Proliferation Of Dendritic Cells Research Articles

Inhibition of Rgs10 Expression Prevents Immune Cell Infiltration in Bacteria-induced Inflammatory Lesions and Osteoclast-mediated Bone Destruction.

Regulator of G-protein Signaling 10 (Rgs10) plays an important function in osteoclast differentiation. However, the role of Rgs10 in immune cells and inflammatory responses, which activate osteoclasts in inflammatory lesions, such as bacteria-induced periodontal disease lesions, remains largely unknown. In this study, we used an adeno-associated virus (AAV-) mediated RNAi (AAV-shRNA-Rgs10) knockdown approach to study Rgs10's function in immune cells and osteoclasts in bacteria-induced inflammatory lesions in a mouse model of periodontal disease. We found that AAV-shRNA-Rgs10 mediated Rgs10 knockdown impaired osteoclastogenesis and osteoclast-mediated bone resorption, in vitro and in vivo. Interestingly, local injection of AAV-shRNA-Rgs10 into the periodontal tissues in the bacteria-induced inflammatory lesion greatly decreased the number of dendritic cells, T-cells and osteoclasts, and protected the periodontal tissues from local inflammatory damage and bone destruction. Importantly, AAV-mediated Rgs10 knockdown also reduced local expression of osteoclast markers and pro-inflammatory cytokines. Our results demonstrate that AAV-shRNA-Rgs10 knockdown in periodontal disease tissues can prevent bone resorption and inflammation simultaneously. Our data indicate that Rgs10 may regulate dendritic cell proliferation and maturation, as well as the subsequent stimulation of T-cell proliferation and maturation, and osteoclast differentiation and activation. Our study suggests that AAV-shRNA-Rgs10 can be useful as a therapeutic treatment of periodontal disease.

Blastic plasmacytoid dendritic cell neoplasm: clinical features in 90 patients

Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a rare disease characterized by malignant proliferation of a contingent blastic plasmacytoid dendritic cell. This rare entity is recognized mostly by cutaneous spreading, or not having a leukaemic component. The prognosis is very poor. To study a large cohort of 90 patients with BPDCN, to define additional symptoms to form a correct diagnosis earlier, and to manage such patients accordingly. We retrospectively reviewed BPDCN cases registered in the French Study Group on Cutaneous Lymphoma database between November 1995 and January 2012. Ninety patients were studied. Demographic data, clinical presentation, initial staging and outcome were recorded. The group contained 62 male and 28 female patients (sex ratio 2·2). Their ages ranged from 8 to 103 years at the time of diagnosis (mean 67·2 years). Three major different clinical presentations were identified. Sixty-six patients (73%) presented with nodular lesions only, 11 patients (12%) with 'bruise-like' patches and 13 (14%) with disseminated lesions (patches and nodules). Mucosal lesions were seen in five patients (6%). The median survival in patients with BPDCN was 12 months. We here distinguish three different clinical presentations of BPDCN. A nodular pattern is a more common feature than the originally reported 'bruise-like' pattern. Despite the fact that BPDCN may initially appear as a localized skin tumour, aggressive management including allogeneic bone marrow transplantation should be considered immediately, as it is currently the only option associated with long-term survival.

Use of Cpg Oligonucleotides for Cancer Immunotherapy and Their Effect on Immunity in the Tumor Microenvironment

William Coley was the first physician to employ immunotherapy for patients with cancer [1]. His strategy was based on his clinical observation of cancers regressing after the tumor site became infected with streptococci. This convinced Coley that bacteria could be used to treat cancer. He therefore injected heat-killed bacteria directly into the tumor masses of his patients. This killed bacterial preparation, known as ‘Coley’s toxin’, led to tumor regression in some patients [1]. The antitumor activity of Coley’s toxin was sub sequently attributed to the presence of endotoxin in the preparation. However, the observation concerning tumor regression involved Streptococcus infection: a Gram-positive organism that does not produce endotoxin. More recent studies suggest that other/additional bacterial components, including bacterial DNA, have the capacity to trigger the innate immune system and may well have contributed to the observed responses. In this context, Tokunaga et al. found that BCG lysate slowed the growth of tumors and identified bacterial DNA as the underlying component of the lysate responsible for that response [2]. Krieg et al. then reported on the ability of unmethylated CpG motifs, present at high frequencies in bacterial but not mammalian DNA, to stimulate the immune system [3]. Akira et al. demonstrated that CpG DNA and synthetic oligonucleotides (ODNs) expressing unmethylated CpG motifs were acting on immune cells that expressed Toll-like receptor 9 (TLR9) [4]. Binding of CpG DNA to TLR9 initiated an immuno stimulatory cascade culminating in the maturation, differentiation and/or proliferation of lymphocytes, dendritic cells, NK cells, monocytes and macrophages. Many subsequent reports verified that CpG ODNs could induce the production of cytokines and chemokines that supported a proinflammatory (IL-1,

Langerhans cell histiocytosis in childhood – Review, symptoms in the oral cavity, differential diagnosis and report of two cases

BackgroundLangerhans cell histiocytosis is a rare disease characterized by monoclonal proliferation and migration of special dendritic cells. This disease primarily affects bones, but occurs less frequently in other organ systems or may manifest as a multisystem disease. Case reportsExtraoral and intraoral symptoms of Langerhans cell histiocytosis are described in a 13-month-old female and a 5-month-old male infant.Dermatitis was found on the scalp, abdomen, flexures and in intertrigineous areas in both patients. The intraoral examination of the 13-month-old infant showed premature eruption of all maxillary deciduous molars, loosening and significant damage of periodontal tissues (gingivitis with bleeding, swelling of palatal mucosa, periodontal pockets) resembling severe periodontitis.In the oral cavity of the 5-month-old predentate infant bilateral swellings of maxillary alveolar mucosa with deep ulcerations were seen.The oral and skin symptoms in both infants were indications for biopsy. Langerhans cell histiocytosis was confirmed histologically and immunohistochemically. ConclusionOral findings in Langerhans cell histiocytosis may be the only clinical symptom of the disease; therefore the role of dentists in establishing diagnosis is very important.

T-lymphoblastic proliferation and florid multifocal follicular dendritic cell proliferation occurring in hyaline-vascular Castleman disease in a patient with a possible familial predisposition

Hyaline-vascular Castleman disease (HVCD) often presents as unicentric disease which is usually cured by surgical resection. Here, we report a case of a 23-year-old man with HVCD in the mediastinum, in which an apparently indolent T-lymphoblastic proliferation and extensive organoid proliferation of follicular dendritic cells were also present. The patient had no systemic involvement and no further disease at follow-up. In addition, there is a possible unique family history of HVCD. This case highlights an interesting combination of elements, mostly likely benign in nature.

Indeterminate cell histiocytosis with naïve cells

Histiocytoses are a heterogeneous group of disorders characterized by proliferation and accumulation of cells of mononuclear-macrophage system and dendritic cells. Histiocytoses are categorized according to the cell of origin into Langerhans cell histiocytosis (LCH), Non Langerhans cell histiocytoses and indeterminate cell histiocytosis (ICH). ICH is an extraordinary rare neoplastic dendritic cell disorder that has poorly understood histogenesis and pathogenesis. It is characterized by a proliferation of dendritic cells, which mimic Langerhans cells immunophenotypically (positive for CD1a and S-100 protein), but lack Birbeck granules characteristic of Langerhans cells. Twenty-four year-old Egyptian male was presented with reddish brown chest wall nodule. Clinical, histopathological, immunohistochemical and ultrastructure features are typical for ICH. He was in a good state without any evidence of recurrence or metastasis after 24 months follow up. Peculiar histopathological features were detected in the present case. Many unidentified cells with Hematoxylin & Eosin Langerhans like features showed negative staining for S-100, CD1a, Langerin and CD68. In absence of cellular atypia and mitosis, the infiltrating cells showed epidermotropism that was reported once in ICH as well as neural and perineural invasion that were not previously reported. Therefore we prefer using a tentatively designated diagnosis; dendritic cell tumor, not otherwise specified or newly proposed diagnosis (Indeterminate cell histocytosis with naïve cells) for the present case.

Blockade of PD-1/PD-L1 immune checkpoint during DC vaccination induces potent protective immunity against breast cancer in hu-SCID mice

Immune checkpoints, such as the PD-1/PD-L1 pathway, negatively interfere in the efficiency of dendritic cell (DC) vaccination in cancer immunotherapy. In this study, we demonstrated that the blockade of PD-L1 signaling could promote DC maturation, proliferation, and IL-12 secretion, augment DC primed T cell response and reverse tumor cell dampened T cell impairment. Blockade of PD-L1 signaling during DC vaccination showed better therapeutic effects than classic DC vaccination by preventing tumor growth and prolonging survival times in a breast tumor-bearing hu-SCID model. Taken together, suppressing immune checkpoints during DC vaccination might be a more efficient strategy for cancer therapy.

Langerhans Cell Histiocytosis Presenting as a Unifocal Eosinophilic Granuloma in the Body of the Mandible: A Rare Report

ABSTRACT Introduction Langerhans cell histiocytosis (LCH) is a relatively rare and unique benign disease characterized by an abnormal proliferation of immature dendritic cells which usually affects children and young adults. Jaws are involved in less than 10% of children with the disease. Objective To add on to the literature one more case of this rare and unique disease which accounts for less than 1% of all bone tumors and also to discuss its oral manifestation and management. Design Case report Setting Private maxillofacial surgery institute, Kolkata, West Bengal. Patient A 2 years and 8 months old male child with solitary swelling over the lower left jaw since one and half months. Lesion was fixed to underlying bone and there was an expansion of buccal cortical plate at the body of mandible. Results Enucleation of the lesion performed after assessing history, clinical and radiological dertails and also considering patient's age. Postoperative biopsy result came as LCH presenting as a unifocal eosinophil granuloma. Appropriate surgical intervention resulted in a dramatic improvement in patient's clinical condition. At present, patient is disease-free and asymptomatic. Conclusion Surgical enucleation or curettage is a preferred treatment option for maxillary and mandibular lesion. Potential for the unifocal disease to become multifocal should not be underestimated as the disease can be unpredictable. We recommend long-term follow-up due to uncertainty of the disease.

Aeroallergen Challenge Promotes Dendritic Cell Proliferation in the Airways

Aeroallergen provocation induces the rapid accumulation of CD11c(+)MHC class II (MHC II)(+) dendritic cells (DCs) in the lungs, which is driven by an increased recruitment of blood-derived DC precursors. Recent data show, however, that well-differentiated DCs proliferate in situ in various tissues. This may also contribute to their allergen-induced expansion; therefore, we studied DC proliferation in the airways of mice in the steady state and after local aeroallergen provocation. Confocal whole-mount microscopy was used to visualize proliferating DCs in different microanatomical compartments of the lung. We demonstrate that in the steady state, CD11c(+)MHC II(+) DCs proliferate in both the epithelial and subepithelial layers of the airway mucosa as well as in the lung parenchyma. A 1-h pulse of the nucleotide 5-ethynyl-2'-deoxyuridine was sufficient to label 5% of DCs in both layers of the airway mucosa. On the level of whole-lung tissue, 3-5% of both CD11b(+) and CD11b(-) DC populations and 0.3% of CD11c(+)MHC II(low) lung macrophages incorporated 5-ethynyl-2'-deoxyuridine. Aeroallergen provocation caused a 3-fold increase in the frequency of locally proliferating DCs in the airway mucosa. This increase in mucosal DC proliferation was later followed by an elevation in the number of DCs. The recruitment of monocyte-derived inflammatory DCs contributed to the increasing number of DCs in the lung parenchyma, but not in the airway mucosa. We conclude that local proliferation significantly contributes to airway DC homeostasis in the steady state and that it is the major mechanism underlying the expansion of the mucosal epithelial/subepithelial DC network in allergic inflammation.

FMS-related tyrosine kinase 3 ligand (Flt3L)/CD135 axis in rheumatoid arthritis

IntroductionThe FMS-related tyrosine kinase 3 ligand (Flt3L)/CD135 axis plays a fundamental role in proliferation and differentiation of dendritic cells (DCs). As DCs play an important role in rheumatoid arthritis (RA) immunopathology we studied in detail the Flt3L/CD135 axis in RA patients.MethodsThe levels of Flt3L in (paired) serum and synovial fluid (SF) were quantified by enzyme-link immunosorbent assay (ELISA). Expression of Flt3L and CD135 in paired peripheral blood mononuclear cells (PBMCs) and synovial fluid mononuclear cells (SFMCs) was quantified by fluorescence-activated cell sorting (FACS). The expression of Flt3L, CD135 and TNF-Converting Enzyme (TACE) in synovial tissues (STs) and in vitro polarized macrophages and monocyte-derived DCs (Mo-DCs) was assessed by quantitative PCR (qPCR). CD135 ST expression was evaluated by immunohistochemistry and TACE ST expression was assessed by immunofluorescence. Flt3L serum levels were assessed in RA patients treated with oral prednisolone or adalimumab.ResultsFlt3L levels in RA serum, SF and ST were significantly elevated compared to gout patients and healthy individuals (HI). RA SF monocytes, natural killer cells and DCs expressed high levels of Flt3L and CD135 compared to HI. RA ST CD68+ and CD163+ macrophages, CD55+ fibroblast-like synoviocytes (FLS), CD31+ endothelial cells or infiltrating monocytes and CD19+ B cells co-expressed TACE. IFN-γ-differentiated macrophages expressed higher levels of Flt3L compared to other polarized macrophages. Importantly, Flt3L serum levels were reduced by effective therapy.ConclusionsThe Flt3L/CD135 axis is active in RA patients and is responsive to both prednisolone and adalimumab treatment. Conceivably, this ligand receptor pair represents a novel therapeutic target.

Attenuation of the Adaptive Immune Response in Rhesus Macaques Infected with Simian Varicella Virus Lacking Open Reading Frame 61

Varicella zoster virus (VZV) is a neurotropic alphaherpesvirus that causes chickenpox during primary infection and establishes latency in sensory ganglia. Infection of rhesus macaques (RM) with the homologous simian varicella virus (SVV) recapitulates hallmarks of VZV infection. We have shown that an antisense transcript of SVV open reading frame 61 (ORF61), a viral transactivator, was detected most frequently in latently infected RM sensory ganglia. In this study, we compared disease progression, viral replication, immune response, and the establishment of latency following intrabronchial infection with a recombinant SVV lacking ORF61 (SVVΔORF61) to those following infection with wild-type (WT) SVV. Varicella severity and viral latency within sensory ganglia were comparable in RMs infected with SVVΔORF61 and WT SVV. In contrast, viral loads, B and T cell responses, and plasma inflammatory cytokine levels were decreased in RMs infected with SVVΔORF61. To investigate the mechanisms underlying the reduced adaptive immune response, we compared acute SVV gene expression, frequency and proliferation of dendritic cell (DC) subsets, and the expression of innate antiviral genes in bronchoalveolar lavage (BAL) samples. The abundance of SVV transcripts in all kinetic classes was significantly decreased in RMs infected with SVVΔORF61. In addition, we detected a higher frequency and proliferation of plasmacytoid dendritic cells in BAL fluid at 3 days postinfection in RMs infected with SVVΔORF61, which was accompanied by a slight increase in type I interferon gene expression. Taken together, our data suggest that ORF61 plays an important role in orchestrating viral gene expression in vivo and interferes with the host antiviral interferon response.

Histiocytose langerhansienne osseuse multifocale : intérêt de la scintigraphie osseuse planaire

Langerhans cell histiocytosis is a disease of the reticuloendothelial system characterized by a clonal proliferation of dendritic cells of Langerhans. This is a rare disease that primarily affects children and young adults. It can take many forms, from a single eosinophilic granuloma to widespread lesions involving multisystem life-threatening. Bone involvement is the most common, it can be uni- or multifocal. We report a case of multifocal bone Langerhans cell histiocytosis, revealed in a child aged 3 years and touched his left temporal bone and right femur. The bone scintigraphy has found a third location in right scapular. The outcome was favorable after chemotherapy. The bone lesions are characterized by lytic lesions and are responsible for pain, swelling and fractures. All the imaging techniques (radiographs, CT, and MRI) contribute to the formation of the diagnosis. Bone scintigraphy is a very sensitive examination that allows the initial staging and follow-up on treatment of skeletal manifestations.

Synergistic Effect of Flt3L and Rapamycin On Immune Tolerance Induction Via Plasmacytoid Dendritic Cells and Treg.

Abstract 2209In vivo induction and expansion of Treg is a powerful tool to limit unwanted immune responses and promote tolerance. For example, we have been successful inducing tolerance to factors VIII and FIX in hemophilic mice when the coagulation factor antigen was administered with the mTOR inhibitor rapamycin (J Thromb Haemost 7:1523 and 9:1524, Front Microbiol 2:244). Rapamycin, a macrocyclic triene antibiotic, is an immunosuppressant used to avoid transplant rejection. It suppresses the mTOR1 (and upon prolonged exposure also mTOR2) signaling pathway. Importantly, while mTOR blockage results in deletion of Teff, Treg can be induced and expanded because they are able to utilize alternative (STAT) signaling pathways. Others have shown that existing Treg can be expanded in vivo upon administration of Fms-like tyrosine kinase ligand-3 (Flt3L), a cytokine that drives generation of dendritic cells (DC) from hematopoietic progenitor cells and DC proliferation. This link between DC homeostasis and Treg is evident from the low Treg numbers found in Flt3L-deficient mice and from prevention of graft vs host disease upon treatment with Flt3L. This raises the question of whether a combined approach of rapamycin administration and Flt3L-induced DC generation would result in an optimal immune tolerance protocol. Interestingly, it has been reported that rapamycin blocks Flt3L-induced differentiation of progenitor cells into DC, indicating that Flt3L signaling in DC occurs through the mTOR pathway. However, we find in mice transgenic for an ovalbumin-specific CD4+ T cell receptor (but deficient in recombinase activating gene, rag-2) that ova peptide antigen administration results in substantially enhanced deletion of Teff and in induction of CD4+CD25+FoxP3+CD62L+GITR+ Treg when combined with these two drugs. This was accomplished by repeated administration (twice per week) of a cocktail of the 3 components. Antigen plus either drug causes Teff deletion, while rapamycin is required for Treg induction (which is further enhanced by Flt3L). Antigen, rapamycin, and Flt3L all impact changes in the numbers and frequencies of DC subsets in the spleen during the regimen. The combination all 3 components most potently directs a substantial (3–5 fold, P<0.001) increase in CD11cloPDCA+ plasmacytoid DC numbers (but not of conventional CD11chiPDCA− DCs). While pDCs are known to provide innate anti-viral responses, they also play an important role in immune tolerance. Consequently, when pDC were partially depleted with anti-PDCA, Treg induction was significantly impaired. Furthermore, the protocol caused an increase in the frequency of Indoleamine-pyrrole 2,3-dioxygenase (IDO)-expressing pDCs (which is known to activate resting Treg for suppressor activity). Finally, FLt3L-induced expansion of Treg (but not of DCs) is less effective in GITR-L −/− mice. Combined, these data demonstrate that i) Flt3L and rapamycin can be used synergistically for induction of T cell tolerance, ii) pDCs can be expanded within a rapamycin regimen, iii) and Fl3tL-induced pDC expansion facilitates Treg induction, which is partially dependent on GITR-L (a co-stimulatory molecule primarily expressed by pDCs that promotes cross talk to Treg by engagement of the GITR receptor). In order to establish relevance of this protocol for treatment of disease, we intravenously injected a F.VIII protein/rapamycin/Flt3L cocktail into hemophilia A mice (C57BL6/129 F8e16 −/−) twice per week for 1 month. Subsequently, mice received 1 month of factor replacement therapy (1 IU human FVIII, IV, once per week). Control mice without prior immune modulatory regiment or that received non-specific immune suppression (rapamycin and Flt3L only) formed high-titer inhibitors against FVIII (70–80 BU), which was significantly suppressed to ∼10 BU (P<0.001, n=5 per group). Importantly, inhibitor titers were only mildly reduced (to ∼40 BU) when Flt3L was omitted from the tolerogenic cocktail, thereby confirming the synergistic effect of flt3L and rapamycin in tolerance induction. This approach combines expansion of regulatory antigen presenting and T cells and should be of broad relevance for cell and organ transplantation as well as for treatment of inherited protein deficiencies and of autoimmune diseases. Disclosures:No relevant conflicts of interest to declare.

Specific Skin Lesions in Chronic Myelomonocytic Leukemia

Chronic myelomonocytic leukemia (CMML) is a rare clonal hematopoietic disorder that can also involve the skin. The histopathology of these skin lesions is not clearly defined, and few data are available in the literature. To better understand tumoral skin involvements in CMML we carried out an extensive, retrospective clinicopathologic study of 42 cases selected from the database of the French Study Group of Cutaneous Lymphomas. On the basis of clinical data, morphology, and phenotype we identified 4 clinicopathologic profiles representing 4 distinct groups. The first group comprised myelomonocytic cell tumors (n=18), exhibiting a proliferation of granulocytic or monocytic blast cells, which were CD68 and/or MPO positive but negative for dendritic cell markers. The second group comprised mature plasmacytoid dendritic cell tumors (n=16), denoted by a proliferation of mature plasmacytoid dendritic cells, which were CD123, TCL1, and CD303 positive but CD56, CD1a, and S100 negative. The third group comprised blastic plasmacytoid dendritic cell tumors (n=4), characterized by a proliferation of monomorphous medium-sized blast cells, which were CD4, CD56, CD123, TCL1 positive but CD1a and S100 negative. The fourth group consisted of a putatively novel category of tumor that we named blastic indeterminate dendritic cell tumors (n=4), distinguished by a proliferation of large blast cells that not only exhibited monocytic markers but also the dendritic markers CD1a and S100. These 4 groups showed distinctive outcomes. Finally, we showed, by fluorescence in situ hybridization analysis, a clonal link between bone marrow disease and skin lesions in 4 patients. Herein, we have described a novel scheme for pathologists and physicians to handle specific lesions in CMML, which correspond to a spectrum of myelomonocytic and dendritic cell proliferations with different outcomes. A minimal panel of immunohistochemical markers including CD68, CD1a, S100, Langerin, and CD123 is necessary to make the correct classification in this spectrum of cutaneous CMML tumors, in which dendritic cell lineage plays an important role.

Cross-priming for antitumor CTL induced by soluble Ag + polyI:C depends on the TICAM-1 pathway in mouse CD11c+/CD8α+ dendritic cells

PolyI:C is a nucleotide pattern molecule that induces cross-presentation of foreign Ag in myeloid dendritic cells (DC) and MHC Class I-dependent proliferation of cytotoxic T lymphocytes (CTL). DC (BM or spleen CD8α+) have sensors for dsRNA including polyI:C to signal facilitating cross-presentation. Endosomal TLR3 and cytoplasmic RIG-I/MDA5 are reportedly responsible for polyI:C sensing and presumed to deliver signal for cross-presentation via TICAM-1 (TRIF) and IPS-1 (MAVS, Cardif, VISA) adaptors, respectively. In fact, when tumor-associated Ag (TAA) was simultaneously taken up with polyI:C in DC, the DC cross-primed CTL specific to the TAA in a syngenic mouse model. Here we tested which of the TICAM-1 or IPS-1 pathway participate in cross-presentation of tumor-associated soluble Ag and retardation of tumor growth in the setting with a syngeneic tumor implant system, EG7/C57BL6, and exogenously challenged soluble Ag (EG7 lysate) and polyI:C. When EG7 lysate and polyI:C were subcutaneously injected in tumor-bearing mice, EG7 tumor growth retardation was observed in wild-type and to a lesser extent IPS-1−/− mice, but not TICAM-1−/− mice. IRF-3/7 were essential but IPS-1 and type I IFN were minimally involved in the polyI:C-mediated CTL proliferation. Although both TICAM-1 and IPS-1 contributed to CD86/CD40 upregulation in CD8α+ DC, H2Kb-SL8 tetramer and OT-1 proliferation assays indicated that OVA-recognizing CD8 T cells predominantly proliferated in vivo through TICAM-1 and CD8α+ DC is crucial in ex vivo analysis. Ultimately, tumor regresses > 8 d post polyI:C administration. The results infer that soluble tumor Ag induces tumor growth retardation, i.e., therapeutic potential, if the TICAM-1 signal coincidentally occurs in CD8α+ DC around the tumor.

Tumorous proliferations of plasmacytoid dendritic cells and Langerhans cells associated with acute myeloid leukaemia

Proliferation of plasmacytoid dendritic cells (PDCs) occurs in both reactive lymphoid hyperplasia and myeloproliferative disorders, especially chronic myelomonocytic leukaemia. PDCs in the former appear reactive, but in the latter are reported to be clonally related to the underlying myeloid neoplasm. Langerhans cells (LCs), another type of dendritic cell, also proliferate in both reactive dermatoses and, rarely, myeloproliferative disorders, such as acute leukaemia. We report a rare case of tumorous proliferation of PDCs and LCs in the systemic lymph nodes in a 55-year-old man with acute myeloid leukaemia. A microsatellite instability assay showed identical patterns of short tandem repeats in both microdissected PDC and LC components, along with blood blasts. We hypothesize that the combined proliferations of PDCs and LCs derive from the same haematopoietic stem cells, but that they differentiate divergently under the effect of different microenvironments.

Synergistical toll-like receptors activated dendritic cells induce antitumor effects against carcinoembryonic antigen-expressing colon cancer

Dendritic cell (DC)-based cancer vaccine represents a promising immunotherapy against cancer. There has been recent evidence which have suggested that toll-like receptor (TLR) ligands may be critical for DC preparation; this was usually omitted in the past. Our study is designed to investigate if the vaccination of synergistical toll-like receptors activated DCs can induce more potent cytotoxic T Lymphocytes (CTL) responses and antitumor activity in carcinoembryonic antigen (CEA) transgenic mouse tumor models. We involved combination of TLR3 and TLR7/8 ligands in culture protocol of DCs. The DCs' surface molecules expression, IL-12 secretion and proliferation capacity of lymphocytes were tested. We also investigate the CTL activity against MC38-CEA colon tumor cells and the prophylactic and therapeutic effects of DC vaccination in subcutaneous mouse colon tumor models. Compared with conventionally generated DCs, we showed synergistic TLR-activated DCs exhibited higher surface molecule expression, significantly higher secretion of IL-12 and more potent proliferating capacity of lymphocytes. Synergistic TLR-activated DCs were also able to induce lymphocytes possessing the specific cytotoxicity against MC38-CEA cells in vitro. Vaccination with CEA epitope pulsed TLR-activated DCs elicited antigen-specific preventive effect on MC38-CEA tumors, but failed to cure the tumor-bearing mice, that may be due to the suboptimal epitope selected and host immunosuppression. Our results have proved that combined activation of TLRs can lead to better maturation status of DCs and also induce more effective antitumor immune responses against colon cancer, suggesting this may be a potential strategy to develop more powerful DC cancer vaccines.

E11. The tumour microenvironment in breast cancer

Tumours are aberrant organs that contain host cells and non-cellular components in addition to the cancer cells [1]. The tumour microenvironment consists of extracellular matrix (ECM) components, fibroblasts, adipocytes, cells of the vascular system, cells of the immune system, growth and differentiation factors, chemokines, cytokines and metabolites. The cancer cells themselves have a major influence on the local environment. The composition of the microenvironment varies with tumour stage and influences functions of the cancer and stromal cells. The stromal components may have tumour inhibiting or promoting functions, or both, depending on the context. Indeed, a breast cancer stroma-derived gene expression signature is associated significantly with prognosis [2]. Carcinoma-associated fibroblasts (CAFs) stimulate cancer cell growth, inflammation, angiogenesis and invasion and share characteristics with embryonic fibroblasts or mesenchymal progenitors. Such activated fibroblasts are largely responsible for tumour-associated changes in the ECM, which are caused by increased synthesis and additional post-translational modifications of ECM molecules and by increased remodelling of ECM proteins by matrix metalloproteinases (MMPs) [3]. For example, increased biosynthesis and remodelling of the fibrillar collagen type I is a consistent feature of tumours and is necessary for angiogenesis [4]. The architecture of fibrillar collagen also changes: Whereas collagen fibres are orientated in parallel to normal epithelial cells, in tumours the fibres are mostly perpendicular to the tumour border. This altered architecture of the collagen fibres enables cells to migrate along the collagen fibres, promoting cell invasion. Fibronectin is alternatively spliced in tumours, leading to expression of developmental isoforms. These changes in the ECM result in increased striffness in tumours compared to normal tissues. Thus tumours can be detected as hard nodules distinct from the normal surrounding tissue. Recent research indicates that the relative stiffness of a tissue has major effects on cellular functions: as the tension of non-malignant, mammary epithelial cells approaches that of tumours, these normal cells disorganize and initiate invasive programs. Moreover, collagen cross-linking produces ECM stiffening that together with oncogenes promote invasive behavior. Immune-cell infiltrates are present in most, if not all, solid tumours. This indicates that the genetic events that lead to cancer also trigger immune responses [5]. Indeed, oncogene activation hijacks the immune and inflammation-based program nodes for tissue remodeling and regeneration. The most abundant infiltrating cells are myeloid cells that regulate metastasis and angiogenesis, in addition to down-regulating the immune response against the cancer cells. Tumour-associated macrophages (TAMs) resemble M2 macrophages, which promote tumour growth, invasion, metastasis and angiogenesis, and suppress cytotoxic T cell activity against tumours by releasing cytokines, growth factors, matrixdegrading enzymes and angiogenic factors. Accumulation of TAMs is associated with poor prognosis. The so-called myeloid-derived suppressor cells (MDSCs), which consist of immature and activated neutrophils and monocyte/macrophages, accumulate systemically, in the bone marrow, spleen, and peripheral blood, and at the invasive edge of tumours with increasing tumour progression. MDSCs also may promote angiogenesis and promote resistance to anti-angiogenic therapy. They also influence the anti-tumour immune response by producing reactive oxygen species that inhibit proliferation and function of dendritic cells, natural killer cells, B cells and cytotoxic T lymphocytes and by inducing regulatory T cells (TRegs) [6,7]. Tumour blood vessels are disorganised. Instead of clear arterioles, capillaries and venules, the tumour vasculature is irregular, dilated, and can have dead ends, with loosely associated perivascular cells. These changes result in abnormal blood flow and increased vascular permeability. The onset of tumour angiogenesis, known as the ‘angiogenic switch’, ensures tumour growth, but can occur at different tumour progression stages. Although cancer cells can secrete pro-angiogenic factors, the tumourinfiltrating myeloid-derived cells are an important source. These cells are recruited to tumours by factors secreted by hypoxic cancer cells, including vascular endothelial growth factor (VEGF) and stroma-derived factor 1/ chemokine CXC ligand 12 (SDF1/CXCL12). Myeloidderived cells (including monocytes, macrophages, neutrophils, mast cells, immature dendritic cells and MDSCs), which are often located in close proximity to tumour blood vessels, are implicated in tumour angiogenesis. Specialized microenvironments within tumours, often referred to as ‘niches’, confer distinct functions to the

Langerhans Cell Histiocytosis Presenting with Headache and Sellar Mass in an Adult

Introduction Langerhans Cell Histiocytosis (LCH) is a rare disease characterized by aberrant proliferation of a specific dendritic (Langerhans) cell belonging to the monocyte macrophage system. 1 These cells can infiltrate virtually any organ without inducing dysfunction. 2 LCH is encountered more often in children, with a peak age range of 1-3 years and an incidence of 3-5 cases per million per year and a male to female ratio of 2:1. 3 LCH is rare in adults and the incidence may be underestimated due to the fact that many cases likely go undiagnosed. In order of decreasing frequency, the presenting symptoms are skin rash, dyspnea or tachypnea, polyuria and polydipsia, bone pain, lymphadenopathy, weight loss, fever, gingival hypertrophy, ataxia, and memory problems. 4 Regarding the endocrine system, LCH has a particular predilection for involvement of the hypothalamo–pituitary axis (HPA), leading to diabetes insipidus (DI) in up to 50% of cases. In a recent analysis, DI was the most common and permanent consequence of LCH, occurring in 24% of patients. 5 Other endocrine deficiencies can develop in up to 20% of patients. 5,6 Endocrine manifestations include DI followed by growth hormone deficiency with a median latency of about one year, followed by gonadotropin deficiency with a median latency of about seven years from the diagnosis of DI. ACTH and TSH deficiency also have been described. 7

Is Serum IL-17A a Useful Systemic Biomarker in Patients With Langerhans Cell Histiocytosis?

To the editor: In a recent article in Molecular Therapy, Hogarty1 elucidated the still unresolved issue regarding the role of interleukin-17A (IL-17A) in the pathogenesis of Langerhans cell histiocytosis (LCH) and whether serum IL-17A could be used as a systemic biomarker of the disease. In the same article, it was stated that the “IL-17A issue,” beyond its academic interest, has definite therapeutic implications, given that IL-17A-targeted treatments are now in preclinical development for LCH. Therefore, clear conclusions are urgently required that can be obtained only through collective work. LCH is a rare disease of obscure etiology, involving single or multiple systems of the human body. Although all lesions share common histopathological features, LCH has an unpredictable clinical course ranging from spontaneous resolution to disseminated disease, compromising vital functions with occasionally fatal consequences. It is characterized by the clonal accumulation and/or proliferation of specific dendritic cells that resemble the normal epidermal Langerhans cell; however, there is ongoing debate over whether the origin of the disease is immunological or neoplastic. IL-17, also known as IL-17A and cytotoxic T lymphocyte–associated antigen 8 (CTLA-8), is a T cell–specific proinflammatory cytokine involved in chronic inflammatory states presenting with granuloma formation and also in bone resorption through RANKL induction in osteoblasts.2 Histological features of LCH resembling granulomas, as well as osteolytic bone lesions of the disease, provide indications of a possible central role of IL-17A in LCH pathogenesis. Recently, Coury et al. implicated IL-17A, favoring the immune etiology of LCH.3 These authors demonstrated increased serum IL-17A concentrations in 13 subjects (2 adults) at various stages of LCH (12 patients with multiple-system disease; all patients had received several chemoimmunotherapy treatments).3 They also suggested that IL-17A was originating from the dendritic cells rather than the T cells, and, although total serum IL-17A concentrations did not correlate with the activity of the disease, serum IL-17A-dependent fusion activity did correlate with the activity of LCH.3 On the basis of these findings, a potential IL-17A-targeted therapy was proposed as a future therapeutic approach in LCH, whereas IL-17A appeared as a possible biomarker to monitor disease activity. Therefore, and according to these findings, IL-17A-targeted treatments, which are currently in phase I and phase II trials for other inflammatory conditions, are also considered in LCH.1 However, another research group was unable to identify any IL-17A messenger RNA expression in 12 lesions from 10 pediatric patients with LCH.4 Peters et al. studied plasma samples from 26 LCH patients with active disease and 46 pediatric control subjects and reported IL-17A at background levels in LCH patients at concentrations consistent with controls in two different standard enzyme-linked immunosorbent assay (ELISA) kits. In addition, IL-17A concentrations of both patients and controls were highly variable according to the development ELISA kit utilized in the study by Coury et al.3 Moreover, the principal antibody employed by Coury et al. cross-reacted with protein lysate from LCH lesions. Therefore, it was suggested that the lack of identifiable IL-17A transcripts or protein expression in the lesions precludes the possibility of lesional IL-17A production and subsequent autocrine and/or paracrine action.1 LCH is rarer in adults than in children, with an estimated annual incidence of 1 case per 560,000 inhabitants, and it is therefore regarded as an “orphan disease.”5 In our recent study of 25 adults with LCH at various disease stages who had previously received a variety of treatments, we found decreased bone mineral density as well as decreased bone turnover in those treated with chemotherapy or glucocorticoids or both.6 In the same patients, we have now measured serum IL-17A concentrations in duplicates (standard deviation and coefficient of variation values of 5.9 and 4.7%, respectively) using one of the three commercial kits employed in the study by Peters et al. (Human IL-17 Quantikine ELISA kit, D1700; RD Mann-Whitney test, P = 0.144), as well as no association between LCH activity and serum levels of IL-17A. These differences remained nonsignificant after exclusion of the two apparently healthy controls with high IL-17 values (outliers, Figure 1) (patients 154 ± 19 pg/ml vs. controls, 115 ± 10 pg/ml; Mann-Whitney test, P = 0.072). Figure 1 Interleukin-17A levels in patients and controls. From our findings, it seems that serum IL-17A is not ubiquitously increased among LCH patients with active disease. Multicenter studies with large numbers of patients are needed to define whether several parameters such as age (adults vs. children), disease extension and involvement, and treatment administered can influence IL-17A. Our findings are in agreement with those from the previous groups that failed to demonstrate a correlation between IL-17A concentrations and disease activity, and they suggest that serum IL-17A cannot serve as a biomarker to differentiate patients with LCH and active disease or indicate those who might benefit from an IL-17A-targeted therapeutic approach.