A clinical trial has been planned. Successful translation of this approach in the clinic will improve the safety, enhance the effectiveness, and broaden the scope of allogeneic hematopoietic stem cell transplantation.

Adult human fibroblasts are potent immunoregulatory cells and functionally equivalent to mesenchymal stem cells

Bone marrow mesenchymal stem cells (MSC) have potent immunosuppressive properties and have been advocated for therapeutic use in humans. The nature of their suppressive capacity is poorly understood but is said to be a primitive stem cell function. Demonstration that adult stromal cells such as fibroblasts (Fb) can modulate T cells would have important implications for immunoregulation and cellular therapy. In this report, we show that dermal Fb inhibit allogeneic T cell activation by autologously derived cutaneous APCs and other stimulators. Fb mediate suppression through soluble factors, but this is critically dependent on IFN-gamma from activated T cells. IFN-gamma induces IDO in Fb, and accelerated tryptophan metabolism is at least partly responsible for suppression of T cell proliferation. T cell suppression is reversible, and transient exposure to Fb during activation reprograms T cells, increasing IL-4 and IL-10 secretion upon restimulation. Increased Th2 polarization by stromal cells is associated with amelioration of pathological changes in a human model of graft-vs-host disease. Dermal Fb are highly clonogenic in vitro, suggesting that Fb-mediated immunosuppression is not due to outgrowth of rare MSC, although dermal Fb remain difficult to distinguish from MSC by phenotype or transdifferentiation capacity. These results suggest that immunosuppression is a general property of stromal cells and that dermal Fb may provide an alternative and accessible source of cellular therapy.

Acute graft versus host disease

Acute graft-versus-host disease (GVHD) occurs after allogeneic hematopoietic stem cell transplant and is a reaction of donor immune cells against host tissues. Activated donor T cells damage host epithelial cells after an inflammatory cascade that begins with the preparative regimen. About 35%–50% of hematopoietic stem cell transplant (HSCT) recipients will develop acute GVHD. The exact risk is dependent on the stem cell source, age of the patient, conditioning, and GVHD prophylaxis used. Given the number of transplants performed, we can expect about 5500 patients/year to develop acute GVHD. Patients can have involvement of three organs: skin (rash/dermatitis), liver (hepatitis/jaundice), and gastrointestinal tract (abdominal pain/diarrhea). One or more organs may be involved. GVHD is a clinical diagnosis that may be supported with appropriate biopsies. The reason to pursue a tissue biopsy is to help differentiate from other diagnoses which may mimic GVHD, such as viral infection (hepatitis, colitis) or drug reaction (causing skin rash). Acute GVHD is staged and graded (grade 0-IV) by the number and extent of organ involvement. Patients with grade III/IV acute GVHD tend to have a poor outcome. Generally the patient is treated by optimizing their immunosuppression and adding methylprednisolone. About 50% of patients will have a solid response to methylprednisolone. If patients progress after 3 days or are not improved after 7 days, they will get salvage (second-line) immunosuppressive therapy for which there is currently no standard-of-care. Well-organized clinical trials are imperative to better define second-line therapies for this disease. Additional management issues are attention to wound infections in skin GVHD and fluid/nutrition management in gastrointestinal GVHD. About 50% of patients with acute GVHD will eventually have manifestations of chronic GVHD.

Graft-versus-host disease: a surge of developments

Stanley Riddell and Frederick Appelbaum review progress in preventing graft-versus-host disease following allogeneic hematopoietic cell transplantation for malignancies or other life-threatening blood diseases.

Absence of donor T-cell-derived soluble TNF decreases graft-versus-host disease without impairing graft-versus-tumor activity

Tumor necrosis factor (TNF) plays an important role in graft-versus-host disease (GVHD) and graft-versus-tumor (GVT) activity after allogeneic bone marrow transplantation (allo-BMT). TNF can be expressed in a membrane-bound form (memTNF) and as a soluble (solTNF) molecule after being cleaved by the TNF-alpha converting enzyme (TACE). To study the contribution of donor T-cell-derived memTNF versus solTNF in GVHD and GVT, we used mice containing a noncleavable allele in place of endogenous TNF (memTNF(Delta/Delta)) as donors in murine BMT models. Recipients of memTNF T cells developed significantly less GVHD than recipients of wild-type (wt) T cells. In contrast, GVT activity mediated by memTNF T cells remained intact, and alloreactive memTNF T cells showed no defects in proliferation, activation, and cytotoxicity. These data suggest that suppressing the secretion of solTNF by donor T cells significantly decreases GVHD without impairing GVT activity.

Host-derived Langerhans cells persist after MHC-matched allografting independent of donor T cells and critically influence the alloresponses mediated by donor lymphocyte infusions

Mouse models of minor histocompatibility Ag-mismatched bone marrow transplantation were used to study donor dendritic cell (DC) reconstitution after conditioning, variables influencing the persistence of residual host DCs in different compartments, their phenotype, and their role in governing donor lymphocyte infusion (DLI)-mediated alloresponses. Reconstitution of all splenic DC subsets occurred rapidly after bone marrow transplantation and before T cell reconstitution. However, in contrast to MHC-mismatched chimeras, residual host-derived DCs persisted in the cutaneous lymph nodes (CLNs) of MHC-matched chimeras despite the presence or addition of donor T cells to the graft. The phenotype of these residual host-derived DCs in CLNs was consistent with Langerhans' cells (LCs). We confirmed their skin origin and found near-complete preservation of host-derived LCs in the skin. Host-derived LCs retained their ability to continuously traffic to the CLNs, expressed homogeneously increased levels of costimulatory molecules, and could capture and carry epicutaneously applied Ags. To determine the role of residual host LCs in governing DLI-mediated alloresponses, we administered DLI alone or after topical application of the TLR7 ligand imiquimod, which is known to enhance the LC emigration from the skin. DLI administration resulted in a decrease in host-derived DCs in the CLNs and increased recruitment of donor-derived DCs to the skin, whereas imiquimod augmented their alloreactivity. These results suggest uniqueness of the MHC-matched setting in relation to the persistence of host-derived DCs in the skin and points to a previously unrecognized role of host-derived LCs in the induction of DLI-mediated graft-vs-host alloresponses.

Intervention of MAdCAM-1 or fractalkine alleviates graft-versus-host reaction associated intestinal injury while preserving graft-versus-tumor effects

Coincidence of the beneficial graft-vs.-tumor (GVT) effects and the detrimental graft-vs.-host disease (GVHD) remains the major obstacle against the widespread use of allogeneic bone marrow transplantation (BMT) as tumor immunotherapy. We here demonstrate that intervention of MAdCAM-1 (mucosal vascular addressin cell adhesion molecule-1) or fractalkine/CX3CL1 after the expansion of allo-reactive donor CD8 T cells selectively inhibits the recruitment of effector donor CD8 T cells to the intestine and alleviates the graft-vs.-host reaction (GVHR) associated intestinal injury without impairing GVT effects. In a nonirradiated acute GVHD model, donor CD8 T cells up-regulate the expression of intestinal homing receptor alpha4beta7 and chemokine receptors CXCR6 and CX3CR1, as they differentiate into effector cells and subsequently infiltrate into the intestine. Administration of anti-MAdCAM-1 antibody or anti-fractalkine antibody, even after the expansion of alloreactive donor CD8 T cells, selectively reduced the intestine-infiltrating donor CD8 T cells and the intestinal crypt cell apoptosis without affecting the induction of donor derived anti-host CTL or the infiltration of donor CD8 T cells in the hepatic tumor. Moreover, in a clinically relevant GVHD model with myeloablative conditioning, these antibodies significantly improved the survival and loss of weight without impairing the beneficial GVT effects. Thus, interruption of alpha4beta7-MAdCAM-1 or CX3CR1-fractalkine interactions in the late phase of GVHD would be a novel therapeutic approach for the separation of GVT effects from GVHR-associated intestinal injury.

Single-cell cloning of human, donor-derived antileukemia T-cell lines for in vitro separation of graft-versus-leukemia effect from graft-versus-host reaction

In previous studies, we showed the possibility of expanding in vitro polyclonal CTL lines directed against patient leukemia cells using effector cells derived from both HLA-matched and HLA-mismatched hematopoietic stem cell donors. Some CTL lines, especially those derived from an HLA-disparate donor, displayed residual alloreactivity against patient nonmalignant cells. In this study, we evaluated the possibility of separating in vitro CTLs with selective graft-versus-leukemia (GVL) activity from those potentially involved in the development of graft-versus-host disease (GVHD) through single T-cell cloning of antileukemia polyclonal CTL lines. We showed that CTLs that were expanded from a single T-cell clone (TCC), able to selectively kill leukemia blasts and devoid of alloreactivity towards nonmalignant cells, can be obtained from antileukemia alloreactive polyclonal CTL lines. TCCs expressed a wide repertoire of different T-cell receptor (TCR)-Vbeta families, mainly produced IFNgamma and interleukin 2, irrespective of CD8 or CD4 phenotype, and could be extensively expanded in vitro without losing their peculiar functional features. The feasibility of our approach for in vitro separation of GVL from GVH reaction opens perspectives for using TCCs, which are selectively reactive towards leukemia blasts, for antileukemia adoptive immune therapy approaches after hematopoietic stem cell transplantation, in particular from HLA-mismatched donors.

An inflammatory checkpoint regulates recruitment of graft-versus-host reactive T cells to peripheral tissues

Transfer of T cells to freshly irradiated allogeneic recipients leads to their rapid recruitment to nonlymphoid tissues, where they induce graft-versus-host disease (GVHD). In contrast, when donor T cells are transferred to established mixed chimeras (MCs), GVHD is not induced despite a robust graft-versus-host (GVH) reaction that eliminates normal and malignant host hematopoietic cells. We demonstrate here that donor GVH-reactive T cells transferred to MCs or freshly irradiated mice undergo similar expansion and activation, with similar up-regulation of homing molecules required for entry to nonlymphoid tissues. Using dynamic two-photon in vivo microscopy, we show that these activated T cells do not enter GVHD target tissues in established MCs, contrary to the dogma that activated T cells inevitably traffic to nonlymphoid tissues. Instead, we show that the presence of inflammation within a nonlymphoid tissue is a prerequisite for the trafficking of activated T cells to that site. Our studies help to explain the paradox whereby GVH-reactive T cells can mediate graft-versus-leukemia responses without inducing GVHD in established MCs.

Light chain editing generates polyreactive antibodies in chronic graft-versus-host reaction

The chronic graft-versus-host (cGvH) reaction is a model of induced lupus caused by alloreactive CD4(+) T cells from a Bm-12 mouse in a C57BL/6 recipient. We used this cGvH reaction in C57BL/6 anti-DNA H chain transgenic mice, 56R/B6, to understand the structure, specificity, and origin of the induced autoantibodies (auto-Abs). We found anti-DNA Abs that reacted to several different antigens, such as phosphatidylserine, myelin basic protein, thyroglobulin, histone, insulin, cytochrome C, and beta-galactosidase. This polyreactivity was found for Abs from B cells that expressed the 56R H chain transgene with "editor" L chains that did not completely veto autoreactivity. We suggest that such incomplete editing results in polyreactivity and that incompletely edited polyreactive B cells influence the subsequent expression of pathogenic auto-Abs in disease. We also found B cells that coexpress kappa and lambda L chain. These B cells contributed to the autoimmune response and are possibly in the marginal zone of the spleen.

Analysis of serum granulysin in patients with hematopoietic stem-cell transplantation: its usefulness as a marker of graft-versus-host reaction

Granulysin is a newly identified CTL/NK cell-related cytotoxic protein, which is secreted in both constitutive and Ca-dependent manner. To evaluate its significance in stem-cell transplantation (SCT), serum granulysin was measured by newly established ELISA method in 26 patients undergoing SCT (21 allogeneic and 5 autologous). In the allogeneic SCT, granulysin was transiently increased in 3 weeks, which was not observed in autologous SCT. In acute GVHD, serum granulysin was markedly increased and correlated with the severity of GVHD. Elevation of granulysin was not necessarily associated with increase of sIL2R or IFN-gamma. In vitro, allospecific T cells released granulysin in an allo-specific manner, and it was correlated with allo-specific cytotoxic activity. These results indicate that increased release of granulysin presents alloreactivity and serum granulysin is useful as a marker of GVHD in SCT.

Immune responses to an encapsulated allogeneic islet β-cell line in diabetic NOD mice

Our goal is to develop effective islet grafts for treating type 1 diabetes. Since human islets are scarce, we evaluated the efficacy of a microencapsulated insulin-secreting conditionally transformed allogeneic beta-cell line (betaTC-tet) in non-obese diabetic mice treated with tetracycline to inhibit cell growth. Relatively low serum levels of tetracycline controlled proliferation of betaTC-tet cells without inhibiting effective control of hyperglycemia in recipients. There was no significant host cellular reaction to the allografts or host cell adherence to microcapsules, and host cytokine levels were similar to those of sham-operated controls. We conclude that encapsulated allogeneic beta-cell lines may be clinically relevant, because they effectively restore euglycemia and do not elicit a strong cellular immune response following transplantation. To our knowledge, this is the first extensive characterization of the kinetics of host cellular and cytokine responses to an encapsulated islet cell line in an animal model of type 1 diabetes.

The unfinished legacy of liver transplantation: emphasis on immunology

Liver transplantation radically changed the philosophy of hepatology practice, enriched multiple areas of basic science, and had pervasive ripple effects in law, public policy, ethics, and theology. Why organ engraftment was feasible remained enigmatic, however, until the discovery in 1992 of donor leukocyte microchimerism in long-surviving liver, and other kinds of organ recipients. Following this discovery, the leukocyte chimerism-associated mechanisms were elucidated that directly linked organ and bone marrow transplantation and eventually clarified the relationship of transplantation immunology to the immunology of infections, neoplasms, and autoimmune disorders. We describe here how the initially controversial paradigm shift mandated revisions of cherished dogmas. With the fresh insight, the reasons for numerous inexplicable phenomena of transplantation either became obvious or have become susceptible to discriminate experimental testing. The therapeutic implications of the "new immunology" in hepatology and in other medical disciplines, have only begun to be explored. Apart from immunology, physiologic investigations of liver transplantation have resulted in the discovery of growth factors (beginning with insulin) that are involved in the regulation of liver size, ultrastructure, function, and the capacity for regeneration. Such studies have partially explained functional and hormonal relationships of different abdominal organs, and ultimately they led to the cure or palliation by liver transplantation of more than 2 dozen hepatic-based inborn errors of metabolism. Liver transplantation should not be viewed as a purely technologic achievement, but rather as a searchlight whose beams have penetrated the murky mist of the past, and continue to potentially illuminate the future.

Graft rejection after unrelated donor hematopoietic stem cell transplantation for thalassemia is associated with nonpermissive HLA-DPB1 disparity in host-versus-graft direction

The success of allogeneic hematopoietic stem cell transplantation (HSCT) from matched unrelated donors (UDs) for beta-thalassemia may be hampered by the occurrence of graft rejection. Here, we show that the rate of this complication can be reduced by selecting 5-loci HLA-matched donors without nonpermissive mismatches at HLA-DPB1, defined according to an algorithm previously described and based on principles of central T-cell tolerance. Seventy-two consecutive patients and their UDs, prospectively selected for matching at the allelic level for HLA-A, -B, -C, -DRB, and -DQB1 loci, were enrolled in the analysis. These pairs were either DPB1 matched/permissively mismatched (n = 45, control group) or had at least one nonpermissive DPB1 mismatch in the host-versus-graft (HvG; n = 17) or in the graft-versus-host (GvH; n = 10) direction. In multivariate analysis, the risk of rejection was significantly increased in the group with HvG disparity (RR = 7.42; 95% CI = 1.29-42.68; P = .02) as compared to the control group. A lower, statistically significant, probability of thalassemia-free survival was found in patients belonging to the HvG group as compared to controls (RR = 5.15; 95% CI = 1.58-16.82; P = .01). These data suggest that in patients with thalassemia, the incidence of graft failure after HSCT may be reduced by appropriate selection of UDs, with such selection taking into account the functional rules of immunogenetics.

Effects of preparations modifying Th1/Th2 ratio on the incidence of clinical variants of chronic graft-versus-host reaction

Induction of chronic graft-versus-host reaction in a semiallogenic DBA/2- (DBA/2xC57Bl/6) F1 system leads to the development of Th1- or Th2-dependent immunopathologies. Modification of the Th1/Th2 ratio during induction with preparations acting on the immune system cells via different mechanisms and shifting the Th1/Th2 balance towards Th2 (bisphenol A, pentoxifylline, muramyl dipeptide) increases the incidence of Th2-dependent autoimmune lupus-like glomerulonephritis.

Influence of T-cell depletion on chronic graft-versus-host disease: results of a multicenter randomized trial in unrelated marrow donor transplantation

Donor-derived T cells have been proposed to play a role in pathogenesis of chronic graft-versus-host disease (cGVHD). The impact of ex vivo T-cell depletion (TCD) on cGVHD was analyzed in a randomized multicenter trial involving unrelated donor marrow transplants. A total of 404 patients diagnosed with hematologic malignancies received a total body irradiation-based myeloablative conditioning regimen. GVHD prophylaxis included TCD plus cyclosporine (CSA) or unmodified grafts with CSA plus methotrexate (M/C). Median recipient age was 31.2 years (range, 0.5-55.6 years); median follow-up time since randomization was 4.2 years. The mean number of T cells infused was 1 log lower on the TCD arm. The incidence of cGVHD at 2 years was similar between the TCD and M/C arms, 29% versus 34% (P = .27), respectively. Survival at 3 years from diagnosis of cGVHD was also similar, (TCD 51% versus M/C 58%; P = .29). The proportion of patients with cGVHD who discontinued immunosuppression at 5 years was not different (TCD 72% versus M/C 63%; P = .27), and incidence of serious infections and leukemia relapse were similar on both treatment arms. In spite of a significant reduction of acute GVHD, TCD did not reduce the incidence of cGVHD or improve survival in patients who developed cGVHD.

Cyclosporine treatment of high dose and long duration reduces the severity of graft coronary artery disease in rodent cardiac allografts

BACKGROUND

Graft coronary artery disease (GCAD) limits allograft survival after cardiac transplantation. The objective of this study was to correlate GCAD with the level of immunosuppression in an established allogeneic rodent cardiac chronic rejection model to better understand the mechanisms of GCAD in this system.

METHODS

Donor PVG hearts were transplanted into the abdomen of ACI rats. Six recipient groups received either 10, 7.5 or 5 mg/kg/day of oral cyclosporine (CsA), for 90 (10 mg/90 d, 7.5 mg/90 d, 5 mg/90 d) or 10 days (10 mg/10 d, 7.5 mg/10 d, 5 mg/10 d; n = 10 all groups), and grafts procured on Day 90. GCAD was assessed by histology for percent luminal narrowing (%LN), percent affected vessels (%AV) and intima/media ratio (I/M ratio). Sections were stained for ED1-positive macrophages and MHC Class II-positive cells.

RESULTS

The 10 mg/90 d treatment group showed significantly reduced GCAD compared with the 5mg/10d treatment group (%LN = 4.3 +/- 3.1% vs 39 +/- 11.9%, p < 0.05). The 7.5 mg/90 d group had a reduced %LN and I/M ratio compared with the 5 mg/10 d group (%LN = 8.0 +/- 3.5% vs 39 +/- 11.9%, p < 0.05; I/M ratio = 0.06 +/- 0.02 vs 0.41 +/- 0.14, p < 0.05). There was a trend toward reduction of GCAD with both increasing the dose of CsA as well as the duration of treatment. Continuous treatment with CsA reduced perivascular macrophage and MHC II cell infiltration. Macrophage infiltrates correlated strongly with GCAD (R(2) > 0.90, p < 0.01), and MHC II infiltrates showed a weak correlation, although not statistically significant (R(2) > 0.56, p = NS).

CONCLUSIONS

This study further defines the effect of cyclosporine on GCAD in this cardiac transplantation model. In this system, higher dose and longer duration of treatment with CsA markedly reduces macrophage and MHC II infiltration, correlating with diminished GCAD. However, increasing dose and duration of CsA did not completely eliminate the development of GCAD. Non-immunologic factors could contribute to this occurrence.

Levels of Anti-A/B Antibodies After ABO-Incompatible Hematopoietic Stem Cell Transplantation

In contrast to solid organ transplantation, ABO incompatibility is generally not associated with survival differences in hematopoietic stem cell transplantation. Therefore, patients receiving ABO-incompatible stem cell transplantation can be analyzed to study the mechanism of tolerance induction after antigen-mismatched transplantation. The goal of this study was to analyze the levels of anti-A/B antibodies after ABO-incompatible transplantation. Host-derived antidonor antibodies disappeared rapidly after transplantation and did not reappear in the further posttransplant course. Donor-derived antihost antibodies did not significantly increase and compatible anti-A/B antibodies remained positive after hematopoietic stem cell transplantation. Thus, there is no evidence for stimulation of donor B lymphocytes to produce antirecipient antibodies suggesting a potential B cell tolerance.

Chimerism studies in HLA-identical nonmyeloablative hematopoietic stem cell transplantation point to the donor CD8(+) T-cell count on day + 14 as a predictor of acute graft-versus-host disease

Chimerism analysis of hematopoietic cells has emerged as an essential tool in nonmyeloablative hematopoietic stem cell transplantation. We have investigated the development of donor chimerism in granulocytes and CD4(+) and CD8(+) T cells in blood and bone marrow of 24 patients with hematologic malignancies who received HLA-identical sibling peripheral blood stem cell grafts after conditioning with fludarabine and 2 Gy of total body irradiation. The T-cell chimerism of blood and bone marrow was tightly correlated. Complete donor chimerism was reached earlier in the granulocytes than in the T cells. Mixed T-cell chimerism was common at the time of onset of acute graft-versus-host disease (aGVHD), and both CD4(+) and CD8(+) donor T-cell chimerism increased with the occurrence of aGVHD grades II to IV (P =.0002 and P =.019, respectively). The rate of disappearance of recipient CD8(+) T cells was faster in patients with aGVHD grades II to IV than in patients without clinically significant aGVHD (P =.016). This observation indicates a role of graft-versus-lymphohematopoietic tissue reactions in creating complete donor T-cell chimerism. A donor CD8(+) T-cell count above the median on day +14 increased the risk of subsequent development of aGVHD grades II to IV (P =.003).

Avian thymic hormone treatment of peripheral blood mononuclear cells from young chicks stimulates acute graft-versus-host reaction in chicken embryos

Avian thymic hormone (ATH) is a parvalbumin produced by epithelial cells in the thymic cortex of chickens and circulates in the blood on a 5-day cycle. It stimulates precocious development of cell-mediated immunity. The effect of partially purified extracts of thymus (TE) and purified ATH were tested for their effect on the acute graft-versus-host reaction (GVHR). Treatment of chicks for their first 3-days of life did not enhance the acute GVHR produced by their PBMC in 14-day-old embryos. PBMC from 3-day-old chicks were treated in vitro with TE, ATH, thymosin fraction 5 or thymosin alpha1 for 2 h and injected into 14-day-old embryos. Bone marrow cells and thymic lymphocytes were treated with TE. Only PBMC treated with TE or ATH produced an enhanced acute GVHR. Because ATH targets gammadelta T cells, the data implicate participation of donor gammadelta T cells in the acute GVHR.

Minor histocompatibility antigens: allo target molecules for tumor-specific immunotherapy

Minor histocompatibility antigens have to be considered as key molecules in the stem cell-based immunotherapy of malignancies. Allogeneic stem cell transplantation (SCT) is a well-established and effective therapy for advanced hematologic malignancies. The apparent powerful graft-versus-leukemia effect of SCT led clinicians to apply SCT for the treatment of metastatic solid tumors. The SCT-based graft-versus-tumor reaction in the allogeneic human leukocyte antigen-matched SCT setting is mediated by allo-immune effectorcells directed against tumor-related target antigens. The target molecules involved in the allo-immune graft-versus-tumor reaction are tumor-specific antigens, tumor-associated antigens, and tissue- and cell-specific minor histocompatibility antigens. The power of the minor histocompatibility antigens in the human leukocyte antigen-identical, stem cell-based immunotherapy for malignancies is their "allo-ness." As opposed to tumor-associated self antigens, the complexes of MHC and allo-target peptide are likely to be more immunogeneic than the major histocompatibility complex and self-target peptide complexes. Moreover, minor histocompatibility allo-antigens are not subject to self tolerance. Earlier minor histocompatibility antigens were seen as alien entities, disturbing the success of the so ideally matched organ and SCT donor-recipient combinations. To date, minor histocompatibility antigens can be set in the favorable light of useful tools for immunotherapy for cancer. The first clinical application of the hematopoietic minor histocompatibility antigens HA-1 and HA-2 is currently being explored in a stem cell-based setting for hematologic malignancies. Because HA-1 is also expressed on carcinoma cells, a stem cell-based vaccination trial for patients with metastatic breast or renal cancer is about to start as well. The immunotherapeutic potential of minor histocompatibility antigens demands serious searches for new minor histocompatibility antigens and analyses of their phenotype frequency, tissue distribution, and functional membrane expression. The minor histocompatibility antigens meeting the prerequisites for specific immunotherapy for malignancies, such as membrane expression and tissue and/or cell specificity, may offer the curative tools for stem cell-based immunotherapy for various hematologic and nonhematologic malignancies.

The anti-DNA knock-in model of systemic autoimmunity induced by the chronic graft-vs-host reaction

The injection of spleen cells from bm12 mice into C57BL/6 recipients induces a chronic graft-vs-host reaction characterized by systemic autoimmunity, including anti-double-stranded DNA (anti-dsDNA) autoantibodies and immune complex-type proliferative glomerulonephritis. If the B6 recipient mice express an anti-DNA Vh site-directed transgene, the repertoire is skewed even more toward the anti-DNA response. Over a period of several weeks, high titers of serum anti-DNA antibodies appear and the mice develop renal damage. This permits the examination of the role of somatic immunoglobulin genetics and B-cell tolerance in a model of systemic lupus erythematosus.

[Role of killer cell immunoglobulin-like receptors (KIR) in human diseases]

The genetics and physiological role of killer cell immunoglobulin-like receptors (KIR) are briefly reviewed. Haplotype polymorphism of KIR genes resulting in different proportions of genes coding for activatory and inhibitory receptors is emphasized. The participation of KIR molecules in the reactions of natural killer (NK) cells and subpopulations of T lymphocytes is described. Human diseases, in which a contribution of KIR has been found or suspected are listed. Study designs on KIR for realization in Poland are proposed.

Positive and negative selection of T cell repertoires during differentiation in allogeneic bone marrow chimeras

T cells acquire immune functions during expansion and differentiation in the thymus. Mature T cells respond to peptide antigens (Ag) derived from foreign proteins when these peptide Ag are presented on the self major histocompatibility complex (MHC) molecules but not on allo-MHC. This is termed self-MHC restriction. On the other hand, T cells do not induce aggressive responses to self Ag (self-tolerance). Self-MHC restriction and self-tolerance are not genetically determined but acquired a posteriori by positive and negative selection in the thymus in harmony with the functional maturation. Allogeneic bone marrow (BM) chimera systems have been a useful strategy to elucidate mechanisms underlying positive and negative selection. In this communication, the contribution of BM chimera systems to the investigation of the world of T-ology is discussed.

Unexpected role of TNF-alpha in graft versus host reaction (GVHR): donor-derived TNF-alpha suppresses GVHR via inhibition of IFN-gamma-dependent donor type-1 immunity

Graft versus host disease (GVHD) is a major complication of allogeneic hematopoietic stem cell transplantation, leading to significant morbidity and mortality. Host-derived TNF-alpha play a role in the induction of allo-reactive donor T cell activation and the pathogenesis of GVHD. On the other hand, the precise role of donor-derived TNF-alpha in GVHD remains unclear. To elucidate this issue, we designed an acute GVHD model using (B6 x D2) F1 recipient mice transferred with spleen cells derived from either wild-type or TNF-alpha(-/-) C57BL/6 mice. Surprisingly, we found that spleen cells from TNF-alpha(-/-) mice induce more severe graft versus host reaction (GVHR) than wild-type spleen cells upon transfer into B6D2F1 mice. Transplantation of TNF-alpha(-/-) mouse spleen cells was associated with enhanced anti-host CTL generation and augmented deletion of host cells. Moreover, mice receiving TNF-alpha(-/-) cells showed significantly higher levels of serum IFN-gamma, which was mainly produced by donor CD8+ T cells. We also demonstrated that TNF-alpha deficiency in donor spleen cells caused a marked elevation of TNF-alpha producing capacity by LPS-stimulated host macrophages. Such enhanced GVHR was completely prevented by using TNF-alpha(-/-)IFN-gamma(-/-) splenic cells. Our findings demonstrate, for the first time, that donor-derived TNF-alpha suppress GVHR by inhibiting IFN-gamma-dependent donor type-1 immunity which is essential for host TNF-alpha elevation.

Graft-versus-host-reactive donor CD4 cells can induce T cell-mediated rejection of the donor marrow in mixed allogeneic chimeras prepared with nonmyeloablative conditioning

Murine mixed hematopoietic chimerism can be achieved following nonmyeloablative conditioning with cyclophosphamide, T cell–depleting monoclonal antibodies, and thymic irradiation. Donor lymphocyte infusions (DLIs) 35 days after bone marrow transplantation (BMT) convert mixed to full donor chimerism and mediate graft-versus-lymphoma effects without graft-versus-host disease. We evaluated the role of T-cell subsets in DLIs in converting mixed to full donor chimerism in a fully major histocompatibility complex–mismatched strain combination. Whereas DLIs administered on day 35 converted 100% of mixed chimeras to full donor chimerism, conversion was less frequent when either CD4 or CD8 cells were depleted, indicating that both subsets contribute to the conversion. Surprisingly, administration of CD8-depleted DLIs led to complete loss of donor chimerism in a high proportion (54%) of recipients compared with CD4-plus CD8-depleted DLIs (15%) or CD4-depleted DLIs (0%) (P &lt; .05). DLIs administered at early time points after BMT (eg, day 21) also precipitated rejection of donor marrow by recipient αβ T cells, in association with donor CD4 cell expansion and high production of interleukin 2 (IL-2), IL-4, and interferon-γ. Thus, DLIs can paradoxically induce marrow rejection by residual host αβ T cells. These results have implications for the timing of and use of subset depletion of DLIs in recipients of nonmyeloablative transplants.

Haemato-biochemical and immuno-pathophysiological effects of chronic toxicity with synthetic pyrethroid, organophosphate and chlorinated pesticides in broiler chicks

Haemato- biochemical and immuno-pathophysiological changes following feeding of broiler chicks with 20 ppm fenvalerate (synthetic pyrethroid, SP), 2 ppm monocrotophos (organophosphate, OP) and 2 ppm endosulfan (chlorinated hydrocarbon, CH) were studied. Four groups of broiler birds (30 each) were fed poultry mash without (control) or mixed with pesticides for 8 weeks. Blood glucose, serum globulin and acetyl cholinesterase (AChE) activity level were decreased (P<0.01) in all treated groups compared to control, but not the serum albumin and BUN. The total ATPase activity was enhanced (P<0.01) in fenvalerate and monocrotophos than birds in control group. Body weight, total erythrocyte count, packed cell volume, haemoglobin, eosinophil and monocyte count did not show any changes. Total leucocytes and T-lymphocyte count was lower (P<0.01) in all treated groups as compared to control group. B-cell count (P<0.01), mean 2-4-dinitrofluorobenzene (DNFB) dermal sensitivity score and splenic indices from graft vs. host reaction (P<0.05) were decreased in fenvalarate and endosulfan but the values for monocrotophos were intermediate between control and other treated groups. Pesticide intoxication reduced nitroblue tetrazolium (NBT) positive cells (active splenic macrophages) (P<0.05) and spleen weight (P<0.01). Whereas bursal weight was reduced only with endosulfan, thymic weight was reduced on endosulfan and fenvalerate-treated feed. Microscopic examination of these organs further revealed atrophy/hypoplasia, decrease in the size of follicles with depletion of lymphocytes and haemorrhages in thymus. The study concludes that the chronic exposure of chicks to small amount of SP, OP and CH pesticide leads to deleterious effects on metabolism and immune system of birds.

Prolonged imiquimod treatment and graft-versus-host reaction: histological mimicry in the skin infiltration pattern of the monocyte-macrophage-dendrocyte lineage

Factor-XIIIa-positive dendrocytes belong to the monocyte-macrophage-dendrocyte (MMD) lineage which is considered to play a pivotal role in the skin response to the immune response modifier imiquimod. The same cells are also boosted in low-grade graft-versus-host reaction (GVHR) with skin manifestations. Both conditions are characterized by specific epidermal damage. The aim of the present study was to compare them using immunohistochemistry to identify MMD subsets and other inflammatory cells in the dermis. We compared 3 cases of long-term (4, 9 and 11 months) imiquimod topical applications on normal skin, 25 low-grade GVHR controlled by immunosuppressive therapy and 25 control cases with normal skin. Compared to the normal dermis, cells of the MMD lineage were considerably boosted in the dermis of GVHR and at the imiquimod-treated sites. By contrast, only minimal accumulations of lymphocytes and Langerhans cells were disclosed in the dermis. The pattern of dermal infiltration by MMD cells was similar in GVHR and after imiquimod treatment. However, intraindividual differences in densities were obvious irrespective of the skin condition. In conclusion, there is great mimicry in the MMD involvement in the dermis during low-grade GVHR and after chronic applications of imiquimod.

CD8+ immunoregulatory cells in the graft-versus-host reaction: CD8 T cells activate dendritic cells to secrete interleukin-12/interleukin-18 and induce T helper 1 autoantibody

Initiation of cell-mediated immunity or autoimmunity requires secretion of interleukin (IL)-12 from dendritic cells (DC), which drives the generation of T helper 1 (Th1) effector cells in synergy with IL-18. Induction of IL-12 can be triggered by microbial stimuli but also requires signals from activated T cells. We investigated interactions between alloreactive CD4 and CD8 T cells in mixed lymphocyte reactions (MLR) in vitro and in the graft-versus-host reaction (GVHR) in vivo. In a parent-into-F1 model of GVHR, donor CD8 cells were found to suppress the hyper-immunoglobulin E (IgE) syndrome, anti-DNA immunoglobulin G1 (IgG1) autoantibodies and donor CD4-cell expansion, but were essential for Th1-dependent immunoglobulin G2a (IgG2a) autoantibody production and release of serum IL-12 p40. In vitro, addition of alloreactive CD8 cells to CD4 cells and mature DC enhanced Th1 development. CD4 and CD8 T cells induced IL-18 from DC and primed for IL-12 p70 secretion via interferon-gamma (IFN-gamma) or tumour necrosis factor-alpha (TNF-alpha). However CD8 T cells, but not CD4 cells, released IFN-gamma/TNF-alpha after primary stimulation. The data suggest that rapid release of inflammatory cytokines from central memory-type CD8 cells early in immunity is critical for induction of Th1 cells via DC activation and IL-12 production. This pathway could provide a means for amplification of cell-mediated autoimmunity in the absence of microbial stimuli.