Granulocyte-Macrophage Colony-Stimulating Factor in Combination With Chemoradiation for Recurrent or Metastatic Cervical Cancer

Recurrent or metastatic cervical cancer carries a bleak prognosis and presents a formidable challenge in terms of treatment. Granulocyte-macrophage colony-stimulating factor (GM-CSF) increases the body's immune response by enhancing antigen presentation, which has been rarely reported in recurrent or metastatic cervical cancer. A 44-year-old woman presented to the hospital with vaginal bleeding four years after radical hysterectomy for stage IB2 squamous cell carcinoma (SCC) of the cervix (grade II-III). Gynecological examination and imaging revealed a vaginal mass, and the biopsy confirmed the recurrence of grade III SCC. The patient was treated with chemoradiation (CRT) combined with immunoadjuvant GM-CSF and achieved complete remission and a progression-free survival of two years.

Vitamin D3 mitigates autoimmune inflammation caused by activation of myeloid dendritic cells in SLE

Systemic lupus erythematosus (SLE) is an autoimmune disease in which defective T cells, immune complex deposition and other immune system alterations contribute to pathological changes of multiple organ systems. The vitamin D metabolite c is a critical immunomodulator playing pivotal roles in the immune system. Epidemiological evidence indicates that vitamin D deficiency is correlated with the severity of SLE. Our aim is to investigate the effects of 1,25(OH)2D3 (VitD3) on the activation of myeloid dendritic cells (mDCs) by autologous DNA-containing immune complex (DNA-ICs), and the effects of VitD3 on immune system balance during SLE. We purified DNA-ICs from the serum of SLE patients and isolated mDCs from normal subjects. In vitro studies showed that DNA-ICs were internalized and consumed by mDCs. VitD3 blocked the effects of DNA-ICs on RelB, IL-10 and TNF-α in mDCs. Further analysis indicated that DNA-ICs stimulated histone acetylation in the RelB promoter region, which was inhibited by VitD3. Knockdown of the histone deacetylase 3 gene (HDAC3) blocked these VitD3-mediated effects. Co-culture of mDCs and CD4+ T cells showed that VitD3 inhibited multiple processes mediated by DNA-ICs, including proliferation, downregulation of IL-10, TGF-β and upregulation of TNF-α. Moreover, VitD3 could also reverse the effects of DNA-IC-induced imbalance of CD4+  CD127-  Foxp3+ T cells and CD4+  IL17+ T cells. Taken together, our results indicated that autologous DNA-ICs stimulate the activation of mDCs in the pathogenesis of SLE, and VitD3 inhibits this stimulatory effects of DNA-ICs by negative transcriptional regulation of RelB gene and maintaining the Treg/Th17 immune cell balance. These results suggest that vitamin D may have therapeutic value for the treatment of SLE.

GM-CSF, Flt3-L and IL-4 affect viability and function of conventional dendritic cell types 1 and 2

Conventional type 1 dendritic cells (cDC1) and conventional type 2 dendritic cells (cDC2) have attracted increasing attention as alternatives to monocyte-derived dendritic cells (moDCs) in cancer immunotherapy. Use of cDCs for therapy has been hindered by their low numbers in peripheral blood. In the present study, we found that extensive spontaneous apoptosis and cDC death in culture within 24hrs represent an additional challenge. Different media conditions that maintain cDC viability and function were investigated. CD141+ cDC1 and CD1c+ cDC2 were isolated from healthy blood donor buffy coats. Low viabilities were found with CellGenix DC, RPMI-1640, and X-VIVO 15 standard culture media and with several supplements at 24hrs and 48hrs. Among multiple factors it was found that GM-CSF improved both cDC1 and cDC2 viability, whereas Flt3-L and IL-4 only increased viability of cDC1 and cDC2, respectively. Combinations of these three cytokines improved viability of both cDCs further, both at 24hrs and 48hrs time points. Although these cytokines have been extensively investigated for their role in myeloid cell differentiation, and are also used clinically, their effects on mature cDCs remain incompletely known, in particular effects on pro-inflammatory or tolerogenic cDC features. HLA-DR, CD80, CD83, CD86, PD-L1 and PD-L2 cDC membrane expressions were relatively little affected by GM-CSF, IL-4 and Flt3-L cytokine supplements compared to the strong induction following Toll-like receptor (TLR) stimulation for 24hrs. With minor exceptions the three cytokines appeared to be permissive to the TLR-induced marker expression. Allogeneic mixed leukocyte reaction showed that the cytokines promoted T-cell proliferation and revealed a potential to boost both Th1 and Th2 polarizing cytokines. GM-CSF and Flt3-L and their combination improved the capability of cDC1 for dextran uptake, while in cDC2, dextran capture was improved by GM-CSF. The data suggest that GM-CSF, IL-4 and Flt3-L and combinations might be beneficial for DC viability and function in vitro. Limited viability of cDCs could be a confounding variable experimentally and in immunotherapy.

Cooperation between cGAS and RIG-I sensing pathways enables improved innate recognition of HIV-1 by myeloid dendritic cells in elite controllers

Introduction

Spontaneous control of HIV-1 replication in the absence of anti-retroviral therapy (ART) naturally occurs in a small proportion of HIV-1-infected individuals known as elite controllers (EC), likely as a result of improved innate and adaptive immune mechanisms. Previous studies suggest that enhanced cytosolic immune recognition of HIV-1 reverse transcripts in conventional dendritic cells (mDC) from EC enables effective induction of antiviral effector T cell responses. However, the specific molecular circuits responsible for such improved innate recognition of HIV-1 in mDC from these individuals remain unknown.

Results and methods

Here, we identified a subpopulation of EC whose mDC displayed higher baseline abilities to respond to intracellular HIV-1 dsDNA stimulation. A computational analysis of transcriptional signatures from such high responder EC, combined with functional studies, suggested cytosolic recognition of HIV-1 dsDNA by cGAS, combined with sensing of viral mRNA by RIG-I after polymerase III-mediated HIV-1 DNA transcription.

Discussion

Together, our work identifies collaborative networks of innate sensing pathways that enhance cell-intrinsic abilities of mDC to induce antiviral innate responses against HIV-1; these observations might be useful for the therapeutic induction of effective antiviral immune responses.

Increased CD69+CCR7+ circulating activated T cells and STAT3 expression in cutaneous lupus erythematosus patients recalcitrant to antimalarials

BACKGROUND

Antimalarials are first-line systemic therapy for cutaneous lupus erythematosus (CLE). While some patients unresponsive to hydroxychloroquine (HCQ) alone benefit from the addition of quinacrine (QC), a subset of patients is refractory to both antimalarials.

METHODS

We classified CLE patients as HCQ-responders, HCQ+QC-responders, or HCQ+QC-nonresponders to compare immune profiles. Immunohistochemistry, immunofluorescence, and qRT-PCR were used to characterize inflammatory cells and cytokines in lesional skin.

RESULTS

Immunohistochemistry showed that CD69⁺ T cells were higher in HCQ+QC-nonresponders compared to HCQ- and HCQ+QC-responders (p < 0.05). Immunofluorescence further identified these cells as CD69+CCR7+ circulating activated T cells. Myeloid dendritic cells were significantly higher in HCQ+QC-responders compared to both HCQ-responders and HCQ+QC-nonresponders. Plasmacytoid dendritic cells were significantly increased in HCQ-responders compared to HCQ- and HCQ+QC-nonresponders. No differences were found in the number of autoreactive T cells, MAC387+ cells, and neutrophils among the groups. CLASI scores of the HCQ+QC-nonresponder group positively correlated with CD69+CCR7+ circulating activated T cells (r = 0.6335, p < 0.05) and MAC387+ cells (r = 0.5726, p < 0.05). IL-17 protein expression was higher in HCQ+QC-responders compared to HCQ-responders or HCQ+QC-nonresponders, while IL-22 protein expression did not differ. mRNA expression demonstrated increased STAT3 expression in a subset of HCQ+QC-nonresponders.

CONCLUSION

An increased number of CD69+CCR7+ circulating activated T cells and a strong correlation with CLASI scores in the HCQ+QC-nonresponders suggest these cells are involved in antimalarial-refractory skin disease. STAT3 is also increased in HCQ+QC-nonresponders and may also be a potential target for antimalarial-refractory skin disease.

Comprehensive immune cell profiling depicts an early immune response associated with severe coronavirus disease 2019 in cancer patients

Recent studies have highlighted multiple immune perturbations related to severe acute respiratory syndrome coronavirus 2 infection-associated respiratory disease [coronavirus disease 2019 (COVID-19)]. Some of them were associated with immunopathogenesis of severe COVID-19. However, reports on immunological indicators of severe COVID-19 in the early phase of infection in patients with comorbidities such as cancer are scarce. We prospectively studied about 200 immune response parameters, including a comprehensive immune-cell profile, inflammatory cytokines and other parameters, in 95 patients with COVID-19 (37 cancer patients without active disease and intensive chemo/immunotherapy, 58 patients without cancer) and 21 healthy donors. Of 95 patients, 41 had severe disease, and the remaining 54 were categorized as having a nonsevere disease. We evaluated the association of immune response parameters with severe COVID-19. By principal component analysis, three immune signatures defining characteristic immune responses in COVID-19 patients were found. Immune cell perturbations, in particular, decreased levels of circulating dendritic cells (DCs) along with reduced levels of CD4 T-cell subsets such as regulatory T cells (T_regs ), type 1 T helper (Th1) and Th9; additionally, relative expansion of effector natural killer (NK) cells were significantly associated with severe COVID-19. Compared with patients without cancer, the levels of terminal effector CD4 T cells, T_regs , Th9, effector NK cells, B cells, intermediate-type monocytes and myeloid DCs were significantly lower in cancer patients with mild and severe COVID-19. We concluded that severely depleted circulating myeloid DCs and helper T subsets in the initial phase of infection were strongly associated with severe COVID-19 independent of age, type of comorbidity and other parameters. Thus, our study describes the early immune response associated with severe COVID-19 in cancer patients without intensive chemo/immunotherapy.

Type I interferon receptor-independent interferon-α induction upon infection with a variety of negative-strand RNA viruses

Type I interferons (IFNs) are a first line of defence against viral infections. Upon infection, a first small wave of early type I IFN, mainly IFN-β and particularly IFN-α₄, are induced and bind to the type I IFN receptor (IFNAR) to amplify the IFN response. It was shown for several viruses that robust type I IFN responses require this positive feedback loop via the IFNAR. Recently, we showed that infection of IFNAR knockout mice with the orthomyxovirus Thogoto virus lacking the ML open reading frame (THOV(ML-)) results in the expression of unexpected high amounts of type I IFN. To investigate if IFNAR-independent IFN responses are unique for THOV(ML-), we performed infection experiments with several negative-strand RNA viruses using different routes and dosages for infection. A variety of these viruses induced type I IFN responses IFNAR-independently when using the intraperitoneal (i.p.) route for infection. In vitro studies demonstrated that myeloid dendritic cells (mDC) are capable of producing IFNAR-independent IFN-α responses that are dependent on the expression of the adaptor protein mitochondrial antiviral-signalling protein (MAVS) whereas pDC where entirely depending on the IFNAR feedback loop in vitro. Thus, depending on dose and route of infection, the IFNAR feedback loop is not strictly necessary for robust type I IFN expression and an IFNAR-independent type I IFN production might be the rule rather than the exception for infections with numerous negative-strand RNA viruses.

Upregulated Expression of Profilin1 on Dendritic Cells in Patients With Severe Aplastic Anemia

Severe aplastic anemia (SAA) is a life-threatening form of bone marrow failure that is associated with very high mortality. Dendritic cells (DCs) are antigen presenting cells (APCs) with powerful movement ability, which is an important factor affecting immune function. The expression of profilin1 (Pfn1) plays an important role in the regulation of cell movement ability. We detected the expression of Pfn1 mRNA in the bone marrow (BM) myeloid dendritic cells (mDCs) from patients with SAA using RT-PCR. Next, we examined Pfn1 expression on mDCs using flow cytometry (FCM). We also assessed the relationship between Pfn1 expression and cytokine levels. Our data showed increased Pfn1 mRNA expression in patients with SAA. The expression of Pfn1 in BM mDCs increased in SAA patients. The expression of Pfn1 on mDCs and cytokines (TNF-α and IFN-γ) were positively correlated in the serum of untreated patients with SAA. Taken together, we found that the expression of Pfn1 on mDCs of SAA patients increased, which may affect the function of mDCs. Profilin 1 may be involved in the immunopathogenesis of SAA.

CCL13 is upregulated in alopecia areata lesions and is correlated with disease severity

Alopecia areata (AA) is a multi-factors disease characterized by non-scarring hair loss. AA could be classified into three main clinical phenotypes including patchy type AA (AAP), alopecia totalis (AT) and alopecia universalis (AU) based on the severity and areas of hair loss. Recent studies suggested immunological factor was critical in AA, but the precise aetiology and pathogenesis of AA still need exploration. In the work, we screened two gene expression profiles (GSE45512 and GSE68801) from Gene Expression Omnibus (GEO). Based on the two data sets, 10 upregulated genes and 107 downregulated genes in AA skin biopsies were identified. CCL13, as one of the remarkably upregulated genes, was found to have potential biological functions in aberrant immune response of AA according to the GO and KEGG analyses. The PPI network showed CCL13 was associated with multiple immune-related genes. The expression of CCL13 was increased depending on the severity of disease in AA patients. Cytotoxic lymphocytes, T cells and myeloid dendritic cells accumulated remarkably in scalp tissue depending on the severity of AA, and CCL13 was significantly correlated to cytotoxic lymphocytes, T cells and myeloid dendritic cells in AA patients. Our RT-PCR and ELISA results found CCL13 was upregulated in skin biopsy and serum of AA patients, and the immunohistochemistry (IHC) detection showed CCL13 was expressed by both the hair follicle epithelium and infiltrating immune cells. In conclusion, the upregulated of CCL13 and subsequent immune cell infiltration was related to AA, which could be a promising target for diagnosis and therapy in AA patients.

Upregulated expression of leukocyte immunoglobulin-like receptor A3 in patients with severe aplastic anemia

Severe aplastic anemia (SAA) is a rare and potentially life-threatening disease characterized by pancytopenia and bone marrow (BM) hypoplasia. In a previous study by our group, increased expression of leukocyte immunoglobulin-like receptors A (LILRA), LILRA3 in myeloid dendritic cells (mDCs) and LILRA5 in CD34⁺ cells in SAA was detected using proteomics techniques, highlighting their potential role in disease pathogenesis. In the present study, the expression of LILRA1-6 mRNA was assessed in the BM mononuclear cells of patients with SAA using reverse transcription-quantitative (RT-q)PCR. The expression of homogenic LILRA3 and LILRA5 isoform on mDCs, as well as CD34⁺, CD3⁺CD8⁺, CD19⁺ and CD14⁺ cells, was detected using flow cytometry. mDCs were then induced, cultured and sorted. The expression of LILRA3 was confirmed using RT-qPCR and western blot analyses. The serum levels of soluble LILRA3 were measured using ELISA. Furthermore, the relationship between LILRA3 expression and disease severity was assessed. The results indicated increased LILRA3 mRNA expression in patients with SAA. The percentage of LILRA3⁺ in BM mDCs and CD34⁺ cells was increased. Compared with controls, the relative LILRA3 mRNA expression and the relative protein intensity were highly increased in SAA mDCs. The serum LILRA3 levels in patients with SAA were also increased. The proportion of LILRA3⁺CD11C⁺ human leukocyte antigen (HLA)-DR⁺/CD11C⁺HLA-DR⁺ cells was positively correlated with the ratio of LILRA3⁺CD34⁺/CD34⁺ cells and the expression of LILRA3 mRNA. Taken together, the expression of LILRA3 on mDCs of patients with SAA was increased, which may affect the function of mDCs. LILRA3 may have a significant role in the immune pathogenesis of SAA.

Myeloid and plasmacytoid dendritic cell combined vaccines loaded with heat-treated tumor cell lysates enhance antitumor activity in murine lung cancer

The present study aimed to investigate the efficacy of a myeloid dendritic cell (mDCs) and plasmacytoid (p)DC combined vaccine loaded with heat-treated cancer cell lysates against lung cancer cells. The mDCs and pDCs were selected using magnetic bead sorting. Antigen loading was performed by adding heat-treated Lewis lung cancer cell lysates to mDC, pDC or mDC+pDC (1:1). Surface expression of CD80, CD86, CD40 and major histocompatibility complex (MHC)-II molecules were determined using flow cytometry, and the secretion of cytokines IL-12, IL-6 and TNF-α were assessed using ELISA assays. The effect of the mDC and pDC vaccine on cytotoxic T lymphocytes (CTLs) against tumor cells was investigated. Tumor-bearing nude mice were intravenously injected with the mDC and pDC combined vaccine. Tumor tissues were collected for hematoxylin and eosin and TUNEL staining. Loading with tumor cell lysate significantly upregulated the surface expression of costimulatory molecules MHC-II on DCs and enhanced secretions of IL-6, IL-12 and TNF-α by DCs. In addition, the tumor cell lysate-loaded mDC and pDC combined vaccine significantly promoted lymphocyte proliferation and enhanced CTL-mediated cytotoxicity against Lewis lung cancer cells compared with mDC or pDC treatment alone. Furthermore, intravenous injection of the mDC and pDC combined vaccine into tumor-bearing nude mice significantly inhibited subcutaneous tumor growth and induced necrosis and apoptosis within the tumor tissue. Overall, the pDC and mDC combination vaccine loaded with heat-treated Lewis lung cancer cell lysate had a synergistic effect on the induction of T lymphocyte proliferation and antitumor efficacy, which may be associated with the upregulation of co-stimulatory molecules and cytokine secretions.

Intratumoral Combinatorial Administration of CD1c (BDCA-1)+ Myeloid Dendritic Cells Plus Ipilimumab and Avelumab in Combination with Intravenous Low-Dose Nivolumab in Patients with Advanced Solid Tumors: A Phase IB Clinical Trial

Intratumoral (IT) myeloid dendritic cells (myDCs) play a pivotal role in re-licensing antitumor cytotoxic T lymphocytes. IT injection of the IgG₁ monoclonal antibodies ipilimumab and avelumab may induce antibody-dependent cellular cytotoxicity, thereby enhancing the release of tumor antigens that can be captured and processed by CD1c (BDCA-1)⁺ myDCs. Patients with advanced solid tumors after standard care were eligible for IT injections of ≥1 lesion with ipilimumab (10 mg) and avelumab (40 mg) and intravenous (IV) nivolumab (10 mg) on day 1, followed by IT injection of autologous CD1c (BDCA-1)⁺ myDCs on day 2. IT/IV administration of ipilimumab, avelumab, and nivolumab was repeated bi-weekly. Primary objectives were safety and feasibility. Nine patients were treated with a median of 21 × 10⁶ CD1c (BDCA-1)⁺ myDCs, and a median of 4 IT/IV administrations of ipilimumab, avelumab, and nivolumab. The treatment was safe with mainly injection-site reactions, but also immune-related pneumonitis (n = 2), colitis (n = 1), and bullous pemphigoid (n = 1). The best response was a durable partial response in a patient with stage IV melanoma who previously progressed on checkpoint inhibitors. Our combinatorial therapeutic approach, including IT injection of CD1c (BDCA-1)⁺ myDCs, is feasible and safe, and it resulted in encouraging signs of antitumor activity in patients with advanced solid tumors.

Isolated Cutaneous Langerhans Cell Histiocytosis Presenting in an Adult Male

Langerhans cell histiocytosis (LCH) is an infrequent clonal proliferative disorder of myeloid dendritic cells. It has a wide variety of cutaneous manifestations and retains the possibility of systemic implications. Because LCH is predominantly a disease of childhood, there are well-established clinical definitions, as well as guidelines regarding workup and treatment, in the context of pediatric disease. Here we present a case of isolated cutaneous LCH in an adult male, followed by a discussion of our diagnostic plan and treatment course. The patient exhibited a small, excoriated, yellow papule on his inferior forehead during a skin examination. The specimen underwent tangential shave biopsy; histopathologic evaluation with appropriate immunohistochemical staining confirmed a diagnosis of cutaneous LCH. After thorough investigation via serologic and imaging diagnostics, we confirmed isolated cutaneous disease. The patient underwent wide local excision (WLE) with no evidence of recurrence. It is crucial to appropriately screen all patients diagnosed with cutaneous LCH for internal organ involvement. The authors aim to highlight the need for further investigations to ultimately dictate standardized management and treatment for isolated cutaneous LCH in the adult population.

Effects of myeloid and plasmacytoid dendritic cells on ILC2s in patients with allergic rhinitis

BACKGROUND

Group 2 innate lymphoid cells (ILC2s) were reported to serve a critical role in allergic diseases. Myeloid dendritic cells (mDCs) and plasmacytoid DCs (pDCs) play significant roles in allergic immune response. However, effects of DCs on ILC2s in allergic diseases, especially for patients with allergic rhinitis (AR), remain unclear.

OBJECTIVE

We sought to address the roles of mDCs and pDCs in regulating ILC2 function in AR.

METHODS

mDCs and pDCs were cocultured with human PBMCs isolated from patients with AR or ILC2s to measure soluble or intracellular T_H2 cytokines, transcription factors, signaling pathways in ILC2s, and the following mechanisms were further investigated. The levels of peripheral IL-33⁺mDCs, pDCs, and ILC2s were studied in patients under an inhaled allergen challenge.

RESULTS

We confirmed the presence of ILC2s, mDCs, and pDCs in the nasal mucosa of patients with AR. Both allogenic and autologous mDCs were found to activate ILC2s from patients with AR to produce T_H2 cytokines, and increase the levels of GATA-3 and signal transducer and activator of transcription signaling pathways, in which IL-33-producing mDCs exerted the major role by binding on ST2 on ILC2s. We further identified high levels of IL-33⁺mDCs and ILC2s in patients with AR under antigen challenge. Activated pDCs inhibited the cytokine production of ILC2s isolated from patients with AR by secretion of IL-6.

CONCLUSIONS

mDCs promote ILC2 function by the IL-33/ST2 pathway, and activation of pDCs suppresses ILC2 function through IL-6 in patients with AR. Our findings provide new understanding of the interplay between DCs and ILC2s in allergic diseases.

Human Miscarriage Is Associated With Dysregulations in Peripheral Blood-Derived Myeloid Dendritic Cell Subsets

Dendritic cells (DC) are critically involved in decisions related to the acceptance or rejection of the foreign fetal antigens by the maternal immune system. However, particularly for human peripheral blood DCs (PBDC), available literature is rather inconsistent and the factors regulating these cells are ill-defined. Here, we investigated the phenotype and functionality of different human PBDC subsets during normal and pathologic pregnancies and studied an involvement of human chorionic gonadotropin (hCG) in PBDC regulation. Peripheral blood samples were obtained from normal pregnant women in all three trimesters, from first trimester miscarriage patients and from healthy non-pregnant women. Samples were analyzed for plasma hCG levels, for regulatory T (Treg) cell numbers, for frequencies of total and mature plasmacytoid (PDC) and myeloid (MDC1 and MDC2) PBDC subsets and for their cytokine secretion. In vitro assays, culturing PDC, MDC1 or MDC2 in the presence of two trophoblast cell lines, placenta explant supernatants or two hCG preparations were performed. The Treg-inducing capability of hCG- or non-hCG-treated stimulated MDC1 was assessed. Total and mature MDC1 and MDC2 frequencies increased during the first and second trimester of normal pregnancy, respectively. Miscarriage was associated with a reduced MDC1 and an increased MDC2 activation profile. PDC were not altered neither during normal pregnancy progression nor during miscarriage. In vitro, the culture of isolated PBDC subsets in the presence of placenta-derived factors impaired the maturation of MDC1 and differentially affected PDC maturation. An inhibitory effect on MDC1 and PDC maturation was also proven for the urine-derived hCG preparation. Finally, we observed a Treg cell elevation during early normal pregnancy that was not present in miscarriages. Stimulated MDC1 induced Treg cells in vitro, however, hCG was not involved in this process. Our findings suggest that during normal pregnancy PBDC subsets are differentially regulated dependent on gestational age. Miscarriage seems to be associated with dysregulations in the myeloid PBDC subsets and with disturbances in Treg cell frequencies. Moreover, our results propose an interdependency between MDC1 and Treg cells during early pregnancy. hCG, although shown to impair MDC1 maturation, does not seem to be a key regulator of PBDC alterations during pregnancy.

Packed Red Blood Cell Transfusion Modulates Myeloid Dendritic Cell Activation and Inflammatory Response In Vitro

Transfusion of packed red blood cells (PRBCs) modulates patients' immune responses and clinical outcomes; however, the underpinning mechanism(s) remain unknown. The potential for PRBC to modulate myeloid dendritic cells (mDC) and blood DC antigen 3 was assessed using an in vitro transfusion model. In parallel, to model processes activated by viral or bacterial infection, toll-like receptor agonists polyinosinic:polycytidylic acid or lipopolysaccharide were added. Exposure to PRBC upregulated expression of CD83 and downregulated CD40 and CD80 on both DC subsets, and it suppressed production of interleukin (IL)-6, IL-8, IL-12, tumor necrosis factor-α, and interferon-gamma-inducible protein-10 by these cells. Similar effects were observed when modeling processes activated by concurrent infection. Furthermore, exposure to PRBC at date of expiry was associated with more pronounced effects in all assays. Our study suggests PRBC have an impact on recipient DC function, which may result in failure to establish an appropriate immune response, particularly in patients with underlying infection.

Resiquimod-Mediated Activation of Plasmacytoid Dendritic Cells Is Amplified in Multiple Sclerosis

Background: Multiple sclerosis (MS) is a chronic inflammatory autoimmune disease of the central nervous system. The cause of multiple sclerosis is unknown but there are several evidences that associate the genetic basis of the disease with environmental causes. An important association between viral infection and development of MS is clearly demonstrated. Viruses have a strong impact on innate immune cells. In particular, myeloid dendritic cells (mDCs) and plasmacytoid dendritic cells (pDCs), are able to respond to viruses and to activate the adaptive immune response. Methods: In this study we mimic viral infection using synthetic single-strand RNA, Resiquimod, and we compared the response of both DC subsets derived from healthy donors and MS patients by characterizing the expression of costimulatory molecules on the DC surface. Results: We found that pDCs from MS patients express higher levels of OX40-L, HLA-DR, and CD86 than healthy donors. Moreover, we found that blood cells from MS patients and healthy donors upon Resiquimod-stimulation are enriched in a subpopulation of pDCs, characterized by a high amount of costimulatory molecules. Conclusion: Overall, these results indicate that activation of pDCs is enhanced in MS, likely due to a latent viral infection, and that costimulatory molecules expressed on pDCs could mediate a protective response against the viral trigger of autoimmunity.

Photodynamic Therapy for Genital Warts Causes Activation of Local Immunity

BACKGROUND

5-aminolevulinic acid photodynamic therapy (PDT) for genital warts is effective, safe, and can prevent recurrence. It is believed that PDT can induce immune responses, but the mechanism is not completely understood.

OBJECTIVES

The objectives of this article are to confirm the effect of PDT for genital warts on local immunity and to investigate the recruitment and significance of immune cells in tissues.

METHODS

Local immune changes in T lymphocytes (CD3+, CD4+, CD8+), plasmacytoid dendritic cells (pDCs) (CD123+), and myeloid dendritic cells (CD1a+) after PDT in patients were evaluated by immunohistochemistry staining. Changes in mRNA levels of IFN-γ, IFN-α, IFN-ß, interferon-stimulated gene 15 kDa (ISG-15), Mx2, Toll-like receptor 9 (TLR9), and interferon regulatory factor 7 (IRF7) were analyzed by real-time quantitative polymerase chain reaction.

RESULTS

At 4 hours after PDT, CD4+ increased, accompanied by increased levels of mRNA expression of IFN-γ, but CD4+ and mRNA expression levels of IFN-γ were decreased at 24 hours after PDT. CD123+ pDCs showed an increasing trend. CD1a+ LCs in the epidermis gradually decreased, and DCs in the epidermis gradually increased. CD3+ infiltrated and migrated to the superficial dermis, but CD8+ did not change significantly after PDT. The mRNA expression levels of IFN-α, IFN-ß, ISG-15, Mx2, TLR9, and IRF7 showed an increasing trend after PDT. As compared with the patients without significantly increased IFN-α and IFN-ß after PDT sessions, patients with significant increases needed fewer sessions of PDT for remission.

CONCLUSIONS

PDT for genital warts can activate T lymphocyte-mediated, DC-related, and pDC-related immunity. The clinical efficacy of PDT for genital warts may be related to the increased levels of IFN-α and IFN-ß after treatment.

Commensal and Pathogenic Bacteria Indirectly Induce IL-22 but Not IFNγ Production From Human Colonic ILC3s via Multiple Mechanisms

Innate lymphoid cells (ILCs) are a diverse family of cells that play critical roles in mucosal immunity. One subset of the ILC family, Group 3 ILCs (ILC3s), has been shown to aid in gut homeostasis through the production of IL-22. IL-22 promotes gut homeostasis through its functional effect on the epithelial barrier. When gut epithelial barrier integrity is compromised, such as in Human Immunodeficiency Virus (HIV) infection and inflammatory bowel disease (IBD), microbes from the gut lumen translocate into the lamina propria, inducing a multitude of potentially pathogenic immune responses. In murine models of bacterial infection, there is evidence that bacteria can induce pro-inflammatory IFNγ production in ILC3s. However, the impact of diverse translocating bacteria, particularly commensal bacteria, in dictating IFNγ versus IL-22 production by human gut ILC3s remains unclear. Here, we utilized an in vitro human lamina propria mononuclear cell (LPMC) model to evaluate ILC3 cytokine production in response to a panel of enteric Gram-positive and Gram-negative commensal and pathogenic bacteria and determined potential mechanisms by which these cytokine responses were induced. The percentages of IL-22-producing ILC3s, but not IFNγ-producing ILC3s, were significantly increased after LPMC exposure to both Gram-positive and Gram-negative commensal or pathogenic bacterial stimuli. Stimulation of IL-22 production from ILC3s was not through direct recognition of bacterial antigen by ILC3s, but rather required the help of accessory cells within the LPMC population. CD11c+ myeloid dendritic cells generated IL-23 and IL-1β in response to enteric bacteria and contributed to ILC3 production of IL-22. Furthermore, ligation of the natural cytotoxicity receptor NKp44 on ILC3s in response to bacteria stimulation also significantly increased the percentage of IL-22-producing ILC3s. Overall, these data demonstrate that human gut microbiota, including commensal bacteria, indirectly modulate colonic ILC3 function to induce IL-22, but additional signals are likely required to induce IFNγ production by colonic ILC3s in the setting of inflammation and microbial translocation.

Functional Impairment of Circulating FcεRI+ Monocytes and Myeloid Dendritic Cells in Hepatocellular Carcinoma and Cholangiocarcinoma Patients

BACKGROUND

Hepatocellular carcinoma (HCC) and cholangiocarcinoma (CCA) represent the most common primary liver malignancies whose outcome is influenced by the immune response.

METHODS

In this study, we have functionally characterized, by flow cytometry, circulating myeloid dendritic cells (mDCs) and FcεRI⁺ monocytes in a group of healthy individuals (n = 10) and in a group of patients with HCC (n = 19) and CCA (n = 8), at the time point of the surgical resection (T0) and once the patient had recovered from surgery (T1). Moreover, we proceeded to a more in depth phenotypic characterization of the FcεRI⁺ monocyte subpopulation.

RESULTS

A significant decrease in the frequency of TNFα producing FcεRI⁺ monocytes and mDCs in HCC and CCA patients when compared to the group of healthy individuals was observed, and a close association between FcεRI⁺ monocytes and mDCs dysfunction was identified. In addition, the phenotypic characteristics of FcεRI⁺ monocytes from healthy individuals strongly suggest that this population drives to mDCs, which matches with the fact that both populations are functionally affected.

CONCLUSIONS

The frequency and the function of circulating mDCs and FcεRI⁺ monocytes are affected in both HCC and CCA patients, and FcεRI⁺ monocytes could represent those fated to become mDCs. © 2019 International Clinical Cytometry Society.

Identification and characterization of dendritic cell subtypes in preserved and cultured cadaveric human corneolimbal tissue on amniotic membrane

PURPOSE

Rejection is the leading cause of failure of limbal allogafts. Resident dendritic cell (DC) maturation plays a critical role in host allosensitization. There are two lineages: myeloid (mDC) and lymphoid (pDC), with different biological properties. The aim was to analyse the distribution of DC subtypes in limbal explant cultures on amniotic membrane (AM), cultivated on either the epithelial or stromal side and to compare the results with directly isolated cells from cadaveric whole corneoscleral tissue divided into specific areas.

METHODS

The expression of CD11c (mDC), CD303/CD123 (pDC) and costimulatory molecules CD80, CD86 and activation markers HLA-DR, CD83 was investigated by flow cytometry. Additionally, the corneal epithelium marker CK12 and ABCB5, a new epithelial stem cell marker, were investigated.

RESULTS

Cells positive for pDC and mDC markers were found in all examined areas, with a nonsignificant prevalence of pDC. In limbal explant cultures on AM, the percentage of pDC and mDC was similar, with no statistically significant difference between cultures on epithelial or stromal sides of AM. However, with ex vivo limbal explant cultivation on AM, the pDC content declined significantly (p < 0.05) and the ABCB5 marker was likewise statistically significantly reduced.

CONCLUSION

This is the first study to characterize the distribution of pDC and mDC subsets in cultured and noncultured human corneolimbal tissue. Additionally, ABCB5 positive cells were identified. These findings might be important for future strategies, allowing preparation of corneolimbal allografts with optimal stem cell content for a longer lasting therapeutic effect.

Expression of selected genes of dendritic and Treg cells in blood and skin of morphea patients treated with UVA1 phototherapy

INTRODUCTION

Morphea is a chronic autoimmune disease characterized by fibrosis of the skin. Dendritic cells (DC) and regulatory T cells (Tregs) play a significant role in development of autoimmune and tolerance mechanisms. The aim of the study was to establish the expression of selected genes of plasmacytoid and myeloid DC, Treg cells, and the microenvironment of cytokines (interleukin-17A (IL-17A), transforming growth factor β (TGF-β)) in blood and skin of morphea patients. In addition, the effect of UVA1 phototherapy on expression of the aforementioned genes was evaluated.

MATERIAL AND METHODS

The study was performed on 15 blood and 10 skin samples from patients with morphea. The evaluation included expression of CLEC4C (C-type lectin domain family 4, member C receptor), Lymphocyte antigen 75 (LY75), Forkhead box p3 (foxp3) transcription factor, IL-17A and TGF-β genes in peripheral blood mononuclear cells (PBMC) and in skin samples both before and after UVA1 phototherapy using real-time polymerase chain reaction.

RESULTS

The study revealed lower expression of CLEC4C before (p = 0.010) and after (p = 0.009) phototherapy and lower expression of IL-17A before (p = 0.038) phototherapy in PBMC of patients with morphea vs. the control group. Expression of CLEC4C in PBMC correlated negatively (rho = -0.90; p = 0.001) with activity of disease after phototherapy. No significant differences were found between expression of analysed genes before and after UVA1 therapy in PBMC and skin of morphea patients.

CONCLUSIONS

The results do not confirm the involvement of analysed subsets of DC and Tregs in UVA1 phototherapy in morphea, but point to CLEC4C as a possible biomarker associated with the disease activity.

Distribution of peripheral dendritic cells in patients with HBV infection or spleen and kidney deficiency

Spleen and kidney deficiency syndrome (SKD), a Traditional Chinese Medicine (TCM) syndrome, is the fundamental mechanisms of TCM. We aim to investigate the distribution of peripheral dendritic cells (DCs) in HBV patients with SKD or non-SKD. Peripheral venous blood from patients with HBV infection and healthy volunteers was collected to extract PBMC, and flow cytometry assay was used to measure the distribution of DCs subsets, including myeloid dendritic cells (mDCs) and plasmacytoid dendritic cells (pDCs). For the number of pDCs, it was higher in control group and non-SKD group, compared with HBV infection group and SKD group, respectively. For the number of mDCs, it was higher in control group and the non-SKD group compared to SKD group, while in control group it was higher than both HBeAg positive group and negative group. The number of pDCs in control group and chronic hepatitis B group were higher than HBVcarrier group, and it was higher in control group than both immune tolerance group and inactive group, while in immune clearance group it was higher than immune tolerance group and inactve group. The number of mDCs in control group and immune clearance group were higher than that of immune tolerance group. There was an obvious correlation between TCM syndromes and immune function in HBV infected patients, the number of pDCs and mDCs of the SKD group was lower than that in non-SKD group. These results provide a new insight into scientific evidence that TCM probably be based.

Monomethyl fumarate treatment impairs maturation of human myeloid dendritic cells and their ability to activate T cells

BACKGROUND

Dimethyl fumarate (DMF) and its active metabolite monomethyl fumarate (MMF) effectively lead to reduction in disease relapses and active magnetic resonance imaging (MRI) lesions. DMF and MMF are known to be effective in modulating T- and B-cell responses; however, their effect on the phenotype and function of human myeloid dendritic cells (mDCs) is not fully understood.

OBJECTIVE

To investigate the role of MMF on human mDCs maturation and function.

METHODS

mDCs from healthy controls were isolated and cultured in vitro with MMF. The effect of MMF on mDC gene expression was determined by polymerase chain reaction (PCR) array after in vitro MMF treatment. The ability of mDCs to activate T cells was assessed by in vitro co-culture system. mDCs from DMF-treated multiple sclerosis (MS) patients were analyzed by flow cytometry and PCR.

RESULTS

MMF treatment induced a less mature phenotype of mDCs with reduced expression of major histocompatibility complex class II (MHC-II), co-stimulatory molecules CD86, CD40, CD83, and expression of nuclear factor κB (NF-κB) subunits RELA and RELB. mDCs from DMF-treated MS patients also showed the same immature phenotype. T cells co-cultured with MMF-treated mDCs showed reduced proliferation with decreased production of interferon gamma (IFN-γ), interleukin-17 (IL-17), and granulocyte-macrophage colony-stimulating factor (GM-CSF) compared to untreated cells.

CONCLUSION

We report that MMF can modulate immune response by affecting human mDC function.

Allergen-induced Changes in Bone Marrow and Airway Dendritic Cells in Subjects with Asthma

RATIONALE

Dendritic cells (DCs) are antigen-presenting cells essential for the initiation of T-cell responses. Allergen inhalation increases the number of airway DCs and the release of epithelial-derived cytokines, such as IL-33 and thymic stromal lymphopoietin (TSLP), that activate DCs.

OBJECTIVES

To examine the effects of inhaled allergen on bone marrow production of DCs and their trafficking into the airways in subjects with allergic asthma, and to examine IL-33 and TSPL receptor expression on DCs.

METHODS

Bone marrow, peripheral blood, bronchoalveolar lavage (BAL), and bronchial biopsies were obtained before and after inhalation of diluent and allergen from subjects with asthma that develop allergen-induced dual responses. Classical DCs (cDCs) were cultured from bone marrow CD34(+) cells. cDC1s, cDC2s, and plasmacytoid DCs were measured in bone marrow aspirates, peripheral blood, and BAL by flow cytometry, and cDCs were quantified in bronchial biopsies by immunofluorescence staining.

MEASUREMENTS AND MAIN RESULTS

Inhaled allergen increased the number of cDCs grown from bone marrow progenitors, and cDCs and plasmacytoid DCs in bone marrow aspirates 24 hours after allergen. Allergen also increased the expression of the TSLP receptor, but not the IL-33 receptor, on bone marrow DCs. Finally, inhaled allergen increased the percentage of cDC1s and cDC2s in BAL but only cDC2s in bronchial tissues.

CONCLUSIONS

Inhaled allergen increases DCs in bone marrow and trafficking of DCs into the airway, which is associated with the development airway inflammation in subjects with allergic asthma. Inhaled allergen challenge also increases expression of TSLP, but not IL-33, receptors on bone marrow DCs.

Airway epithelial cells enhance the immunogenicity of human myeloid dendritic cells under steady state

Dendritic cells (DCs) and airway epithelial cells (AECs) are in close proximity, and AECs secrete factors such as retinoic acid which induce tolerance in DCs at homeostasis. However, the question remains as to how DCs in the lung are able to respond to pathogens in the immunosuppressive environment. Using an in vitro human myeloid DC (mDC)-AEC co-culture system, we demonstrate that AECs induced several gene changes in the mDCs cultured with AECs compared to the mDCs not cultured with AECs. Analysis revealed that several chemokine genes were altered. These chemokine genes could serve to attract neutrophils, natural killer (NK) T as well as T helper type 1 (Th1)/Th2 cells to the airways. Genes priming lipid and major histocompatibility complex (MHC) class II antigen presentation were also up-regulated, along with certain anti-microbial protein genes. In addition, the expression and function of pathogen-sensing Toll-like receptors (TLRs) as well as Nod-like receptors (NLRs) and their downstream signalling molecules were up-regulated in mDCs cultured with AECs. Moreover, murine mucosal DCs from the lung expressed significantly higher levels of TLRs and NLRs compared to peripheral DCs from the spleen. These results indicate that AECs prime mDCs to enhance their immunogenicity, which could be one of the mechanisms that compensates for the immunosuppressive mucosal environment.

Functional Impairment of Murine Dendritic Cell Subsets following Infection with Infective Larval Stage 3 of Brugia malayi

Filarial parasites cause functional impairment of host dendritic cells (DCs). However, the effects of early infection on individual DC subsets are not known. In this study, we infected BALB/c mice with infective stage 3 larvae of the lymphatic filarial parasite Brugia malayi (Bm-L3) and studied the effect on fluorescence-activated cell sorter (FACS)-sorted DC subsets. While myeloid DCs (mDCs) accumulated by day 3 postinfection (p.i.), lymphoid DCs (LDCs) and CD8⁺ plasmacytoid DCs (pDCs) peaked at day 7 p.i. in the spleens and mesenteric lymph nodes (mLNs) of infected mice. Increased tumor necrosis factor alpha (TNF-α) but reduced interleukin 12 (IL-12) and Toll-like receptor 4 (TLR4), -6, and -9 and reciprocal secretion of IL-4 and IL-10 were also observed across all DC subsets. Interestingly, Bm-L3 increased the expression of CD80 and CD86 across all DC subsets but decreased that of major histocompatibility complex class II (MHC-II) on mDCs and pDCs, resulting in their impaired antigen uptake and presentation capacities, but maximally attenuated the T-cell proliferation capacity of only mDCs. Furthermore, Bm-L3 increased phosphorylated p38 (p-p38), but not p-ERK, in mDCs and LDCs but downregulated them in pDCs, along with differential modulation of protein tyrosine phosphatases SHP-1, TCPTP, PTEN, and PTP1B across all DC subsets. Taken together, we report hitherto undocumented effects of early Bm-L3 infection on purified host DC subsets that lead to their functional impairment and attenuated host T-cell response.

Oncolytic measles virus induces tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)-mediated cytotoxicity by human myeloid and plasmacytoid dendritic cells

Attenuated measles virus (MV) is currently being evaluated in clinical trials as an oncolytic therapeutic agent. Originally used for its lytic activity against tumor cells, it is now admitted that the effectiveness of MV also lies in its ability to initiate antitumor immune responses through the activation of dendritic cells (DCs). In this study, we investigated the capacity of oncolytic MV to convert human blood myeloid CD1c⁺ DCs and plasmacytoid DCs (pDCs) into cytotoxic effectors. We found that MV induces the expression of the cytotoxic protein TNF-related apoptosis-inducing ligand (TRAIL) on the surface of DCs. We demonstrate that the secretion of interferon-α (IFN-α) by DCs in response to MV is responsible for this TRAIL expression. Several types of PRRs (pattern recognition receptors) have been implicated in MV genome recognition, including RLRs (RIG-I-like receptors) and TLRs (Toll-like receptors). We showed that CD1c⁺ DCs secrete modest amounts of IFN-α and express TRAIL in an RLR-dependent manner upon exposure to MV. In pDCs, MV is recognized by RLRs and also by TLR7, leading to the secretion of high amounts of IFN-α and TRAIL expression. Finally, we showed that MV-stimulated DCs induce TRAIL-mediated cell death of Jurkat cells, confirming their acquisition of cytotoxic functions. Our results demonstrate that MV can activate cytotoxic myeloid CD1c⁺ DCs and pDCs, which may participate to the antitumor immune response.

Reduced Dendritic Cells Expressing CD200R1 in Children with Inflammatory Bowel Disease: Correlation with Th17 and Regulatory T Cells

Loss of tolerance of the adaptive immune system towards indigenous flora contributes to the development of inflammatory bowel diseases (IBD). Defects in dendritic cell (DC)-mediated innate and adoptive immune responses are conceivable. The aim of this study was to investigate the expression of the inhibitory molecules CD200R1 and their ligand CD200 on DCs, to clarify the role of the DCs in the pathogenesis of IBD. Thirty-seven pediatric IBD patients (23 with Crohn’s disease (CD) and 14 with ulcerative colitis (UC)) with mean age 13.25 ± 2.9 years were included. Fourteen age-matched healthy pediatric volunteers (five males and nine females) served as a control group (HC). The percentage of CD11c⁺ myeloid dendritic cells (mDCs) and CD123⁺ plasmacytoid DCs (pDCs) expressing CD200R1 and CD200 were evaluated in peripheral blood using flow cytometry and were correlated with routine biochemical, serological markers, serum levels of cytokines and with the percentages of circulating regulatory T cells (Treg) and CD4⁺ producing IL-17 (Th17). IBD patients showed a significant decrease in the percentage of pDCs and mDCs expressing CD200R1 compared to that of HC. Patients with UC showed increased expressions of the CD200 molecule on pDCs as compared to HC. DCs expressing CD200R1 were found to be correlated positively with Treg and negatively with TH17 and erythrocyte sedimentation rate (ESR). Our findings suggest that IBD is associated with dysregulation in the CD200R1/CD200 axis and that the decrease in DCs expressing CD200R1 may contribute to the imbalance of Th17 and Treg cells and in the pathogenesis of IBD.

Elevated presence of myeloid dendritic cells in nasal polyps of patients with chronic rhinosinusitis

BACKGROUND

Although chronic rhinosinusitis with nasal polyps (CRSwNP) is characterized by Th2 inflammation, the mechanism underlying the onset and amplification of this inflammation has not been fully elucidated. Dendritic cells (DCs) are major antigen-presenting cells, central inducers of adaptive immunity and critical regulators of many inflammatory diseases. However, the presence of DCs in CRS, especially in nasal polyps (NPs), has not been extensively studied.

OBJECTIVE

The objective of this study was to characterize DC subsets in CRS.

METHODS

We used real-time PCR to assess the expression of mRNA for markers of myeloid DCs (mDCs; CD1c), plasmacytoid DCs (pDCs; CD303) and Langerhans cells (LCs; CD1a, CD207) in uncinate tissue (UT) from controls and patients with CRS as well as in NP. We assayed the presence of DCs by immunohistochemistry and flow cytometry.

RESULTS

Compared to UT from control subjects (n = 15) and patients with CRS without NP (CRSsNP) (n = 16) and CRSwNP (n = 17), mRNAs for CD1a and CD1c were significantly elevated in NPs (n = 29). In contrast, CD207 mRNA was not elevated in NPs. Immunohistochemistry showed that CD1c(+) cells but not CD303(+) cells were significantly elevated in NPs compared to control subjects or patients with CRSsNP. Flow cytometric analysis showed that CD1a(+) cells in NPs might be a subset of mDC1s and that CD45(+) CD19(-) CD1c(+) CD11c(+) CD141(-) CD303(-) HLA-DR(+) mDC1s and CD45(+) CD19(-) CD11c(+) CD1c(-) CD141(high) HLA-DR(+) mDC2s were significantly elevated in NPs compared to UT from controls and CRSsNP, but CD45(+) CD11c(-) CD303(+) HLA-DR(+) pDCs were only elevated in NPs compared to control UT.

CONCLUSION AND CLINICAL RELEVANCE

Myeloid DCs are elevated in CRSwNP, especially in NPs. Myeloid DCs thus may indirectly contribute to the inflammation observed in CRSwNP.

Human mesothelioma induces defects in dendritic cell numbers and antigen-processing function which predict survival outcomes

Mesothelioma is an almost invariably fatal tumor with chemotherapy extending survival by a few months. One immunotherapeutic strategy is to target dendritic cells (DCs), key antigen-presenting cells involved in antigen presentation, to induce antigen-specific T cell responses. However, DC-targeting will only be effective if DCs are fit-for-purpose, and the functional status of DCs in mesothelioma patients was not clear. We found that mesothelioma patients have significantly decreased numbers of circulating myeloid (m)DC1 cells, mDC2 cells and plasmacytoid (p)DCs relative to healthy age and gender-matched controls. Blood monocytes from patients could not differentiate into immature monocyte-derived DCs (MoDCs), indicated by a significantly reduced ability to process antigen and reduced expression of costimulatory (CD40, CD80 and CD86) and MHC (HLA-DR) molecules, relative to controls. Activation of mesothelioma-derived MoDCs with LPS+/-IFNγ generated partially mature MoDCs, evident by limited upregulation of the maturation marker, CD83, and the costimulatory markers. Attempts to rescue mesothelioma-derived DC function using CD40Ligand(L) also failed, indicated by maintenance of antigen-processing capacity and limited upregulation of CD40, CD83, CD86 and HLA-DR. These data suggest that mesothelioma patients have significant numerical and functional DC defects and that their reduced capacity to process antigen and reduced expression of costimulatory molecules could induce anergized/tolerized T cells. Nonetheless, survival analyses revealed that individuals with mesothelioma and higher than median levels of mDC1s and/or whose MoDCs matured in response to LPS, IFNγ or CD40L lived longer, implying their selection for DC-targeting therapy could be promising especially if combined with another treatment modality.

SIV-induced Translocation of Bacterial Products in the Liver Mobilizes Myeloid Dendritic and Natural Killer Cells Associated With Liver Damage

Disruption of the mucosal epithelium during lentivirus infections permits translocation of microbial products into circulation, causing immune activation and driving disease. Although the liver directly filters blood from the intestine and is the first line of defense against gut-derived antigens, the effects of microbial products on the liver are unclear. In livers of normal macaques, minute levels of bacterial products were detectable, but increased 20-fold in simian immunodeficiency virus (SIV)-infected animals. Increased microbial products in the liver induced production of the chemoattractant CXCL16 by myeloid dendritic cells (mDCs), causing subsequent recruitment of hypercytotoxic natural killer (NK) cells expressing the CXCL16 receptor, CXCR6. Microbial accumulation, mDC activation, and cytotoxic NK cell frequencies were significantly correlated with markers of liver damage, and SIV-infected animals consistently had evidence of hepatitis and fibrosis. Collectively, these data indicate that SIV-associated accumulation of microbial products in the liver initiates a cascade of innate immune activation, resulting in liver damage.

Role of dendritic cell subsets in immunity and their contribution to noninfectious uveitis

Dendritic cells (DCs) are a heterogeneous population. Murine DCs consist of conventional DCs (cDCs) and plasmacytoid DCs (pDCs). In humans, the analogous populations are myeloid DCs (mDCs) and pDCs. Though distinct in phenotypes and functions, studies have shown that these DC subsets may interact or "crosstalk" during immune responses. For example, cDCs may facilitate pDC maturation, and pDCs may enhance antigen presentation of cDCs in certain pathogenic conditions or even take on a cDC phenotype themselves. The role of DCs in noninfectious uveitis has been studied primarily in the experimental autoimmune uveitis mouse model and to a more limited extent in patients. Recent evidence shows that the number, phenotype, and function of DC subsets are altered in this disease. We provide an overview of selected recent developments of pDCs and cDCs/mDCs, with special attention to their interaction and the dual roles of DC subsets in noninfectious uveitis.

Interleukin 23 produced by myeloid dendritic cells contributes to T-cell dysfunction in HIV type 1 infection by inducing SOCS1 expression

The mechanism of myeloid dendritic cell (mDC)-mediated impaired T-cell function was investigated during human immunodeficiency virus type 1 (HIV-1) infection. HIV or gp120 were found to inhibit lipopolysaccharide-induced mDC maturation and cause defects in allogeneic T-cell proliferation, interleukin 2 and interferon γ (IFN-γ) production, and phosphorylated STAT1 expression. gp120-treated mDCs downregulated autologous T-cell proliferation and IFN-γ production against a peptide pool consisting of cytomegalovirus, Epstein-Barr virus, and influenza virus (CEF). These T-cell defects were associated with a decrease in production of the T-helper type 1-polarizing cytokine interleukin 12p70 and an increase in interleukin 23 (IL-23) production by gp120-treated mDCs. gp120-induced IL-23 upregulated suppressor of cytokine signaling 1 (SOCS1) protein in T cells, which inhibited IFN-γ production and killing of CEF-pulsed monocytes. These effector functions were recovered by silencing SOCS1 in T cells. Furthermore, we observed IL-23-induced SOCS1 binding to the IFN-γ transcription complex. These results identify SOCS1 as a novel target to improve the immune function in HIV-infected persons.

The atopic skin-like microenvironment modulates the T-cell-polarising cytokine production of myeloid dendritic cells, as determined by laser scanning cytometry

Because it is not known exactly when or where myeloid dendritic cells (mDCs) acquire their atopic dermatitis (AD)-specific T-cell-polarising ability in patients with this condition, we used laser scanning cytometry (LSC) to determine whether isolated peripheral blood mDCs from AD patients differed from cells from controls in their cytokine expression profiles de novo and after stimulation with Staphylococcus enterotoxin B (SEB) and thymic stromal lymphopoietin (TSLP), which represents an AD-like microenvironment. Unstimulated mDCs from AD patients showed pluripotent T-cell-polarising capacity, and the surrounding skin microenvironment was essential for the distinctive, disease-specific activity of mDCs (Th2-Th22 bias). We also emphasise that LSC is an attractive technique to study the effect of new DC-targeted therapeutic modalities in AD.

Role of A20 in interferon-α-mediated functional restoration of myeloid dendritic cells in patients with chronic hepatitis C

Hepatitis C virus (HCV) infection is a global health problem characterized by a high rate of chronic infection, which may in part be due to a defect in myeloid dendritic cells (mDCs). This defect appears to be remedied by treatment with interferon-α (IFN-α) -based antiviral therapies; however, the molecular mechanisms underlying mDC dysfunction in HCV infection and restoration by IFN-α treatment are unclear. The ubiquitin-editing protein A20 plays a crucial role in controlling the maturation, cytokine production and immunostimulatory function of mDCs. We propose that the expression of A20 correlates with the function of mDCs during HCV infection and IFN-α therapy. In this study, we observed that A20 expression in mDCs isolated from chronically HCV-infected subjects was significantly higher than healthy subjects or subjects achieving sustained virological responses (SVR) following antiviral treatment. Notably, A20 expression in mDCs from HCV patients during IFN-α treatment was significantly lower than for untreated patients, SVR patients, or healthy subjects. Besides, A20 expression in mDCs stimulated by polyI:C differed between HCV patients and healthy subjects, and this difference could be abrogated by the treatment with IFN-α in vitro. Additionally, A20 expression by polyI:C-activated mDCs, with or without IFN-α treatment, negatively correlated with the expression of HLA-DR, CD86 and CCR7, and the secretion of interleukin-12 (IL-12), but positively associated with the production of IL-10. Importantly, silencing A20 expression using small interfering RNAs increased the production of IL-12 in mDCs of chronically HCV-infected individuals. These findings suggest that A20 plays a crucial role in negative regulation of innate immune responses during chronic viral infection.

Naturally circulating dendritic cells to vaccinate cancer patients

Dendritic cell-based immunotherapy is a promising strategy against cancer that appears to be feasible, safe and to induce potent tumor-specific immune responses. The use of naturally circulating dendritic cells (DCs), rather than cultured monocyte-derived DCs, might constitute the next logical step to translate anticancer immune responses into long-lasting clinical benefits.

Myeloid dendritic cells are primed in allergic asthma for thymic stromal lymphopoietin-mediated induction of Th2 and Th9 responses

BACKGROUND

Type 1 myeloid dendritic cells (mDCs) contribute to inception of allergic asthma (AA) and are regulated by epithelial-derived cytokines.

OBJECTIVES

To evaluate whether mDCs from AA patients are primed for thymic stromal lymphopoietin (TSLP)-driven responses.

METHODS

mDCs from 18 AA patients and 15 controls were purified using immunomagnetic sorting. Cells were pulsed with TSLP or Dermatophagoides pteronyssinus (Der p) allergen, before FACS phenotyping and co-culture with allogeneic CD4+ T cells. Bronchial biopsies from 15 AA patients and four controls were immunostained for CD1c and TSLP receptor (TSLPR).

RESULTS

Allergic asthma patients had a higher proportion of TSLPR+ mDCs, in blood and bronchial mucosa. When compared to mDCs from controls, both TSLP- and Der p-pulsed blood mDCs from AA patients induced increased polarization of CD4+ T cells into Th2 cells (IL-5, IL-13, and GATA3+), while only TSLP-mDCs promoted Th9 cells (IL-9 and PU.1+ /IRF4+). In addition, OX40L was induced upon TSLP stimulation and was required for the induction of Th2, but not Th9, cells. In contrast, development of Th9 cells in this model depended on TGF-β1.

CONCLUSIONS

Our data indicate overlapping but partially distinct effects of TSLP and Der p allergen pathways, showing that DCs are primed in human asthma for TSLP-driven induction of both Th2 and Th9 cells. This novel TSLP/mDC/Th9 axis operates through a distinct, OX40L-independent pathway. These data further highlight the TSLP pathway as a relevant target in human asthma.

Paradigm Shift in Dendritic Cell-Based Immunotherapy: From in vitro Generated Monocyte-Derived DCs to Naturally Circulating DC Subsets

Dendritic cell (DC)-based immunotherapy employs the patients’ immune system to fight neoplastic lesions spread over the entire body. This makes it an important therapy option for patients suffering from metastatic melanoma, which is often resistant to chemotherapy. However, conventional cellular vaccination approaches, based on monocyte-derived DCs (moDCs), only achieved modest response rates despite continued optimization of various vaccination parameters. In addition, the generation of moDCs requires extensive ex vivo culturing conceivably hampering the immunogenicity of the vaccine. Recent studies, thus, focused on vaccines that make use of primary DCs. Though rare in the blood, these naturally circulating DCs can be readily isolated and activated thereby circumventing lengthy ex vivo culture periods. The first clinical trials not only showed increased survival rates but also the induction of diversified anti-cancer immune responses. Upcoming treatment paradigms aim to include several primary DC subsets in a single vaccine as pre-clinical studies identified synergistic effects between various antigen-presenting cells.

CD141⁺ myeloid dendritic cells are enriched in healthy human liver

BACKGROUND & AIMS

Extensive populations of liver immune cells detect and respond to homeostatic perturbation caused by damage, infection or malignancy. Dendritic cells (DCs) are central to these activities, governing the balance between tolerance and immunity. Most of our knowledge about human liver DCs is derived from studies on peritumoral tissue. Little is known about the phenotype and function of DCs, in particular the recently described CD141(+) subset, in healthy human liver and how this profile is altered in liver disease.

METHODS

During liver transplantation, healthy donor and diseased explant livers were perfused and hepatic mononuclear cells isolated. Dendritic cell subset frequency and phenotype were characterised in liver perfusates by flow cytometry and the function of CD141(+) DCs was evaluated by mixed lymphocyte reactions (MLRs) and measuring cytokine secretion.

RESULTS

Almost one third of liver CD11c(+) myeloid DCs (mDCs) expressed CD141 compared to <5% of circulating mDCs. Hepatic CD141(+) DCs demonstrated pro-inflammatory function in allogeneic MLRs, inducing T cell production of interferon gamma (IFN-γ) and interleukin (IL)-17. While CD123(+) plasmacytoid DCs (pDCs) and CD1c(+) mDCs were expanded in diseased liver perfusates, CD141(+) DCs were significantly depleted. Despite their depletion, CD141(+) DCs from explant livers produced markedly increased poly(I:C)-induced IFN lambda (IFN-λ) compared with donor DCs.

CONCLUSIONS

Accumulation of CD141(+) DCs in healthy liver, which are significantly depleted in liver disease, suggests differential involvement of mDC subsets in liver immunity.

Tumoricidal activity of human dendritic cells

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Human DC subsets can exert tumoricidal activity.

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Killer DCs exploit several mechanisms for direct killing of target cells, including TRAIL and granzyme B.

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Antigen presentation and/or IFN production are important additional effector functions.

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Killer DCs are promising targets for immunotherapeutic strategies.

Dendritic cells (DCs) are a family of professional antigen-presenting cells (APCs) that are able to initiate innate and adaptive immune responses against pathogens and tumor cells. The DC family is heterogeneous and is classically divided into two main subsets, each with its unique phenotypic and functional characteristics: myeloid DCs (mDCs) and plasmacytoid DCs (pDCs). Recent results have provided intriguing evidence that both DC subsets can also function as direct cytotoxic effector cells; in particular, against cancer cells. In this review, we delve into this understudied function of human DCs and discuss why these so-called killer DCs might become important tools in future cancer immunotherapies.

Infliximab induces downregulation of the IL-12/IL-23 axis in 6-sulfo-LacNac (slan)+ dendritic cells and macrophages

BACKGROUND

The spectrum of TNF-α-producing cells in patients with psoriasis, as well as their fate during treatment with TNF-α antagonists, is not clearly defined.

OBJECTIVE

We sought to analyze the effects of anti-TNF-α treatment on TNF-α(+) cells in the skin and blood of patients with psoriasis.

METHODS

Lesional psoriatic skin was analyzed by means of immunohistologic staining and quantitative RT-PCR, and peripheral blood cells were phenotypically characterized by means of multicolor immunofluorescence labeling.

RESULTS

By using a tyramide-based signal amplification system, TNF-α was detected in dermal CD45(+)HLA-DR(+) leukocytes consisting of CD11c(+) dendritic cells and CD163(+) macrophages. In peripheral blood we observed an increase in the TNF-α-producing myeloid subsets of CD14(-) 6-sulfo-LacNac(+) dendritic cells and CD14(+)CD16(+) "intermediate" monocytes compared with healthy control subjects. Strikingly, we did not find detectable levels of TNF-α in other cells, including keratinocytes or T cells, making these cell types unlikely targets of TNF-α blockers. Up to 48 hours after the intravenous administration of the TNF-α antagonist infliximab, we encountered no overt changes in numbers of TNF-α(+) cells or signs of apoptosis in lesional psoriatic skin. Yet we observed a rapid decrease in IL-12p40, IL-1β, CCL20, and IL12RB1 mRNA levels. Consistently, TNF-α blockade during in vitro stimulation of 6-sulfo-LacNac DCs resulted in decreased production of IL-12 and IL-23 but not IL-6. In a mixed leukocyte reaction infliximab led to significantly decreased proliferation rates of T cells independent of the Fc antibody fragment.

CONCLUSION

The decrease in tissue inflammation during anti-TNF-α therapy is not due to immediate killing of TNF-α-producing cells but rather results from a rapid downregulation of the pathogenic IL-12/IL-23-driven immune response.

Characterization of clinical photosensitivity in cutaneous lupus erythematosus

BACKGROUND

Photosensitivity (PS) in lupus erythematosus (LE) is frequently determined by patient report.

OBJECTIVE

We sought to characterize self-reported PS in cutaneous LE (CLE).

METHODS

The PS survey was used to classify subject responses into 5 phenotypes: direct sun-induced CLE flare (directCLE); general exacerbation of CLE (genCLE); polymorphic light eruption-like reactions (genSkin); general pruritus/paresthesias (genRxn); and sun-induced systemic symptoms (genSys). In all, 91 subjects with CLE alone or with CLE and systemic LE were interviewed.

RESULTS

In all, 81% ascribed to 1 or more PS phenotypes. CLE-specific reactions (direct sun-induced CLE flare or general exacerbation of CLE) were reported by 86% of photosensitive subjects. Higher CLE disease activity (measured by CLE Disease Area and Severity Index activity scores) was suggestive of direct sun-induced CLE flare reactions (P = .09). In all, 60% of photosensitive subjects described CLE-nonspecific reactions: polymorphic light eruption-like rash and general pruritus/paresthesias. These phenotypes often co-occurred with CLE-specific reactions and were predicted by more systemic disease activity as measured by Physicians Global Assessment (PGA) scores in regression analyses (genSkin, P = .02) and (genRxn, P = .05). In all, 36% of subjects reported systemic reactions and higher PGA scores were predictive of the sun-induced systemic symptoms phenotype (P = .02); a diagnosis of systemic LE was not (P = .14).

LIMITATIONS

PS was inferred from patient report and not directly observed.

CONCLUSIONS

Characterization of self-reported PS in LE reveals that patients experience combinations of CLE-specific, CLE-nonspecific, and systemic reactions to sunlight. Sun-induced CLE flares are associated with more active CLE disease. Polymorphic light eruption-like, generalized pruritus/paresthesias, and systemic reactions are associated with more active systemic disease. Recognition of PS phenotypes will permit improved definitions of clinical PS and allow for more precise investigation into its pathophysiology.

Regulatory T cells, dendritic cells and neutrophils in patients with renal cell carcinoma

We evaluated dendritic cells (DC), regulatory T lymphocytes (Treg) and neutrophils in 37 patients with newly diagnosed renal cell carcinoma (RCC) in the tumor and peripheral blood (PB) and correlated these parameters with tumor staging (early-T1, 2, late-T3, 4 and metastatic disease). The number of myeloid and plasmacytoid DC in blood of RCC patients was higher than in healthy controls. The percentage of myeloid dendritic cells (mDC) from CD45+ cells in tumors was higher in comparison with peripheral blood irrespective of disease stage. Higher percentage of these cells expressed a maturation marker in the periphery in the early stage (CD83 expressing cells). The number of plasmacytoid dendritic cells (pDC) in PB was similar in both early and late stage groups, but the early group displayed a significantly higher percentage of pDC in tumor cell suspension. Neutrophil counts in the peripheral blood of RCC patients were higher than in healthy controls, but the counts in both tumor stage groups were similar. The proportion of neutrophils from CD45+ cells was higher in late stage tumors. Higher percentage of Treg from CD4+ cells was detected in renal carcinoma tissue in comparison to PB with no difference between stages of the disease. Our results reflect the complex interplay between various cells of the immune system and the tumor microenvironment. Activation of dendritic cell subpopulations at early stages of the disease course is counterbalanced by the early appearance of T regulatory cells both in the periphery and tumor tissue. Later stages are characterized by the accumulation of neutrophils in the tumor. Appropriate timing of anticancer strategies, especially immunotherapy, should take these dynamics of the immune response in RCC patients into account.

Comparative analysis of dendritic cell numbers and subsets between smoking and control subjects in the peripheral blood

It has been well known that smoking alters the property and functionality of a wide range of immune cells including dendritic cells (DCs). However, a great deal of effort in the past has been mainly devoted to dissect the effect of smoking on pulmonary DCs, while its exact impact on circulating DCs remains to be fully addressed. Therefore, in the present report we particularly examined the impact of smoking on the number and subset of DCs in the peripheral blood by multi-parametric flow cytometry analysis. A significant increase for peripheral blood mononuclear cells (PBMCs) was noted in the smoking subjects. Subsequent studies revealed that the percentage for plasmacytoid DCs (pDCs) and total DCs in PBMCs was significantly higher in the smoking subjects as compared with that of control subjects, while the percentage for myeloid DCs (mDCs) did not differ between two groups. It was also found that the absolute number for total DCs, mDCs and pDCs were significantly higher in the smoking subjects than that of control subject. However, the mDC/pDC ratio was significantly reduced, suggesting that smoking impairs the balance of DC subsets. Given that pDCs are in favor of tolerogenic function, our data support that smoking could induce the production of pDCs to manifest immunosuppressive properties in the chronic smokers.

In situ analysis of FOXP3+ regulatory T cells and myeloid dendritic cells in human colorectal cancer tissue and tumor-draining lymph node

Forkhead box protein 3 (FOXP3) regulatory T cells (Tregs) are important in the maintenance of tumor immunity tolerance. Myeloid dendritic cells (mDCs) are antigen-presenting cells (APCs) specialized to initiate and regulate immunity. Tregs and mDCs are suspected of influencing the interaction between the tumor and immune system, and thus the course of tumors. However, the implication and interaction of their concurrent infitration in colorectal cancer (CRC) remain unknown. The aim of this study was to determine FOXP3⁺ Tregs and CD11c⁺ mDCs infiltration in CRC and tumor-draining lymph node (TDLN) and to explore the clinical and pathological implication of suppressor and effector immune cell subsets. Immunohistochemical assay was conducted to assess FOXP3⁺ Tregs and CD11c⁺ mDCs infiltration in tumor tissue and in metastasis-free TDLN (mfTDLN) and metastatic TDLN (mTDLN). The results showed that FOXP3⁺ Tregs and CD11c⁺ mDCs infiltration was higher in tumor tissue compared to adjacent normal mucosa (P<0.001). FOXP3⁺ Tregs infiltration was associated with advanced tumor-node-metastasis (TNM) stage and lymph node metastasis (P<0.001 and P<0.001, for TNM stage and lymph node metastasis, respectively), whereas less CD11c⁺ mDCs infiltration of tumor in situ was associated with deeper tumor invasion, advanced TNM stages and lymph node metastasis (P<0.05, P<0.001 and P<0.001, for tumor invasion depth, TNM stages and lymph node metastasis, respectively). Compared to mfTDLN, mTDLN was significantly enriched in FOXP3⁺ Tregs (P<0.001) and reduced in CD11c⁺ mDCs (P<0.001). The statistical analysis demonstrated no significant correlations in Tregs and mDCs infiltration. These results suggest that more FOXP3⁺ Tregs and less CD11c⁺ mDCs infiltration have stronger prognostic significance in CRC. The presence of tumor cells in mTDLN may contribute to a tolerogenic milieu and facilitate the survival of metastatic tumor cells.

Toll-like receptor expression and function in human dendritic cell subsets: implications for dendritic cell-based anti-cancer immunotherapy

Dendritic cells (DCs) are central players of the immune response. To date, DC-based immunotherapy is explored worldwide in clinical vaccination trials with cancer patients, predominantly with ex vivo-cultured monocyte-derived DCs (moDCs). However, the extensive culture period and compounds required to differentiate them into DCs may negatively affect their immunological potential. Therefore, it is attractive to consider alternative DC sources, such as blood DCs. Two major types of naturally occurring DCs circulate in peripheral blood, myeloid DCs (mDCs) and plasmacytoid (pDCs). These DC subsets express different surface molecules and are suggested to have distinct functions. Besides scavenging pathogens and presenting antigens, DCs secrete cytokines, all of which is vital for both the acquired and the innate immune system. These immunological functions relate to Toll-like receptors (TLRs) expressed by DCs. TLRs recognize pathogen-derived products and subsequently provoke DC maturation, antigen presentation and cytokine secretion. However, not every TLR is expressed on each DC subset nor causes the same effects when activated. Considering the large amount of clinical trials using DC-based immunotherapy for cancer patients and the decisive role of TLRs in DC maturation, this review summarizes TLR expression in different DC subsets in relation to their function. Emphasis will be given to the therapeutic potential of TLR-matured DC subsets for DC-based immunotherapy.

Impaired functionality and phenotypic profile of dendritic cells from patients with multiple myeloma

Multiple myeloma (MM) is a B cell cancer characterized by clonal proliferation in the bone marrow and impaired immunity. Because MM is an incurable malignancy, efficient consolidation is needed urgently. Targeting clonotypic B cells by idiotype vaccination has proved the principle to be effective and indicated that future strategies, including dendritic cell-based vaccination, could be a suitable approach. However, as MM patients suffer from a general impaired immunity, which may include dendritic cells (DCs), a careful evaluation of phenotypic traits and functionality of DCs from MM patients is necessary before an efficient vaccine can be developed. This study determined the number, phenotypic profile and functionality of myeloid and plasmacytoid DCs purified directly from blood from MM patients at diagnosis. A reduced number and lower expression of human leucocyte antigen (HLA) molecules was observed on both myeloid and plasmacytoid DCs in MM patients compared to healthy controls. Also, the expression of CCR5, CCR7 and DEC205 was lower in MM patients compared to normal donors. In addition, the capacity to stimulate allogeneic T cell proliferation and to stimulate cytokine production was decreased, suggesting that DCs from these patients are functionally impaired. Finally, the analysis of samples following chemotherapy and transplantation demonstrated an increased expression of HLA molecules, suggesting that this time-point is optimal for harvest and use in vaccination.