Antigen presentation and immune regulatory capacity of immature and mature-enriched antigen presenting (dendritic) cells derived from human bone marrow

Prevention of non-infectious pulmonary complications after intra-bone marrow stem cell transplantation in mice

Non-infectious pulmonary complications including idiopathic pneumonia syndrome (IPS) and bronchiolitis obliterans syndrome (BOS), which are clinical and diagnostic manifestations of lung chronic graft-versus-host disease (GVHD), cause significant mortality after allogeneic stem cell transplantation (SCT). Increasing evidence suggests that alloantigen reactions in lung tissue play a central role in the pathogenesis of IPS and BOS; however, the mechanism is not fully understood. Several clinical and experimental studies have reported that intra-bone marrow (IBM)-SCT provides high rates of engraftment and is associated with a low incidence of acute GVHD. In the present study, allogeneic SCT was conducted in mouse models of IPS and BOS, to compare intravenous (IV)-SCT with IBM-SCT. Allogeneic IBM-SCT improved the clinical and pathological outcomes of pulmonary complications compared to those of IV-SCT. The mechanisms underlying the reductions in pulmonary complications in IBM-SCT mice were explored. The infiltrating lung cells were mainly CD11b+ myeloid and CD3+ T cells, in the same proportions as in transplanted donor cells. In an in vivo bioluminescence imaging, a higher proportion of injected donor cells was detected in the lung during the early phase (1 h after IV-SCT) than after IBM-SCT (16.7 ± 1.1 vs. 3.1 ± 0.7 × 10⁵ photons/s/animal, IV-SCT vs. IBM-SCT, P = 1.90 × 10⁻¹⁰). In the late phase (5 days) after SCT, there were also significantly more donor cells in the lung after IV-SCT than after IBM-SCT or allogeneic-SCT (508.5 ± 66.1 vs. 160.1 ± 61.9 × 10⁶ photons/s/animal, IV-SCT vs. IBM-SCT, P = 0.001), suggesting that the allogeneic reaction induces sustained donor cell infiltration in the lung during the late phase. These results demonstrated that IBM-SCT is capable of reducing injected donor cells in the lung; IBM-SCT decreases donor cell infiltration. IBM-SCT therefore represents a promising transplantation strategy for reducing pulmonary complications, by suppressing the first step in the pathophysiology of chronic GVHD.

Mannose-Modified Serum Exosomes for the Elevated Uptake to Murine Dendritic Cells and Lymphatic Accumulation

The surface of bovine serum-derived exosomes (EXOs) are modified with α-d-mannose for facile interaction with mannose receptors on dendritic cells (DCs) and for efficient delivery of immune stimulators to the DCs. The surface of the EXOs is modified with polyethylene glycol (PEG) without particle aggregation (≈50 nm) via the incorporation of 1,2-distearoyl-sn-glycero-3-phosphoethanolamine (DSPE) into the lipid layer of the EXO, compared to chemical conjugation by N-hydroxysuccinimide activated PEG (NHS-PEG). PEG modification onto the exosomal surface significantly decreases the non-specific cellular uptake of the EXOs into the DCs. However, the EXOs with mannose-conjugated PEG-DSPE (EXO-PEG-man) exhibit excellent intracellular uptake into the DCs and boost the immune response by the incorporation of adjuvant, monophosphoryl lipid A (MPLA) within the EXO. After an intradermal injection, a higher retention of EXO-PEG-man is observed in the lymph nodes, which could be used for the efficient delivery of immune stimulators and antigens to the lymph nodes in vivo.

[Study on the immune functions of dendritic cells regulated by histone deacetylase inhibitor Belinostat]

Objective: To explore effects of histone deacetylase inhibitor Belinostat on the immunologic function of dendritic cells (DC) and its possible mechanism. Methods: Cultured mouse bone marrow-derived DC from C57BL/6 mouse in vitro. The experiments were divided into 0, 50, 100 nmol/L Belinostat + immature DC (imDC) group, and 0, 50, 100 nmol/L Belinostat mature DC (mDC). The changes of the ultrastructure of DC were observed by transmission electron microscope (TEM). Immunophenotype and CCR7 expression rate were detected by FCM, and the migration rate was observed by chemotaxis assay. The proliferation of lymphocytes stimulated by different DC was detected by mixed lymphocyte culture reaction. The cytokines in the culture supernatant, including TNF-α, IL-12 and IL-10, were examined by ELISA. RQ-PCR was used to examine the relative expression of mRNA in RelB. Results: Successful cultured and identified the qualified imDC and mDC. Belinostat decreased the expression of CCR7 on imDC [(25.82±7.25)% vs (50.44±5.61)% and (18.71±2.00)% vs (50.44±5.61)%], meanwhile increased the rate on mDC [(71.14±1.96)% vs (64.90±1.47)%]. Chemotaxis assay showed that the migration rate of Belinostat+imDC and Belinostat+mDC group were both decreased, but the difference in imDC was not significant. T lymphocyte proliferation rate stimulated by 100 nmol/L Belinostat+imDC group was lower than imDC group in condition irritation cell∶reaction cell=1∶2 [(227.09±13.49)% vs (309.49±53.69)%]. Belinostat significantly suppressed the secretion of cytokines TNF-α, IL-12 and IL-10 (all P<0.01). The relative expression of mRNA in RelB was slightly decreased in Belinostat+imDC and Belinostat+mDC group (all P<0.05). Conclusion: Belinostat could effectly suppress DC maturation and regulate immune tolerance of DC, which may be due to the down-regulation of mRNA level of RelB in DC.

Prolongation of kidney allograft survival regulated by indoleamine 2, 3-dioxygenase in immature dendritic cells generated from recipient type bone marrow progenitors

Immature dendritic cells (iDCs) are bone marrow-derived professional antigen-presenting cells, exhibit very low levels of the co-stimulatory molecules CD80 (B7-1), CD86 (B7-2), and CD40 and major histocompatibility complex (MHC) class II and play a critical role in triggering antigen-specific immunotolerance. The enzyme indoleamine 2, 3-dioxygenase (IDO) is a cytosolic tryptophan catabolism rate-limiting step enzyme. IDO secreted by DCs shows an association with the suppression of T-cell responses and promotion of tolerance. In this study, BN rat recipients were pre-injected with donor renal alloantigen-treated recipient iDCs before kidney transplantation. The renal allograft exhibited a lighter renal rejection response, prolonged graft survival time, and an increasing content of CD4⁺CD25⁺Foxp3⁺ regulatory T cells (Tregs). Additionally, up-regulated secretion of Th2 cytokines were found in recipient sera post-transplantation. Transfection of si-IDO1 RNA into renal-antigen-treated recipient iDCs reversed these changes, which suggested that IDO channel signaling may be involved in iDC-induced allograft immunotolerance. These results suggested that iDC-induced and IDO-mediated allograft immunotolerance might be a potentially feasible tactic to prolong allograft survival, in addition to immunosuppressive drugs.

Internalization and presentation of myelin antigens by the brain endothelium guides antigen-specific T cell migration

Trafficking of myelin-reactive CD4(+) T-cells across the brain endothelium, an essential step in the pathogenesis of multiple sclerosis (MS), is suggested to be an antigen-specific process, yet which cells provide this signal is unknown. Here we provide direct evidence that under inflammatory conditions, brain endothelial cells (BECs) stimulate the migration of myelin-reactive CD4(+) T-cells by acting as non-professional antigen presenting cells through the processing and presentation of myelin-derived antigens in MHC-II. Inflamed BECs internalized myelin, which was routed to endo-lysosomal compartment for processing in a time-dependent manner. Moreover, myelin/MHC-II complexes on inflamed BECs stimulated the trans-endothelial migration of myelin-reactive Th1 and Th17 2D2 cells, while control antigen loaded BECs did not stimulate T-cell migration. Furthermore, blocking the interaction between myelin/MHC-II complexes and myelin-reactive T-cells prevented T-cell transmigration. These results demonstrate that endothelial cells derived from the brain are capable of enhancing antigen-specific T cell recruitment.

Plant components for immune modulation targeting dendritic cells: implication for therapy

Medicinal plant utilization is as old as human life. There are thousands of herbs consumed for medicinal purposes all over the world, especially in east. Their value has not decreased over time and many modern pharmaceuticals have originated from traditional medicinal plants. Studying the reason for their influence is an attractive field of medicine. Among various types of herbs, some function via their immunomodulatory effects. Experiments have shown the regulatory influences of several plants on each type of immune cell, including T cells, B cells, dendritic cells (DCs), macrophages and NK cells. Because of the prominent role of DCs in antigen presentation as the major APC, this review summarizes the immunomodulatory effects of some plants performed through DC effects.

Regulatory dendritic cells for immunotherapy in immunologic diseases

We recognize well the abilities of dendritic cells to activate effector T cell (Teff cell) responses to an array of antigens and think of these cells in this context as pre-eminent antigen-presenting cells, but dendritic cells are also critical to the induction of immunologic tolerance. Herein, we review our knowledge on the different kinds of tolerogenic or regulatory dendritic cells that are present or can be induced in experimental settings and humans, how they operate, and the diseases in which they are effective, from allergic to autoimmune diseases and transplant tolerance. The primary conclusions that arise from these cumulative studies clearly indicate that the agent(s) used to induce the tolerogenic phenotype and the status of the dendritic cell at the time of induction influence not only the phenotype of the dendritic cell, but also that of the regulatory T cell responses that they in turn mobilize. For example, while many, if not most, types of induced regulatory dendritic cells lead CD4⁺ naïve or Teff cells to adopt a CD25⁺Foxp3⁺ Treg phenotype, exposure of Langerhans cells or dermal dendritic cells to vitamin D leads in one case to the downstream induction of CD25⁺Foxp3⁺ regulatory T cell responses, while in the other to Foxp3⁻ type 1 regulatory T cells (Tr1) responses. Similarly, exposure of human immature versus semi-mature dendritic cells to IL-10 leads to distinct regulatory T cell outcomes. Thus, it should be possible to shape our dendritic cell immunotherapy approaches for selective induction of different types of T cell tolerance or to simultaneously induce multiple types of regulatory T cell responses. This may prove to be an important option as we target diseases in different anatomic compartments or with divergent pathologies in the clinic. Finally, we provide an overview of the use and potential use of these cells clinically, highlighting their potential as tools in an array of settings.

Periodontal disease immunology: 'double indemnity' in protecting the host

During the last two to three decades our understanding of the immunobiology of periodontal disease has increased exponentially, both with respect to the microbial agents triggering the disease process and the molecular mechanisms of the host engagement maintaining homeostasis or leading to collateral tissue damage. These foundational scientific findings have laid the groundwork for translating cell phenotype, receptor engagement, intracellular signaling pathways and effector functions into a 'picture' of the periodontium as the host responds to the 'danger signals' of the microbial ecology to maintain homeostasis or succumb to a disease process. These findings implicate the chronicity of the local response in attempting to manage the microbial challenge, creating a 'Double Indemnity' in some patients that does not 'insure' health for the periodontium. As importantly, in reflecting the title of this volume of Periodontology 2000, this review attempts to inform the community of how the science of periodontal immunology gestated, how continual probing of the biology of the disease has led to an evolution in our knowledge base and how more recent studies in the postgenomic era are revolutionizing our understanding of disease initiation, progression and resolution. Thus, there has been substantial progress in our understanding of the molecular mechanisms of host-bacteria interactions that result in the clinical presentation and outcomes of destructive periodontitis. The science has embarked from observations of variations in responses related to disease expression with a focus for utilization of the responses in diagnosis and therapeutic outcomes, to current investigations using cutting-edge fundamental biological processes to attempt to model the initiation and progression of soft- and hard-tissue destruction of the periodontium. As importantly, the next era in the immunobiology of periodontal disease will need to engage more sophisticated experimental designs for clinical studies to enable robust translation of basic biologic processes that are in action early in the transition from health to disease, those which stimulate microenvironmental changes that select for a more pathogenic microbial ecology and those that represent a rebalancing of the complex host responses and a resolution of inflammatory tissue destruction.

The specialized roles of immature and mature dendritic cells in antigen cross-presentation

Exogenous antigen cross-presentation is integral to the stimulation of cytotoxic T-lymphocytes against viruses and tumors. Central to this process are dendritic cells (DCs), which specialize in cross-presentation. DCs may be considered to exist in two radically different states of activation, generally referred to as immature and mature. In each of these states, the cell has a series of separate and specialized abilities for the induction of T-cell immunity. In the immature state, the DC is adept in surveying the periphery, acquiring and storing antigen, but has a limited capacity for direct T-cell activation. During a brief and defined window of time following DC stimulation, nearly every aspect of antigen handling changes, as it transitions from an entity focused on protein preservation to one capable of efficient cross-presentation. It is this time period and the underlying molecular mechanisms active here, which form the core of our studies on cross-presentation.

'Multi-epitope-targeted' immune-specific therapy for a multiple sclerosis-like disease via engineered multi-epitope protein is superior to peptides

Antigen-induced peripheral tolerance is potentially one of the most efficient and specific therapeutic approaches for autoimmune diseases. Although highly effective in animal models, antigen-based strategies have not yet been translated into practicable human therapy, and several clinical trials using a single antigen or peptidic-epitope in multiple sclerosis (MS) yielded disappointing results. In these clinical trials, however, the apparent complexity and dynamics of the pathogenic autoimmunity associated with MS, which result from the multiplicity of potential target antigens and “epitope spread”, have not been sufficiently considered. Thus, targeting pathogenic T-cells reactive against a single antigen/epitope is unlikely to be sufficient; to be effective, immunospecific therapy to MS should logically neutralize concomitantly T-cells reactive against as many major target antigens/epitopes as possible. We investigated such “multi-epitope-targeting” approach in murine experimental autoimmune encephalomyelitis (EAE) associated with a single (“classical”) or multiple (“complex”) anti-myelin autoreactivities, using cocktail of different encephalitogenic peptides vis-a-vis artificial multi-epitope-protein (designated Y-MSPc) encompassing rationally selected MS-relevant epitopes of five major myelin antigens, as “multi-epitope-targeting” agents. Y-MSPc was superior to peptide(s) in concomitantly downregulating pathogenic T-cells reactive against multiple myelin antigens/epitopes, via inducing more effective, longer lasting peripheral regulatory mechanisms (cytokine shift, anergy, and Foxp3+ CTLA4+ regulatory T-cells). Y-MSPc was also consistently more effective than the disease-inducing single peptide or peptide cocktail, not only in suppressing the development of “classical” or “complex EAE” or ameliorating ongoing disease, but most importantly, in reversing chronic EAE. Overall, our data emphasize that a “multi-epitope-targeting” strategy is required for effective immune-specific therapy of organ-specific autoimmune diseases associated with complex and dynamic pathogenic autoimmunity, such as MS; our data further demonstrate that the “multi-epitope-targeting” approach to therapy is optimized through specifically designed multi-epitope-proteins, rather than myelin peptide cocktails, as “multi-epitope-targeting” agents. Such artificial multi-epitope proteins can be tailored to other organ-specific autoimmune diseases.

Selective serotonin reuptake inhibitors attenuate the antigen presentation from dendritic cells to effector T lymphocytes

Fluoxetine, one of the selective serotonin reuptake inhibitors (SSRIs), has been found to possess immune modulation effects, in addition to its antidepressant effects. However, it remains unclear whether SSRIs can suppress the antigen-presenting function of dendritic cells (DCs). Therefore, Fluoxetine was applied to a co-culture of Aggregatibacter actinomycetemcomitans (Aa)-reactive T cells (×Aa-T) isolated from Aa-immunized mice and DCs. This resulted in the suppressed proliferation of ×Aa-T stimulated with Aa-antigen presentation by DCs. Specifically, Fluoxetine increased the extracellular 5-hydroxytryptamine (5-HT) in the ×Aa-T/DC co-culture, whereas exogenously applied 5-HT promoted T-cell proliferation in the ×Aa-T/DC co-culture, indicating that Fluoxetine-mediated suppression of ×Aa-T/DC responses cannot be attributed to extracellular 5-HT. Instead, Fluoxetine remarkably suppressed the expression of costimulatory molecule ICOS-L on DCs. Fluoxetine also promoted a greater proportion of CD86(Low) immature DCs than CD86(High) mature DCs, while maintaining the expression levels of CD80, MHC-class-II and PD-L1. These results suggested that Fluoxetine suppressed the ability of DCs to present bacterial antigens to T cells, and the resulting T-cell proliferation, in a SERT/5-HT-independent manner and that diminished expression of ICOS-L on DCs and increase of CD86(Low) immature DCs caused by Fluoxetine might be partially associated with Fluoxetine-mediated suppression of DC/T-cell responses.

Phenotypic and functional abnormalities of bone marrow-derived dendritic cells in systemic lupus erythematosus

Introduction

Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by autoreactive T and B cells, which are believed to be secondary to deficient dendritic cells (DCs). However, whether DC abnormalities occur during their development in the bone marrow (BM) or in the periphery is not known.

Methods

Thirteen patients with SLE and 16 normal controls were recruited. We studied the morphology, phenotype, and functional abilities of bone marrow-derived dendritic cells (BMDCs) generated by using two culture methods: FMS-like tyrosine kinase 3 (Flt3)-ligand (FL) and granulocyte-macrophage colony-stimulating factor (GM-CSF) plus interleukin-4 (IL-4), respectively.

Results

BMDCs induced by FL exhibited both myeloid (mDC) and plasmacytoid DC (pDC) features, whereas GM-CSF/IL-4 induced mDC generation. Substantial phenotypic and functional defects of BMDCs were found from patients with SLE at different stages of cell maturation. When compared with healthy controls, SLE immature BM FLDCs expressed higher levels of CCR7. Both immature and mature SLE BM FLDCs expressed higher levels of CD40 and CD86 and induced stronger T-cell proliferation. SLE BM mDCs expressed higher levels of CD40 and CD86 but lower levels of HLA-DR and a lower ability to stimulate T-cell proliferation when compared with control BM mDCs.

Conclusions

Our data are in accordance with previous reports that suggest that DCs have a potential pathogenic role in SLE. Defects of these cells are evident during their development in BM. BM mDCs are deficient, whereas BM pDCs, which are part of BM FLDCs, are the likely culprit in inducing autoimmunity in SLE.

Met-RANTES down-regulates the expression of MIP-3α and CCR6 in the colon of mice with experimental ulcerative colitis

AIM: To investigate the role of macrophage inflammatory protein-3α (MIP-3α) and chemokine receptor 6 (CCR6) in the pathogenesis of ulcerative colitis (UC) and to explore the mechanism of therapeutic effect of Met-RANTES against UC.

METHODS: Forty mice were randomly and equally divided into four groups: blank control group, model control group, normal saline group, and Met-RANTES treatment group. Ulcerative colitis was induced in mice by giving dextran sodium sulfate (DSS). The impact of Met-RANTES on disease activity index (DAI), gross morphological score (GMS) and histopathological score (HPS) in UC was then evaluated. The expression of MIP-3α and CCR6 mRNAs was measured by reverse transcription-polymerase chain reaction (RT-PCR). The expression of MIP-3α and CCR6 proteins was examined by Western blot and immunohistochemistry.

RESULTS: The DAI, GMS and HPS were higher in the model control group and the normal saline group than in the blank control group. The expression levels of MIP-3α and CCR6 mRNAs and proteins in UC were significantly higher in the model control group and the normal saline group than in the blank control group (all P < 0.01). The DAI, GMS and HPS as well as the expression levels of MIP-3α and CCR6 mRNAs and proteins in the Met-RANTES treatment group were significantly lower than those in the model control group and the normal saline group (mRNA: 0.21 ± 0.08 vs 1.09 ± 0.08 and 1.08 ± 0.07, and 0.25 ± 0.08 vs 1.11 ± 0.07 and 1.05 ± 0.08; protein: 0.28 ± 0.08 vs 0.98 ± 0.07 and 1.05 ± 0.06, and 0.25 ± 0.07 vs 1.19 ± 0.07 and 1.15 ± 0.06; all P < 0.01). In contrast, no statistical differences were noted in DAI, GMS and HPS as well as the expression levels of MIP-3α and CCR6 mRNAs and proteins between the model control group and the normal saline group (all P > 0.05).

CONCLUSION: The expression of MIP-3α and its receptor CCR6 is up-regulated in UC, which is closely related with the development and progression of UC. Met-RANTES can down-regulate the expression of MIP-3α and CCR6 and ameliorate inflammatory damage in mice with UC. MIP-3α and CCR6 may represent novel pharmacological targets for treatment of UC.

Developing dendritic cell-based therapies to condition immune responses to novel oncogenic proteins and stem cells

Cancer vaccines have been disappointing when utilized as stand-alone therapy, especially in late disease settings. However, recent clinical studies in prostate cancer have suggested that dendritic cellular (DC) vaccines may impact patient survival, reviving the notion that cancer vaccines can impact established cancer. In this review we will highlight the advances that have been made in the development of DC-based therapies activated by Toll-like receptor agonists with the capacity to condition toward strong Th1 cellular responses, through the production of cytokines and chemokines, and a capacity to induce apoptosis of tumor cells. Used in early cancer settings, these DCs induce clinically effective immune responses, thus shifting the emphasis toward using these cells earlier in the disease process. We will also discuss targeting novel molecules and cancer stem cells that can eliminate cells with high metastatic potential, moving DC-based therapies into mainstream cancer therapy.

Induction of Auto-reactive Regulatory T Cells by Stimulation with Immature Autologous Dendritic Cells

We have shown in ex vivo studies in donor bone marrow-infused kidney transplant recipients, that chimeric cells of either donor or recipient origin taken from the recipient's bone marrow down-regulated the recipient's cellular immune responses. In the present study, we have now induced regulatory T cells from peripheral blood mononuclear cells (PBMC) of renal transplant recipients or laboratory volunteers by multi-stimulation with autologous immature dendritic cell (iDC) enriched populations derived from either bone marrow cells (BMC) of the (immunosuppressed) kidney transplant recipients or PBMC of the laboratory volunteers (i.e., ibDC and ipDC, respectively). These regulatory T cells, induced by ibDC and ipDC, were autoreactive and designated as TAb and TAp with similar phenotypes and functional profiles. They were largely CD4 + CD25high, CD45RA low and CD45RO high, and uniformly expressed intracellular CTLA-4, and message of IL-4, IL-10, Foxp3, and differentially expressed TGFbeta. Their proliferative responses to autologous mature dendritic stimulating cells (mDC) were approximately two-fold stronger than to allogeneic mDC, and to allogeneic mDC were significantly lower than those of (control) autologous TPBL, suggesting an anergic state. TAb and TAp were not cytotoxic to autologous cells expressing Epstein-Barr virus (EBV) antigens, but were able to inhibit (regulate) the effector phase of this TPBL response to both autologous and allogeneic EBV lymphoblasts. This regulation appeared to require cell-to-cell contact.

Induction of inflammatory and immune responses by HMGB1-nucleosome complexes: implications for the pathogenesis of SLE

Autoantibodies against double-stranded DNA (dsDNA) and nucleosomes represent a hallmark of systemic lupus erythematosus (SLE). However, the mechanisms involved in breaking the immunological tolerance against these poorly immunogenic nuclear components are not fully understood. Impaired phagocytosis of apoptotic cells with consecutive release of nuclear antigens may contribute to the immune pathogenesis. The architectural chromosomal protein and proinflammatory mediator high mobility group box protein 1 (HMGB1) is tightly attached to the chromatin of apoptotic cells. We demonstrate that HMGB1 remains bound to nucleosomes released from late apoptotic cells in vitro. HMGB1–nucleosome complexes were also detected in plasma from SLE patients. HMGB1-containing nucleosomes from apoptotic cells induced secretion of interleukin (IL) 1β, IL-6, IL-10, and tumor necrosis factor (TNF) α and expression of costimulatory molecules in macrophages and dendritic cells (DC), respectively. Neither HMGB1-free nucleosomes from viable cells nor nucleosomes from apoptotic cells lacking HMGB1 induced cytokine production or DC activation. HMGB1-containing nucleosomes from apoptotic cells induced anti-dsDNA and antihistone IgG responses in a Toll-like receptor (TLR) 2–dependent manner, whereas nucleosomes from living cells did not. In conclusion, HMGB1–nucleosome complexes activate antigen presenting cells and, thereby, may crucially contribute to the pathogenesis of SLE via breaking the immunological tolerance against nucleosomes/dsDNA.

Activated circulating dendritic cells after hematopoietic stem cell transplantation predict acute graft-versus-host disease

BACKGROUND

Dendritic cells (DC) are central to the development of acute graft-versus-host disease (GVHD) following allogeneic hematopoietic stem cell transplantation (alloHSCT). We hypothesized that DC activation status determines the severity of GVHD and that activated DC may be detected in the circulation prior to clinical presentation of GVHD.

METHODS

Following transplant, blood samples were obtained twice weekly from alloHSCT patients. Myeloid (CD11c+) and plasmacytoid (CD123hi) DC were enumerated by flow cytometry, and activated myeloid DC were identified using the CMRF-44 monoclonal antibody.

RESULTS

Of 40 alloHSCT patients, 26 developed acute GVHD. Severity of GVHD was associated with low total blood DC counts (P=0.007) and with low myeloid and plasmacytoid DC numbers (P=0.015 and 0.003). The CMRF-44 antigen was expressed on blood CD11c+ DC in all cases prior to GVHD onset, whereas of the 14 patients without GVHD, seven had no CMRF-44+ CD11c DC. Patients with CMRF-44+ CD11c+ DC in more than 20% of samples were more likely to subsequently develop acute GVHD (P=0.001, odds ratio=37.1), while patients who developed grade 2-4 GVHD had prior higher percentages of CMRF-44+ CD11c+ DC compared to grade 0-1 GVHD patients (P=0.001). CMRF-44 expression on >7.9% CD11c+ DC predicted for subsequent development of GVHD with a sensitivity of 87.5% and specificity of 79.2%.

CONCLUSIONS

Activation status, as assessed by CMRF-44 antigen expression, of blood CD11c+ DC is highly associated with acute GVHD and these cells may be targets for therapeutic intervention.

Inhibition of NF-kappa B during human dendritic cell differentiation generates anergy and regulatory T-cell activity for one but not two human leukocyte antigen DR mismatches

We examined the in vitro inhibition of human monocyte-derived dendritic cells (DC) maturation via NF-kappaB blockade on T-cell allostimulation, cytokine production, and regulatory T-cell generation. DC were generated from CD14+ monocytes isolated from peripheral blood using GM-CSF and IL-4 for differentiation and TNF-alpha, IL-1beta, and PGE2 as maturational stimuli with or without the NF-kappaB inhibitors, BAY 11-7082 (BAY-DC) or Aspirin (ASA-DC). Stimulator and responder cells were one versus two HLA-DR mismatched in direct versus indirect presentation assays. Both BAY-DC and ASA-DC expressed high levels of HLA-DR and CD86 but always expressed less CD40 compared with controls. Some experiments showed slightly lower levels of CD80. Both BAY- and ASA-allogeneic DC and autologous alloantigen pulsed DC were weaker stimulators of T cells (by MLR) compared with controls, and there was reduced IL-2 and IFN-gamma production by T cells stimulated with BAY-DC or ASA-DC (by ELISPOT) (more marked results were always observed with ASA-treated DC). In addition, NF-kappaB blockade of DC maturation caused the generation of T cells with regulatory function (T regs) but only when T cells were stimulated by either allogeneic (direct presentation) or alloantigen pulsed autologous DC (indirect presentation) with one HLA-DR mismatch and not with two HLA-DR mismatches (either direct or indirect presentation). However, the T regs generated from these ASA-DC showed similar FoxP3 mRNA expression to those from nontreated DC. Extension of this study to human organ transplantation suggests potential therapies using one DR-matched NF-kappaB blocked DC to help generate clinical tolerance.

A novel approach to detect donor/recipent immune responses between HLA-identical pairs

Renal transplant rejection and graft versus host reactions between HLA genetically-identical sibling (HLAgi) donor/recipient (D/R) pairs are thought to result from minor histocompatibility antigen (mHAg) disparities. We have compared two methods of measuring HLAgi D/R T lymphocyte responses to "matured" dendritic cells: 1.) a modified Cylex assay of CD4(+) ATP levels (MLDC-ATP) versus 2.) (3)H-thymidine uptake (MLDC-(3)H). The MLDC-ATP kinetics peaked at 48 hours versus the MLDC-(3)H at 7 days, and appeared more sensitive. We tested HLAgi (normal) volunteer siblings (NLs), and D/R sibling pairs before and after renal transplantation (pre-Tx and post-Tx). The overall frequencies of positive responses in the MLDC-ATP for HLAgi NLs, pre-Tx, and post-Tx D/R pairs were 63%, 50%, and 42%, respectively. The percentage with reciprocal responses was 37.5%, 20%, and 22.22%, respectively. In one set of three HLAgi (NLs) siblings (two males and one female), there was a nongender-associated differential response. There was no MLDC correlation with class I MHC-associated mHAg (SSP) incompatibility, nor could some MLDC positive reactive pairs theoretically process the necessary HLA-class I restriction molecules for presentation of known (nanomeric) mHAg peptides. Speculatively, the MLDC reflects class II MHC-restricted mHAg reactions (not yet definable), with possible effects of other polymorphic (nonhistocompatibility) immune response genes, and thereby may be a useful measurement of CD4(+) T-cell HLAgi transplantation immunity.

Cooperative induction of a tolerogenic dendritic cell phenotype by cytokines secreted by pancreatic carcinoma cells

Ag presentation by dendritic cells (DC) is essential to effective antitumor T cell responses in cancer patients. Depending on their origin, maturation state, and the ambient cytokine milieu, DC can differentiate into distinct subpopulations, which preferentially either induce Th1 cell activation (CD11c+,CD123- myeloid DC (MDC)) or immunosuppressive T cell development (CD11c-,CD123+ plasmacytoid DC (PDC)). The present study was undertaken to characterize the effects of pancreatic carcinoma cell-derived cytokines on immature monocyte-derived DC (iMo-DC) in vitro and in vivo. Medium conditioned by human pancreatic carcinoma cells inhibited iMo-DC proliferation, expression of costimulatory molecules (CD80 and CD40) and of HLA-DR, and functional activity as assessed by MLR and IL-12p70 production. iMo-DC generated from pancreatic carcinoma patients in advanced stages of the disease similarly showed decreased levels of HLA-DR expression and reduced ability to stimulate MLR in response to CD40L and IFN-gamma. Moreover, in tumor-patient peripheral blood, the ratio of MDC to PDC cells was lower than in healthy controls due to reduced numbers of MDC CD11c+ cells. Importantly, rather than a single cytokine, a combination of tumor-derived cytokines was responsible for these effects; these were primarily TGF-beta, IL-10, and IL-6, but not vascular endothelial growth factor. In summary, we have identified an array of pancreatic carcinoma-derived cytokines that cooperatively affect iMo-DC activation in a manner consistent with ineffective antitumor immune responses.

G-CSF increases the number of peripheral blood dendritic cells CD16+ and modifies the expression of the costimulatory molecule CD86+

Dendritic cells (DC) play a key role in initiating immune reactions after allogeneic stem cell transplantation. The two main peripheral blood DC populations are myeloid (DC1) and lymphoplasmacytoid (DC2). A new subset of myeloid DC, expressing CD16, has been identified. We analyzed the number and CD86 expression of DC subsets in peripheral blood of 18 healthy donors, before and after granulocyte colony-stimulating factor (G-CSF) and in the inoculum of allogeneic peripheral blood transplants (allo-PBT; n=100) and allogeneic bone marrow transplants (allo-BMT; n=22). Granulocyte colony-stimulating factor administration increased the median number of DC1 (P=0.0007), of DC2 (P<0.0001) and of DC CD16+ (P=0.0001). Granulocyte colony-stimulating factor administration was also associated with a significant decrease of CD86 expression on DC1 (P=0.0003) and with a trend for an increase on DC CD16+ (P=0.07). Recipients of allo-PBT received similar quantities of DC1 and higher doses of DC2 and DC CD16+ than recipients of allo-BMT (P=0.5; P=0.0001; P<0.0001, respectively). Granulocyte colony-stimulating factor modifies the number of DC in peripheral blood and the expression of the costimulatory molecule CD86. This resulted in a different composition of DC2 and especially of DC CD16+ in the harvests, which might explain some of the differences observed in allogeneic reactions after allo-PBT with respect to allo-BMT.

Vesiculated alpha-tocopheryl succinate enhances the anti-tumor effect of dendritic cell vaccines

Alpha tocopheryl succinate (alpha-TOS) is a non-toxic vitamin E analog under study for its anti-cancer properties. In an earlier study, we showed that alpha-TOS, when used in combination with non-matured dendritic cells (nmDC) to treat pre-established tumors, acts as an effective adjuvant. In this study, we have used vesiculated alpha-TOS (Valpha-TOS), a more soluble form of alpha-TOS that is relevant for clinical use, in combination with dendritic cells to treat pre-established murine tumors. We demonstrate that Valpha-TOS kills tumor cells in vitro and inhibits the growth of pre-established murine lung carcinoma (3LLD122) as effectively as alpha-TOS. The combination of Valpha-TOS plus non-matured or TNF-alpha-matured DC is more effective at inhibiting the growth of established tumors than Valpha-TOS alone. We also observed that Valpha-TOS induces expression of heat shock proteins in tumor cells and that co-incubation of non-matured DC with lysate derived from Valpha-TOS-treated tumor cells leads to DC maturation evidenced by up-regulation of co-stimulatory molecules and secretion of IL-12p70. This study therefore demonstrates the immunomodulatory properties of Valpha-TOS that may account for its adjuvant effect when combined with DC vaccines to treat established tumors.

Effective osteosarcoma cytolysis using cytokine-induced killer cells pre-inoculated with tumor RNA-pulsed dendritic cells

Osteosarcoma with distant metastases at late stage has posed a challenge for novel therapeutic modalities. The application of cytokine-induced killer (CIK) cells to osteosarcoma constitutes a promising strategy. This approach had been studied in multiple myeloma and breast cancers, where CIK cells exhibited specific cytotoxicity toward malignant cells while sparing wild-type tissues. However, the consistency of CIK cell-induced anti-tumor cytotoxicity has not been thoroughly examined. We investigated whether autologous CIK cells could effectively induce cytolysis of cultured osteosarcoma cells. In addition to the observed CIK cell-induced osteosarcoma cytolysis, the pre-incubation of CIK cells with autologous dendritic cells pulsed with tumor's total RNA further enhanced the tumor cytolysis to greater than 6-fold. The anti-tumor cytolysis was optimized in complete autologous setting, and was attenuated with allogeneic components. The advantage of the co-culture with RNA-pulsed DC was lost when high CIK cell density was employed for anti-tumor cytotoxic assay, but was maintained in purified CD3(+)CD56(+) cells isolated from the CIK cells. This finding implied that CIK cells at limited cell density could induce effective osteosarcoma cytolysis with an aid from tumor antigen presentation on dendritic cell surface.

Chemo-Immunotherapy of Breast Cancer Using Vesiculated α-Tocopheryl Succinate in Combination With Dendritic Cell Vaccination

In this study, we evaluated the efficacy of vesiculated alpha-tocopheryl succinate (Valpha-TOS) in combination with non-antigen pulsed, nonmatured dendritic cells (nmDC) to treat pre-established tumors of the highly metastatic murine mammary cancer cell line 4T1. We demonstrated that Valpha-TOS in combination with non-antigen pulsed nmDC significantly inhibits the growth of established tumors in vivo and prolongs survival of treated mice. In addition, when initiated after resection of the established primary tumor, the combination treatment dramatically inhibits residual metastatic disease. The clinical response achieved with the combination therapy was correlated with increased interferon-gamma and interleukin-4 (IL-4) production by splenic lymphocytes and draining lymph node cells. Interestingly, when used in combination with Valpha-TOS, nmDC were as effective as tumor necrosis factor-alpha matured DC at inhibiting the growth of pre-established tumors. Valpha-TOS-induced cellular factors collected by high-speed centrifugation of supernatant from Valpha-TOS-treated tumor cells caused maturation of DC as evidenced by the up-regulation of co-stimulatory molecules and secretion of IL-12p70. These results demonstrate the potential usefulness of Valpha-TOS + DC chemo-immunotherapy in treating established primary mammary tumors as well as residual metastatic disease.

Campath-1H does not alter bone marrow cell regulatory function

We have previously reported in laboratory volunteers (in vitro) and renal transplant recipients (ex vivo) that bone marrow cells (BMC) are potent downregulators of the immune response. Also, the use of alemtuzumab (Campath-1H, C1H) for immunodepletion is associated with the most potent lasting effects yet seen on T-cell immunity in renal transplantation. We questioned whether the administration of C1H to kidney allograft recipients of donor bone marrow cell (DBMC) infusions would lead to stronger or weaker immunoregulatory effects. Human BMC depleted of T cells (nT-BMC) were either untreated or treated with C1H and rabbit complement and compared for their ability to downregulate autologous or allogeneic T-cell responses and to generate T regulatory (T reg) cells. The proliferative responses to anti-CD3 monoclonal antibody of T cells derived from cocultures with C1H-treated or untreated autologous nT-BMC were equally suppressed, i.e., an equivalent alteration in CD3 complex signaling, not regained by the addition of interleukin 2. Adenosine triphosphate levels were also markedly reduced in T cells both from C1H-treated and untreated nT-BMC cocultures. The ability of C1H-treated or untreated nT-BMC to suppress autologous T-cell cytotoxic function was also equivalent, with a marked, but equivalent, capacity to induce CD4/CD25(high) T regs from CD3(+) cells, which effectively downregulated cytotoxic T cells. To mimic the clinical infusion of DBMC into (allogeneic) recipients, peripheral blood mononuclear cells were also cultured with allogeneic C1H-treated and untreated nT-BMC. T cells derived from these cultures secondarily stimulated with the same-donor mature antigen-presenting cells exhibited suppressed cytotoxicity by 85% and 54%, respectively. These in vitro studies suggest that C1H does not abrogate BMC immunoregulation and thus may allow its lympho-depleting effect to be synergistic.