Carcinogen-modified dendritic cells induce immunosuppression by incomplete T-cell activation resulting from impaired antigen uptake and reduced CD86 expression

Expression and distribution of S-100, CD83, and costimulatory molecules (CD80 and CD86) in tissues of thyroid papillary carcinoma

A higher expression of S-100 in tissue of thyroid papillary carcinoma (TPC) vs. thyroid follicular adenoma (TFA) (p < .001) was observed as well as a higher expression of CD83 in the peri-cancerous tissues vs. TFA (p < .001), oppositely, CD83 was negative in the cancerous net. TPC showed greater decreases in levels of CD80 and CD86 than did the TFA. These findings suggest that impaired immune function, absence of CD83-positive mature and activated dendritic cells in cancer nodules may have a role in the pathogenesis of TPC. The low expression of CD80 and CD86 in TPC may help them evade the immune system.

The low expression of CD80 correlated with the vascular endothelial growth factor in esophageal cancer tissue

AIMS

To analyze the mRNA and protein expression of CD80 and vascular endothelial growth factor (VEGF) in esophageal cancer (EC) tissue, investigate the causes of esophageal cancer cell escape from immune surveillance.

METHODS

We detected the CD80 and VEGF mRNA with reverse transcription polymerase chain reaction (RT-PCR), CD80 protein with flow cytometry, VEGF protein with immunohistochemistry in the cancer tissues in 118 EC patients, and the normal esophageal tissue as controls.

RESULTS

The expression of CD80 mRNA and protein in cancer tissues were lower than that in the controls (p<0.01, respectively), The CD80 protein expression in poor differentiation was lower than that in the well and moderate (P<0.01), in the patients with lymph node metastasis lower than that with no metastasis (P=0.01), in stage IIIA patients lower than that in stages I and II patients (P=0.04); the VEGF mRNA and protein expression were just right opposite. The mean survival time in the CD80 positive group was significantly longer than that in the negative (p=0.041); while in VEGF positive group was lower than that in the negative (p=0.046). The CD80 expression of mRNA and protein were correlated negatively with VEGF in the cancer tissues (r=-0.82, -0.87, respectively).

CONCLUSION

It is suggested that CD80 was impaired in the EC tissues and correlated with the clinicopathological characteristics and prognosis, which indicated the dysfunction of immune system and enhancing the progression of EC. The low expression of CD80 correlated with the overexpression of VEGF.

The humoral immune response of mice exposed to simulated road paving-like asphalt fumes

Asphalt is a complex mixture of organic molecules, including polycyclic aromatic hydrocarbons (PAH), which have been reported to cause serious adverse health effects in humans. Workers in manufacturing and construction trades exposed to asphalt are potentially at risk for being exposed to asphalt fumes and PAHs. Epidemiological investigations have collected mounting evidence that chemicals found in asphalt fumes present carcinogenic and possibly immunotoxic hazards. Studies evaluating the immunotoxic effects of asphalt fume are limited due to the large number of variables associated with asphalt fume exposures. This work investigates the immuno-toxic effects of road paving-like asphalt fume by analyzing the in vivo IgM response to a T-dependent antigen after exposure to whole, vapor, and particulate phase road paving-like asphalt fumes and asphalt fume condensate. Systemic exposures via intraperitoneal injection of asphalt fume condensate (at 0.625 mg/kg) and the particulate phase (at 5 mg/kg) resulted in significant reductions in the specific spleen IgM response to SRBC. Pharyngeal aspiration of the asphalt fume condensate (at 5 mg/kg) also resulted in significant suppression of the IgM response to SRBC. A significant reduction in the specific spleen IgM activity was observed after inhalation exposure to whole asphalt fumes (35 mg/m(3)) and the vapor components (11 mg/m(3)). Dermal exposures to the asphalt fume condensate resulted in significant reductions in the total (at 50 mg/kg) and specific (at 250 mg/kg) spleen IgM response to SRBC. These results demonstrate that exposure to road paving-like asphalt fumes is immunosuppressive through systemic, respiratory, and dermal routes of exposure in a murine model and raise concerns regarding the potential for adverse immunological effects.

Primary Defect in UVB-Induced Systemic Immunomodulation Does Not Relate to Immature or Functionally Impaired APCs in Regional Lymph Nodes

UVB irradiation of the shaved dorsal skin of mice can cause both local and systemic suppression of contact hypersensitivity responses; the former demonstrated by administration of the sensitizing Ag/hapten to the irradiated site and the latter by its administration at least 72 h later to distal unirradiated sites. The immunological basis of systemic immunomodulation is not clear. When haptens (trinitrochlorobenzene, FITC) were administered to the shaved ventral skin 4 days after irradiation (8 kJ/m(2)) to the shaved dorsum of BALB/c mice, CD11c(+)/FITC(+) cells in the skin-draining lymph nodes from control and irradiated mice produced on a per cell basis similar levels of IL-12 and PGE(2) were phenotypically mature and efficient at presenting FITC to lymphocytes from FITC-sensitized mice. Ag presentation by FACS-sorted CD11c(+) lymph node cells isolated 4 days after UVB irradiation was as efficient as were cells from unirradiated mice at presentation in vitro of an OVA peptide (OVA(323-339)) to CD4(+) cells from OVA-TCR-transgenic DO11.10 mice. Further, IFN-gamma levels were increased in the cultures containing CD11c(+) cells from UVB-irradiated mice, suggesting that inflammation may precede downstream immunosuppression. These results suggest that the primary cause of reduced contact hypersensitivity responses in mice in which UV irradiation and the sensitizing Ag are applied to different sites several days apart must originate from cells other than CD11c(+) APCs that directly or by production of soluble mediators (IL-12, PGE(2)) affect cellular responses in the nodes of UVB-irradiated mice.

Study on immune function of dendritic cells in patients with esophageal carcinoma

AIM: To investigate the immune function of dendritic cells from both peripheral blood and operated tissues of esophageal carcinoma patients in order to find the relationship between the immune function of dendritic cells and the pathogenesis of esophageal carcinoma.

METHODS: The expression of CD83, CD80, and CD86 on the surface of dendritic cells cultured from the peripheral blood of patients was detected compared with that from health donors using flow cytometry. The ability of dendritic cells to induce T lymphocyte proliferation was evaluated by a liquid scintillation counter. The expression of CD80, CD86, CD83, and S-100 proteins was assessed in esophageal carcinoma tissues using immunohistochemical method.

RESULTS: Compared with those from healthy donors, dendirtic cells cultured from the peripheral blood of patients expressed lower CD80 and CD86. Furthermore, the ability of dendritic cells in patients to induce T lymphocyte proliferation was significantly lower than that of the control group. Compared with the control group, the positive expression ratio and frequencies of CD80, CD86, and S-100 in esophageal carcinoma tissues were significantly down regulated. The expression of CD83 was up-regulated in the pericancerous tissues, but no expression was found in the cancerous nodules.

CONCLUSION: The impaired immune function and the decreased number of dendritic cells cause pathogenesis and progression of esophageal carcinoma.

Identification of Na+/H+exchange as a new target for toxic polycyclic aromatic hydrocarbons in liver cells

The ubiquitous environmental pollutants polycyclic aromatic hydrocarbons are responsible for important carcinogenic and apoptotic effects, whose mechanisms are still poorly understood, owing to the multiplicity of possible cellular targets. Among these mechanisms, alterations of ionic homeostasis have been suggested. In this work, the effects of benzo(a)pyrene [B(a)P] on pHi were tested in the rat liver F258 epithelial cell line, using the fluoroprobe carboxy-SNARF-1. After a 48-h treatment, B(a)P (50 nM) induced an alkalinization, followed by an acidification after 72 h and the development of apoptosis. Determinations of pH(i) recovery following an acid load showed an increased acid efflux at 48 h. Cariporide inhibited both the early alkalinization and the increased acid efflux, thus suggesting the involvement of Na+/H+ exchanger 1 (NHE1). Besides, alpha-naphtoflavone (alpha-NF), an inhibitor of CYP1A1-mediated B(a)P metabolism, prevented all pH(i) changes, and NHE1 activation was blocked by the antioxidant thiourea, which inhibited CYP1A1 metabolism-dependent H2O2 production. Regarding B(a)P-induced apoptosis, this was prevented by alpha-NF and bongkrekic acid, an inhibitor of mitochondria-dependent apoptosis. Interestingly, apoptosis was significantly reduced by cariporide. Taken together, our results indicate that B(a)P, via H2O2 produced by CYP1A1-dependent metabolism, induces an early activation of NHE1, resulting in alkalinization; this appears to play a significant role in mitochondria-dependent B(a)P-induced apoptosis.

Impaired CD40-signalling in Langerhans' cells from murine neonatal draining lymph nodes: implications for neonatally induced cutaneous tolerance

Cutaneous tolerance to antigens may be induced in mice through application of antigen during the first few days following birth. The mechanism governing this neonatally induced tolerance remains uncertain. We employed a contact hypersensitivity model to analyse dendritic cell (DC) function and the expression of classical and non-classical lymphocyte populations within the neonate. Examination of draining lymph node DC after antigenic challenge of the skin revealed these DC to be significantly deficient in their ability to stimulate antigen-specific T cell proliferation. Co-stimulatory molecule (CD40, CD80 and CD86) expression of these cells was deficient in comparison to adult DC, and functional tests revealed these cells to possess a critical absence of CD40 signalling. A numerical analysis of classical and non-classical lymphocyte expression demonstrated that while the neonatal spleen is devoid of T cells, the lymph nodes have a normal repertoire of T, B, gammadelta and CD4+CD25+ lymphocytes but an increased expression of natural killer (NK) cells. This study indicates that functionally deficient DC are likely contributors to neonatally induced cutaneous tolerance.

Gene-modified dendritic cells for immunotherapy against cancer

Dendritic cells (DCs) are described as professional antigen-presenting cells because of their superior T-cell stimulatory capacity. For this reason, attention is being focused on using DCs for clinical applications to treat cancer patients. Although preclinical studies are promising, the majority of clinical studies with DCs have not fulfilled the expectations, yet. The field of DC biology has progressed rapidly over the past years, leading to several options for the improvement of vaccination. Among the different parameters to investigate, this review focuses on the efficiency and biological and functional consequences of different gene transfer methods into different subsets of human DCs. Another important consideration for DC-based vaccination is the elucidation of the role of maturation and apoptosis during DC differentiation.

Resistance to alopecia areata in C3H/HeJ mice is associated with increased expression of regulatory cytokines and a failure to recruit CD4+ and CD8+ cells

Grafting alopecia areata affected C3H/HeJ mouse skin to littermates induces alopecia areata, but high dietary soy oil reduces alopecia areata susceptibility. Alopecia areata affected and resistant mice were characterized to evaluate possible mechanisms involved in alopecia areata resistance. Of 44 mice that received alopecia areata affected skin grafts but failed to develop alopecia areata, only two of 22 receiving further alopecia areata affected skin grafts developed alopecia areata, whereas 39 of 44 controls developed alopecia areata. Alopecia areata affected skin contained increased numbers of CD4+ and CD8+ cells, increases in pro inflammatory T helper 1 and T helper 2 type cytokines, and upregulation of CD28, CD40L, and their ligands. In draining lymph nodes, a relatively high number of antigen-presenting cells was recovered, whereas several CD44v variants were downregulated. In contrast, alopecia areata resistant mouse skin did not display increased numbers of CD4+ and CD8+ cells, whereas counter-regulatory cytokines interleukins 4 and 10 were upregulated. High expression of CD28, CD80, CD86, CD40, CTLA4, CD44v variants, and FasL occurred in alopecia areata resistant mouse spleens. In vitro, lymph node cells of susceptible and resistant mice responded equally to a mitogenic stimulus, but only lymph node cells from alopecia areata affected mice displayed an increased response with T cell receptor stimulation via anti-CD3 cross-linking. These results suggest alopecia areata is a cell-mediated autoimmune disease, but alopecia areata affected skin graft hosts may resist alopecia areata onset through active counter-regulatory mechanisms. Because alopecia areata resistant mice showed unimpaired responsiveness and a transient inflammatory response towards the graft, it is suggested that alopecia areata develops as a consequence of an inappropriate immune response regulation.

2,3,7,8-Tetrachlorodibenzo-p-dioxin suppresses tumor necrosis factor-alpha and anti-CD40-induced activation of NF-kappaB/Rel in dendritic cells: p50 homodimer activation is not affected

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) suppresses many immune responses, both innate and adaptive. Suppression is mediated by the aryl hydrocarbon receptor (AhR), a ligand-activated transcription factor. The AhR mediates TCDD toxicity presumably through the alteration of transcriptional events, either by promoting gene expression or potentially by physically interacting with other transcription factors. Another transcription factor, NF-kappaB/Rel, is involved in several signaling pathways in immune cells and is crucial for generating effective immune responses. Dendritic cells (DCs), considered to be the "pacemakers" of the immune system, were recently recognized as targets of TCDD and are also dependent on NF-kappaB/Rel for activation and survival. In these studies, we investigated whether TCDD would alter the activation of NF-kappaB/Rel in DCs. The dendritic cell line DC2.4 was exposed to TCDD before treatment with tumor necrosis factor alpha (TNF-alpha) or anti-CD40, and NF-kappaB/Rel activation was measured by electrophoretic mobility shift assay and immunoblotting. TCDD suppressed the binding of NF-kappaB/Rel to its cognate response element in TNF-alpha- and anti-CD40-treated cells and blocked translocation to the nucleus. The AhR was shown to associate with RelA, after coimmunoprecipitation, and seemed to block its binding to DNA. It is noteworthy that p50 homodimers freely bound to DNA. These results suggest that TCDD may alter the balance between NF-kappaB/Rel heterodimers and transcriptional inhibitory p50 homodimers in DCs, leading to defects in the DCs and suppression of the immune response.

Hazardous air pollutants and asthma

Asthma has a high prevalence in the United States, and persons with asthma may be at added risk from the adverse effects of hazardous air pollutants (HAPs). Complex mixtures (fine particulate matter and tobacco smoke) have been associated with respiratory symptoms and hospital admissions for asthma. The toxic ingredients of these mixtures are HAPs, but whether ambient HAP exposures can induce asthma remains unclear. Certain HAPs are occupational asthmagens, whereas others may act as adjuncts during sensitization. HAPs may exacerbate asthma because, once sensitized, individuals can respond to remarkably low concentrations, and irritants lower the bronchoconstrictive threshold to respiratory antigens. Adverse responses after ambient exposures to complex mixtures often occur at concentrations below those producing effects in controlled human exposures to a single compound. In addition, certain HAPs that have been associated with asthma in occupational settings may interact with criteria pollutants in ambient air to exacerbate asthma. Based on these observations and past experience with 188 HAPs, a list of 19 compounds that could have the highest impact on the induction or exacerbation of asthma was developed. Nine additional compounds were identified that might exacerbate asthma based on their irritancy, respirability, or ability to react with biological macromolecules. Although the ambient levels of these 28 compounds are largely unknown, estimated exposures from emissions inventories and limited air monitoring suggest that aldehydes (especially acrolein and formaldehyde) and metals (especially nickel and chromium compounds) may have possible health risk indices sufficient for additional attention. Recommendations for research are presented regarding exposure monitoring and evaluation of biologic mechanisms controlling how these substances induce and exacerbate asthma.

Acquisition of immune function during the development of the Langerhans cell network in neonatal mice

The immunological function of the Langerhans cell (LC) network in neonatal skin was examined by defining the development of cutaneous immunity relative to the structure, phenotype and function of the epidermal LC network in neonatal, juvenile and adult mice. Analysis of epidermal sheets showed the presence of major histocompatibility complex (MHC) II+, multilectin receptor DEC-205- cells within the epidermis of 3-day-old mice; both cell density and DEC-205 expression increased until day 14. When visualized with antibodies directed at MHC II, the network was poorly formed in 3- and 7-day-old mice, as there was a lower cell density and poor MHC II expression on dendritic processes, compared to mice at day14. Application of a fluorescent antigen to 3-day-old mice revealed that the LC were inefficient in transporting antigen to the draining lymph node. There was an improvement at day 7 and by day 14 comparable numbers of antigen carrying cells were detected in the lymph nodes of 6-week-old mice. The reduced antigen carriage in 3- and 7-day-old mice correlated with a poor contact sensitivity response. This was not simply due to failure to present antigen, but development of immunosuppression, as transfer of T cells from adult mice that were previously treated with antigen when they were 3 days old, to adult recipients resulted in antigen specific immunosuppression. Analysis of CD80 and CD86 expression showed that LC from day 3 skin expressed CD80, but not CD86 and application of antigen through this skin was inefficient in upregulating CD86. These findings indicate that when the neonatal LC network is poorly developed it is functionally immature and antigen applied through this 'functionally immature network' results in antigen specific immunosuppression.

Prevention of autoimmunity by induction of cutaneous tolerance

Autoimmune gastritis develops in 20-60% of BALB/c mice following thymectomy at 3 days after birth (3dnTx). Previously we identified the gastric H+/K+ ATPase as the causative autoantigen and mapped the immunoreactive T cell epitope to a carboxyl-terminal peptide on the gastric H+/K+ ATPase beta subunit. Here we show that autoimmune gastritis can be suppressed by immunizing 3dnTx mice through neonatal skin with the beta subunit peptide, in combination with the contact sensitizer TNCB. When spleen cells were transferred from suppressed mice to nude mice a proportion of recipient mice developed gastritis. These results indicate that pathogenic T cells were still present in the 3dnTx mice but the absence of gastritis indicates that their activity can be regulated following induction of cutaneous tolerance by immunizing through neonatal skin. We propose that cutaneous tolerance is induced through mediation of immature Langerhans cells in neonatal skin and that this tolerance prevented the autoreactivity of pathogenic T cells. This procedure will have implications for strategies to suppress autoimmunity.