Comparing the effects of an exposure to a polycyclic aromatic hydrocarbon mixture versus individual polycyclic aromatic hydrocarbons during monocyte to macrophage differentiation: Mixture exposure results in altered immune metrics

Polycyclic aromatic hydrocarbons (PAHs) are generated by the incomplete combustion of carbon. Exposures correlate with systemic immune dysfunction and overall immune suppression. Real-world exposures to PAHs are almost always encountered as mixtures; however, research overwhelmingly centers on isolated exposures to a single PAH, benzo[a]pyrene (B[a]P). Here, a human monocyte line (U937) was exposed to B[a]P, benz[a]anthracene (B[a]A), or a mixture of six PAHs (6-MIX) to assess the differential toxicity on monocytes. Further, monocytes were exposed to PAHs with and without CYP1A1 inhibitors during macrophage differentiation to delineate PAH exposure and PAH metabolism-driven alterations to the immune response. U937 monocytes exposed to B[a]P, B[a]A, or 6-MIX had higher levels of cellular health and growth not observed following equimolar exposures to other individual PAHs. PAH exposures during differentiation did not alter monocyte-derived macrophage (MDM) numbers; however, B[a]A and 6-MIX exposures significantly altered M1/M2 polarization in a CYP1A1-dependent manner. U937-MDM adherence was differentially suppressed by all three PAH treatments with 6-MIX exposed U937-MDM having significantly more adhesion than U937-MDM exposed to either individual PAH. Finally, 6-MIX exposures during differentiation reduced U937-MDM endocytic function significantly less than B[a]A exposed cells. Exposure to a unique PAH mixture during U937-MDM differentiation resulted in mixture-specific alterations of pro-inflammatory markers compared to individual PAH exposures. While subtle, these differences highlight the probability that using a model PAH, B[a]P, may not accurately reflect the effects of PAH mixture exposures. Therefore, future studies should include various PAH mixtures that encompass probable real-world PAH exposures for the endpoints under investigation.

"Structural imprinting" of the cutaneous immune effector function

Keratinization provides tolerance to desiccation and mechanical durability. Loricrin, which is an epidermal thiol-rich protein, efficiently stabilizes terminally differentiated keratinocytes and maintains redox homeostasis. The discovery of the largely asymptomatic loricrin knockout (LKO) phenotype decades ago was rather unpredicted. Nevertheless, when including redox-driven, NF-E2-related factor 2-mediated backup responses, LKO mice provide opportunities for the observation of altered or "quasi-normal" homeostasis. Specifically, given that the tissue structure, as well as the local metabolism, transmits immunological signals, we sought to dissect the consequence of truncated epidermal differentiation program from immunological perspectives. Through a review of the aggregated evidence, we have attempted to generate an integrated view of the regulation of the peripheral immune system, which possibly occurs within the squamous epithelial tissue with truncated differentiation. This synthesis might not only provide insights into keratinization but also lead to the identification of factors intrinsic to the epidermis that imprint the immune effector function.

Cigarette smoke exposure reduces leukemia inhibitory factor levels during respiratory syncytial viral infection

Background: Viral infections are considered a major driving factor of chronic obstructive pulmonary disease (COPD) exacerbations and thus contribute to disease morbidity and mortality. Respiratory syncytial virus (RSV) is a frequently detected pathogen in the respiratory tract of COPD patients during an exacerbation. We previously demonstrated in a murine model that leukemia inhibitory factor (LIF) expression was increased in the lungs during RSV infection. Subduing LIF signaling in this model enhanced lung injury and airway hypersensitivity. In this study, we investigated lung LIF levels in COPD patient samples to determine the impact of disease status and cigarette smoke exposure on LIF expression. Materials and methods: Bronchoalveolar lavage fluid (BALF) was obtained from healthy never smokers, smokers, and COPD patients, by written informed consent. Human bronchial epithelial (HBE) cells were isolated from healthy never smokers and COPD patients, grown at the air-liquid interface and infected with RSV or stimulated with polyinosinic:polycytidylic acid (poly (i:c)). Mice were exposed to cigarette smoke daily for 6 months and were subsequently infected with RSV. LIF expression was profiled in all samples. Results: In human BALF, LIF protein was significantly reduced in both smokers and COPD patients compared to healthy never smokers. HBE cells isolated from COPD patients produced less LIF compared to never smokers during RSV infection or poly (i:c) stimulation. Animals exposed to cigarette smoke had reduced lung levels of LIF and its corresponding receptor, LIFR. Smoke-exposed animals had reduced LIF expression during RSV infection. Two possible factors for reduced LIF levels were increased LIF mRNA instability in COPD epithelia and proteolytic degradation of LIF protein by serine proteases. Conclusions: Cigarette smoke is an important modulator for LIF expression in the lungs. Loss of LIF expression in COPD could contribute to a higher degree of lung injury during virus-associated exacerbations.

[Experience of culturing anterior epithelial corneal cells from human eye ball]

Adult corneal epithelium is often exposed to environmental stress, injured and repaired by limbal stem cells. Injury of corneal epithelial layer leads to reduction of visual clarity and loss of vision. Recently it was shown that epithelial layer also contains stem cells. Obtaining cell culture of corneal epithelium will allow understanding mechanisms of cell behavior and differentiation, their metabolism and reaction on environmental stress in health and disease. Moreover, cultured corneal epithelial cells can be considered as a promising material for constructing bioartificial cornea. The aim of this study was to isolate cells of anterior corneal epithelium from human donor cornea and to study their morphological and functional characteristics in vitro. The results of our study showed the possibility of culturing epithelial cells in vitro. The observed changes in cell morphology, their flow growth character as well as active proliferation and up-regulation of mesenchymal markers expression, indicate, in our opinion, epithelial-mesenchymal transition taking place in long-lasting culture of human anterior corneal epithelial cells. The obtained cultures can be used for further studies of pathological processes taking place in cells during drugs testing or controlling the phototoxic effect of different types of emission.

Effects of sex hormones on inflammatory response in male and female vascular endothelial cells

PURPOSE

Gender-related differences in sex hormones might have a key role in the development of atherosclerosis though direct vascular effects of sex hormones are not yet well understood. Thus, the main purpose of this study was to compare the effects of sex hormones on inflammatory response in Human Umbilical Vein Endothelial Cells (HUVECs) obtained from both male and female donors.

METHODS

We analyzed the expression of receptors and enzymes relevant to the action of androgens (AR, 5α-reductase 1 and 5α-reductase 2) and estrogens (ERα, ERβ, and aromatase) in male and female HUVECs. Furthermore, we analyzed the effect of testosterone (T), 17β-estradiol (E2), dihydrotestosterone (DHT), and several androgenic-anabolic steroids (AAS) on VCAM-1, ICAM-1, and E-selectin gene expression and on adhesion of U937 cells to TNF-α-stimulated male and female HUVECs.

RESULTS

Our results reveal that in HUVECs, regardless of gender, the components involved in the androgen action pathway are predominant as compared to those of estrogen action pathway. In both HUVEC genders, the inflammatory effect of TNF-α was amplified by co-administration of T or DHT and several AAS frequently used in doping, while E2 had no effect.

CONCLUSIONS

This is the first study analyzing, under identical culture conditions, the key components of sex hormone response in male and female HUVECs and the possible role of sex hormones in regulating the endothelial inflammatory response. The data obtained in our experimental system showed a pro-inflammatory effect of androgens, while conclusively excluding any protective effect for all the tested hormones.

Dendritic cell vaccines for leukemia patients

Dendritic cells are the most professional antigen-presenting cells to elicit T-cellular responses toward microbial agents and cancer cells. The graft-versus-leukemia effect observed after allogeneic stem cell transplantation strongly suggests that T lymphocytes play a major role in the rejection of leukemic cells. This graft-versus-leukemia effect might be enhanced through dendritic cell vaccination. The characterization of leukemia-specific antigens eliciting immune responses in the autologous host has prompted researchers and clinicians to broaden the spectrum of dendritic cell vaccines to hematological malignancies. Recently, the focus is on acute myeloid leukemia and chronic lymphocytic leukemia. This review summarizes data on the administration of autologous and allogeneic dendritic cells to leukemia patients as an interesting approach in cellular therapy of leukemias.

Innate signaling promotes formation of regulatory nitric oxide-producing dendritic cells limiting T-cell expansion in experimental autoimmune myocarditis

BACKGROUND

Activation of innate pattern-recognition receptors promotes CD4+ T-cell-mediated autoimmune myocarditis and subsequent inflammatory cardiomyopathy. Mechanisms that counterregulate exaggerated heart-specific autoimmunity are poorly understood.

METHODS AND RESULTS

Experimental autoimmune myocarditis was induced in BALB/c mice by immunization with α-myosin heavy chain peptide and complete Freund's adjuvant. Together with interferon-γ, heat-killed Mycobacterium tuberculosis, an essential component of complete Freund's adjuvant, converted CD11b(hi)CD11c(-) monocytes into tumor necrosis factor-α- and nitric oxide synthase 2-producing dendritic cells (TipDCs). Heat-killed M. tuberculosis stimulated production of nitric oxide synthase 2 via Toll-like receptor 2-mediated nuclear factor-κB activation. TipDCs limited antigen-specific T-cell expansion through nitric oxide synthase 2-dependent nitric oxide production. Moreover, they promoted nitric oxide synthase 2 production in hematopoietic and stromal cells in a paracrine manner. Consequently, nitric oxide synthase 2 production by both radiosensitive hematopoietic and radioresistant stromal cells prevented exacerbation of autoimmune myocarditis in vivo.

CONCLUSIONS

Innate Toll-like receptor 2 stimulation promotes formation of regulatory TipDCs, which confine autoreactive T-cell responses in experimental autoimmune myocarditis via nitric oxide. Therefore, activation of innate pattern-recognition receptors is critical not only for disease induction but also for counterregulatory mechanisms, protecting the heart from exaggerated autoimmunity.

Enhancing cytokine-induced killer cell therapy of multiple myeloma

Cytokine-induced killer (CIK) cells are in clinical testing against various tumor types, including multiple myeloma. In this study, we show that CIK cells have activity against subcutaneous and disseminated models of human myeloma (KAS-6/1), which can be enhanced by infecting the CIK cells with an oncolytic measles virus (MV) or by pretreating the myeloma cells with ionizing radiation (XRT). KAS-6/1 cells were killed by coculture with CIK or MV-infected CIK (CIK/MV) cells, and the addition of an anti-NKG2D antibody inhibited cytolysis by 50%. However, human bone marrow stromal cells can reduce CIK and CIK/MV mediated killing of myeloma cells (RPMI 8226, JJN-3 and MM1). In vivo, CIK and CIK/MV prolonged the survival of mice with systemic myeloma, although CIK/MV showed enhanced antitumor activity compared with CIK. Irradiation of the KAS-6/1 cells induced mRNA and protein expression of NKG2D ligands, MICA, and MICB in a dose-dependent manner and enhanced delivery of CIK/MV to the irradiated tumors. In both subcutaneous and disseminated myeloma models, XRT at 2 Gy resulted in superior prolongation of the survival of mice given CIK/MV therapy compared with CIK/MV with no XRT. This study demonstrates the potential of CIK against myeloma and that the combination of virotherapy with radiation could be used to further enhance therapeutic outcome using CIK cells.

An organotypic coculture model supporting proliferation and differentiation of medullary thymic epithelial cells and promiscuous gene expression

Understanding intrathymic T cell differentiation has been greatly aided by the development of various reductionist in vitro models that mimic certain steps/microenvironments of this complex process. Most models focused on the faithful in vitro restoration of T cell differentiation and selection. In contrast, suitable in vitro models emulating the developmental pathways of the two major thymic epithelial cell lineages--cortical thymic epithelial cells and medullary thymic epithelial cells (mTECs)--are yet to be developed. In this regard, lack of an in vitro model mimicking the developmental biology of the mTEC lineage has hampered the molecular analysis of the so-called "promiscuous expression" of tissue-restricted genes, a key property of terminally differentiated mTECs. Based on the close biological relationship between the skin and thymus epithelial cell compartments, we adapted a three-dimensional organotypic coculture model, originally developed to provide a bona fide in vitro dermal equivalent, for the culture of isolated mTECs. This three-dimensional model preserves key features of mTECs: proliferation and terminal differentiation of CD80(lo), Aire(-) mTECs into CD80(hi), Aire(+) mTECs; responsiveness to RANKL; and sustained expression of FoxN1, Aire, and tissue-restricted genes in CD80(hi) mTECs. This in vitro culture model should facilitate the identification of molecular components and pathways involved in mTEC differentiation in general and in promiscuous gene expression in particular.

Down syndrome, autoimmunity and T regulatory cells

Autoimmune diseases are more represented in Down syndrome (DS) individuals compared to chromosomally normal people. Natural T regulatory cells (nT(reg) ) have been considered to be primary in the role of controlling the intensity and targets of the immune response. We have investigated the phenotypical and functional alteration of nT(reg) in a group of DS people. The phenotypical characteristic of T(reg) cells of 29 DS was analysed and compared with an age-matched healthy control group. The inhibitory potential of CD4(+) CD25(high) CD127(low) T regulatory cells was evaluated on autologous CD4(+) CD25(-) T cell proliferation in response to activation with a mytogenic pan-stimulus (anti-CD2, anti-CD3 and anti-CD28 antibodies). The CD4(+) CD25(high) cells in the DS and control groups were 2·692±0·3808%, n=29 and 1·246±0·119, n=29%, respectively (P=0.0007), with a percentage of forkhead box protein 3 (FoxP3)-expressing cells of 79·21±3·376%, n=29 and 59·75±4·496%, respectively (P=0.0015). CD4(+) CD25(+) FoxP3(+) cells were increased in peripheral blood from DS subjects (DS mean 5·231±0·6065% n=29, control mean 3·076±0·3140% n=29). The majority of CD4(+) CD25(high) were CD127(low) and expressed a high percentage of FoxP3 (natural T(reg) phenotype). While the proliferative capacity of DS T cells was not altered significantly compared to normal individuals, a reduced inhibitory potential of T(reg) compared to healthy controls was clearly observed (mean healthy control inhibition in T(eff)  : T(reg) 1:1 co-culture: 58·9%±4·157%, n=10 versus mean DS inhibition in T(eff) :T(reg) 1:1 co-culture: 39·8±4·788%, n=10, P=0.0075; mean healthy control inhibition in T(eff)  : T(reg) 1:0·5 co-culture: 45·10±5·858%, n=10 versus DS inhibition in T(eff) : T(reg) 1:0·5 co-culture: 24·10±5·517%, n=10, P=0.0177). DS people present an over-expressed peripheral nT(reg) population with a defective inhibitory activity that may partially explain the increased frequency of autoimmune disease.

The histone deacetylase inhibitor, romidepsin, suppresses cellular immune functions of cutaneous T-cell lymphoma patients

Romidepsin is the second histone deacetylase inhibitor (HDACi) approved for the treatment of advanced stages of cutaneous T-cell lymphoma (CTCL). Recent in vitro data suggest that HDACis suppress immune function although these findings have not been confirmed in patients. Thus, we serially examined the cellular immune function of eight CTCL patients undergoing treatment with three cycles of romidepsin. We measured the patients' natural killer (NK) and dendritic cell (DC) function and performed an in vitro terminal deoxynucleotidyl transferase dUTP nick end labeling assay to measure cellular apoptosis. Patients' NK cell cytolytic activity decreased from baseline to the third cycle of treatment (P = 0.018) but stimulation with a toll-like receptor (TLR) agonist increased this activity (P = 0.018). At baseline, a TLR agonist could both activate patients' DC (P = 0.043) and stimulate interleukin-12 protein production (P = 0.043) but both were suppressed after the first cycle of romidepsin. Finally, we observed increased specificity for romidepsin-induced CD4+ tumor cell apoptosis and dose-dependent increases in cellular apoptosis of healthy cells in multiple lineages (P < 0.05). These findings raise concern that HDACis suppress immune function in CTCL patients and they support the concurrent use of multiple immune stimulatory agents to preserve the host immune response.

Induction of cytotoxic T lymphocytes by CEA peptide-pulsed γδ T-cells isolated from patients with advanced cancer

Cytotoxic γδ T-cells recognize antigens directly without the need for antigen processing and presentation. Recently, it was reported that they can also present antigens and proliferate in vitro. In this study, we examined whether γδ T-cells isolated from patients with advanced cancer can be used for immunotherapy. Twenty-two inoperable patients with multiple cancer metastases were enrolled in the study. There was no significant difference in the ratio of γδ T-cells within the peripheral blood mononuclear cell population isolated from healthy volunteers and cancer patients. γδ T-Cells isolated from cancer patients were expanded 2- to 5-fold using zoledronic acid or 2-methyl-3butenyl-1-pyrophosphate and IL-2. Autologous CD8(+) T-cells co-cultured with expanded CEA peptide-pulsed γδ T-cells from cancer patients with HLA-A24 killed more CEA-positive HLA-A24-matched gastric cancer cells and secreted higher levels of interferon-γ. These results suggest that γδ T-cells from cancer patients may be ideal candidates for adoptive immunotherapy.

Pregnancy: tolerance and suppression of immune responses

Presence of foreign tissue in a host's body would immediately lead to a strong immune response directed to destroy the alloantigens present in fetus and placenta. However, during pregnancy, the semiallogeneic fetus is allowed to grow within the maternal uterus due to multiple mechanisms of immune tolerance, which are discussed in this chapter.

Antigenic strength controls the generation of antigen-specific IL-10-secreting T regulatory cells

Administration of peptides i.n. induces peripheral tolerance in Tg4 myelin basic protein-specific TCR-Tg mice. This is characterized by the generation of anergic, IL-10-secreting CD4+ T cells with regulatory function (IL-10 Treg). Myelin basic protein Ac1-9 peptide analogs, displaying a hierarchy of affinities for H-2 A(u) (Ac1-9[4K]<<[4A]<[4Y]), were used to investigate the mechanisms of tolerance induction, focusing on IL-10 Treg generation. Repeated i.n. administration of the highest affinity peptide, Ac1-9[4Y], provided complete protection against EAE, while i.n. Ac1-9[4A] and Ac1-9[4K] treatment resulted in only partial protection. Ac1-9[4Y] was also the most potent stimulus for IL-10 Treg generation. Although i.n. treatment with Ac1-9[4A] gave rise to IL-10-secreting CD4+ T cells, the population as a whole was also capable of secreting IFN-gamma after an in vitro recall response to Ac1-9[4A] or [4Y]. In addition to IL-10 production, other facets of tolerance, namely, anergy and suppression (both in vitro and in vivo), were affinity dependent, with i.n. Ac1-9[4Y]-, [4A]- or [4K]-treated CD4+ T cells being the most, intermediate and least anergic/suppressive, respectively. These findings demonstrate that the generation of IL-10 Treg in vivo is driven by high signal strength.

[Safety of cell culture-based influenza vaccines]

After more than 60 years, the conventional production of influenza vaccines employing fertilized chicken eggs has reached its limits - both in terms of temporal flexibility and vaccine production volume. This situation is compounded by the fact that the present pandemic-driven situation has roughly doubled the overall vaccine demand virtually "overnight". Modem cell culture technology has significant advantages over the conventional method of manufacturing influenza vaccines employing embryonated chicken eggs, and enables manufacturers to respond rapidly to the exploding worldwide seasonal and pandemic-driven need for influenza vaccines. Recent articles in the popular press claiming that cell culture-based influenza vaccines can cause tumours raised uncertainty among physicians and the general population, and also discredit officially accepted assessments and product licensing by the relevant authorities. The present article provides an overview on the cell culture technology and on the safety profile of the cells and of the vaccine product.

[Assessment of in vitro immune response in a young population exposed to atmospheric contamination of Guadalajara]

BACKGROUND

Atmospheric pollutants may cause alterations on health of persons exposed to urban environment.

OBJECTIVE

To evaluate in vitro immunological response in young population exposed to different levels of atmospheric pollution.

PARTICIPANTS AND METHODS

The study was performed in two groups of young men, one from Guadalajara, and the other from Tlajomulco. The volunteers had to be healthy and without precedents of atopia. The immunological responses studied on PBMC were: stimulation index by timidin incorporation, CD25 expression by flow citometry, and production of citokines IL-2 and IL-4 by ELISAtest. Atmospheric parameters monitored were: NO2, O3, SO2, CO and PM10.

RESULTS

In Guadalajara the concentrations of NO2 and PM10 exceeded in 30% and 40%, respectively, the index established by WHO. Stimulation index of PBMC of the young men to Guadalajara was 18 +/- 4, whereas that of the volunteers from Tlajomulco was 23 +/- 3. Expression of CD25 did not show a significant difference between studied groups. IL-2 and IL-4 levels were similar between the young men of the city and those from the rural area.

CONCLUSION

The environmental pollution in Guadalajara did not modify in a significant way proliferation, CD25 expression, nor secretion of IL-2 and IL-4 on PBMC. This demonstrates that healthy young men are less susceptible than other groups to the alterations caused by exposure to moderate levels of atmospheric pollutants.

Human T lymphocyte migration towards the supernatants of human rhinovirus infected airway epithelial cells: influence of exercise and carbohydrate intake

Physical stress induces a marked redistribution of T lymphocytes that may be influenced by carbohydrate (CHO) availability, yet the effect of these on T lymphocyte migration towards infected tissue is unknown. Therefore, the aim of this study was to determine the effect of strenuous exercise and CHO ingestion on subsequent ex vivo lymphocyte migration towards the supernatants of a Human Rhinovirus (HRV)-infected bronchial epithelial cell line. In a randomised, cross-over, double-blind design, 7 trained males ran for 2 h at 60% VO2peak on two occasions with regular ingestion of either a 6.4% w/v glucose and maltodextrin solution (CHO trial) or placebo solution (PLA trial). Plasma glucose concentration was higher on CHO than PLA after exercise (P<0.05). Migration of CD4+ and CD8+ cells and their CD45RA+ and CD45RO+ subpopulations towards supernatants from HRV-infected cells decreased following exercise (main effect for exercise, P<0.01 for CD4+, CD4+CD45RA+ and CD4+CD45RO+; P<0.05 for CD8+, CD8+CD45RA+ and CD8+CD45RO+). Migration of CD4+ cells and CD4+CD45RA+ cells was approximately 35% and approximately 30% higher, respectively, on CHO than PLA at 1 h post-exercise (interaction, P<0.05 for both) and was higher on CHO than PLA for all other subpopulations (P<0.05, main effect for trial). There was little effect of exercise or CHO on migration of these cells towards uninfected (control) cell supernatants or on the proportion of these cells within the peripheral blood mononuclear cell population. The findings of this study suggest that physical stress reduces T cell migration towards HRV-infected cell supernatants and that ingestion of CHO can lessen this effect.

Immune system alterations in patients with inflammatory bowel disease during remission

OBJECTIVE

Perturbed immune homeostasis elicited by misbalanced production of proinflammatory and anti-inflammatory cytokines is characteristic of inflammatory bowel disease. The aim of this study was to evaluate cytokine profile in patients with different forms of inflammatory bowel disease - ulcerative colitis and Crohn's disease - during clinical remission phase.

MATERIAL AND METHODS

Production of proinflammatory Th1 cytokines (tumor necrosis factor-alpha (TNF-alpha), interferon-gamma (IFN-gamma)) and anti-inflammatory Th2 cytokines (interleukin-10 (IL-10) and interleukin-13 (IL-13)) was analyzed in peripheral blood mononuclear cells of patients with inflammatory bowel disease (9 with ulcerative colitis and 9 with Crohn's disease) and control subjects (n=11) by enzyme-linked immunosorbent assay (two-site ELISA).

RESULTS

The results of the study revealed that the level of TNF-alpha after stimulation with phytohemagglutinin in patients with Crohn's disease was significantly higher in comparison to both patients with ulcerative colitis and controls (P<0.001 and P<0.01, respectively). The secretion of IFN-gamma both in patients with Crohn's disease and ulcerative colitis was lower than that in controls (P=0.05 and P<0.01, respectively), but it normalized after stimulation with phytohemagglutinin. The levels of IL-10 and IL-13 were significantly (P<0.01) higher in patients with Crohn's disease than in patients with ulcerative colitis and control group before and after stimulation with phytohemagglutinin.

CONCLUSIONS

The results of our study provide evidence that in patients with inflammatory bowel disease, the imbalance between production of proinflammatory Th1 and anti-inflammatory Th2 cytokines persists even during remission of the disease, and disturbances of immune homeostasis are significantly more expressed in patients with Crohn's disease than in patients with ulcerative colitis.

Polarization of natural killer T cells towards an NKT2 subpopulation occurs after stimulation with alpha-galactosylceramide and rhG-CSF in aplastic anemia

Natural killer T (NKT) cells play an important role in the regulation of immune responses in a broad range of diseases, including autoimmune disorders, infectious diseases and cancer. So far, few studies have evaluated the roles of NKT cells in the pathogenesis of aplastic anemia (AA), an autoimmune disease. In this study, we investigated the quantitative and qualitative changes in NKT cells in bone marrow (BM) mononuclear cells of AA patients in response to in vitro stimulation with alpha-galactosylceramide. Compared to healthy controls, BM from AA patients had reduced fraction of NKT cells, which possessed a decreased potential to expand in vitro in response to alpha-galactosylceramide stimulation, producing more IFNgamma+ NKT1 cells. In the presence of rhG-CSF, the expansion capacity of NKT cells stimulated by alpha-galactosylceramide was significantly reduced in both AA and control groups, with the majority of the activated NKT cells expressing intracellular IL-4, and the fractions of IFNgamma+ NKT cells were significantly reduced. In summary, our results indicate that polarization of NKT cells towards the NKT2 subpopulation occurs after co-stimulation with alpha-galactosylceramide and rhG-CSF in AA.

Quantitative measurement of pathogen-specific human memory T cell repertoire diversity using a CDR3 beta-specific microarray

Background

Providing quantitative microarray data that is sensitive to very small differences in target sequence would be a useful tool in any number of venues where a sample can consist of a multiple related sequences present in various abundances. Examples of such applications would include measurement of pseudo species in viral infections and the measurement of species of antibodies or T cell receptors that constitute immune repertoires. Difficulties that must be overcome in such a method would be to account for cross-hybridization and for differences in hybridization efficiencies between the arrayed probes and their corresponding targets. We have used the memory T cell repertoire to an influenza-derived peptide as a test case for developing such a method.

Results

The arrayed probes were corresponded to a 17 nucleotide TCR-specific region that distinguished sequences differing by as little as a single nucleotide. Hybridization efficiency between highly related Cy5-labeled subject sequences was normalized by including an equimolar mixture of Cy3-labeled synthetic targets representing all 108 arrayed probes. The same synthetic targets were used to measure the degree of cross hybridization between probes. Reconstitution studies found the system sensitive to input ratios as low as 0.5% and accurate in measuring known input percentages (R² = 0.81, R = 0.90, p < 0.0001). A data handling protocol was developed to incorporate the differences in hybridization efficiency. To validate the array in T cell repertoire analysis, it was used to analyze human recall responses to influenza in three human subjects and compared to traditional cloning and sequencing. When evaluating the rank order of clonotype abundance determined by each method, the approaches were not found significantly different (Wilcoxon rank-sum test, p > 0.05).

Conclusion

This novel strategy appears to be robust and can be adapted to any situation where complex mixtures of highly similar sequences need to be quantitatively resolved.

IL-10-inducing adjuvants enhance sublingual immunotherapy efficacy in a murine asthma model

BACKGROUND

IL-10-inducing adjuvants could enhance the efficacy of allergy vaccines in establishing allergen-specific tolerance. The aim of this study was to identify such adjuvants using in vitro cultures of human and murine cells and to evaluate them in a therapeutic murine model of sublingual immunotherapy (SLIT).

METHODS

Adjuvants stimulating IL-10 gene expression by human or murine immune cells were tested sublingually in BALB/c mice sensitized to ovalbumin (OVA), assessing the reduction in airway hyperresponsiveness (AHR) by whole-body plethysmography. The induction of regulatory T cells (T(reg)) was evaluated using phenotypic and functional assays. T-cell proliferation in cervical lymph nodes (LNs) was assessed following intravenous transfer of CFSE-labelled OVA-specific T cells and FACS analysis.

RESULTS

A combination of 1,25-dihydroxyvitamin D3 plus dexamethasone (VitD3/Dex) as well as Lactobacillus plantarum were found to induce IL-10 production by human and murine dendritic cells (DCs). The former inhibits LPS-induced DC maturation, whereas L. plantarum induces DC maturation. Following stimulation with VitD3/Dex-pretreated DCs, CD4+ naïve T cells exhibit a T(reg) profile. In contrast, a Th1/T(reg) pattern of differentiation is observed in the presence of DCs treated with L. plantarum. Both adjuvants significantly enhance SLIT efficacy in mice, in association with either induction of Foxp3+ T(reg) cells (for VitD3/Dex) or proliferation of OVA-specific T cells in cervical LNs (for L. plantarum).

CONCLUSIONS

Both VitD3/Dex and L. plantarum polarize naïve T cells towards IL-10-expressing T cells, through distinct mechanisms. As adjuvants, they both enhance SLIT efficacy in a murine asthma model.

Prevention of human PC-346C prostate cancer growth in mice by a xenogeneic tissue vaccine

Vaccination, as an approach to prostate cancer, has largely focused on immunotherapy utilizing specific molecules or allogeneic cells. Such methods are limited by the focused antigenic menu presented to the immune system and by immunotolerance to antigens recognized as "self". To examine if a xenogeneic tissue vaccine could stimulate protective immunity in a human prostate cancer cell line, a vaccine was produced by glutaraldehyde fixation of harvested PAIII prostate cancer cells tumors (GFT cell vaccine) from Lobund-Wistar rats. Immunocompetent Ncr-Foxn1 mice were vaccinated with the GFT cell vaccine four times, 7 days apart. The control animals were either not vaccinated or vaccinated with media or glutaraldehyde-fixed PC346C human prostate cancer cells and adjuvant. About 8 days after the final boost, serum and spleens were harvested. The splenocytes were co-incubated with PC346C cells and then transplanted orthotopically into sygneneic immunodeficient nude mice. About 10 weeks later, the prostates were weighed and sampled for histolologic examination. The spleens were harvested from additional mice, and the splenocytes were cultured, either with or without pulsing by GFT cells, and the supernatants harvested 72 h later for cytokine analysis. Results showed that vaccination with GFT cells resulted in increased serum antibody to a PAIII cell lysate; reduced weight of the prostate/seminal vesicle complex and reduced incidence of prostate cancer in nude mice; increased splenocyte supernatant levels of TNF-alpha, IL-2, IFN-gamma and IL-12, cytokines associated with Th1 immunity; and increased splenocyte supernatant levels of IL-4 and IL-10, cytokines associated with Th2 immunity. In summary, the results suggest that use of a xenogeneic tissue vaccine can stimulate protective immunity against human prostate cancer cells.

An MVA vaccine overcomes tolerance to human p53 in mice and humans

BACKGROUND

The cellular regulatory protein p53 is overexpressed by almost 50% of all malignancies making it an attractive target for a vaccine approach to cancer. A number of immunotherapy approaches targeting p53 have been evaluated successfully in murine models, but translation of these preclinical findings to the clinic has been unsuccessful. Prior studies in our laboratory employing murine models demonstrated that a modified vaccinia virus Ankara (MVA) vaccine expressing murine p53 could stimulate p53 specific immunity. Systemic administration of the MVA vaccine was able to effect the rejection of established tumors. To better understand the immunologic mechanisms that underlie the vaccine function of human p53, we utilized a murine model in which the murine germ line copy of p53 was replaced with a modified human one. These mice, referred to as Hupki, were evaluated as a tolerant model to explore the capacity of MVA expressing human p53 to overcome tolerance and reject human p53-expressing tumors.

RESULTS

MVAp53 immunization of Hupki mice resulted in the generation of p53-specific CD8(+) T cells and the rejection of a highly aggressive murine mammary carcinoma cell line 4T1(H-2d) transfected with human p53 (4T1p53). An immunologic correlate of tumor protection was evaluated utilizing an overlapping peptide library spanning the full length of human p53. This reagent was also used in combination with MVAp53 to stimulate p53-specific CD8(+) T cell responses in cancer patients.

CONCLUSION

These studies demonstrate the potential of MVAp53 to overcome tolerance to p53 for cancer immunotherapy.

Role of tumor endothelium in CD4+ CD25+ regulatory T cell infiltration of human pancreatic carcinoma

BACKGROUND

Regulatory T (Treg) cells have been detected in human carcinomas and may play a role in preventing the rejection of malignant cells.

METHODS

We quantified Treg cells and the expression of the addressins and the respective ligands that attract them in blood and in human pancreatic tumors and adjacent nonmalignant tissues from 47 patients. The capacity of Treg cells to adhere to and transmigrate through autologous endothelial cells was tested in vitro using spheroid adhesion assays and in vivo using a xenotransplant NOD/SCID model and in the presence and absence of antibodies to addressins. All statistical tests were two-sided.

RESULTS

More Treg cells infiltrated pancreatic carcinomas than adjacent nonmalignant pancreatic tissues (120 cells per mm2 versus 80 cells per mm2, difference = 40 cells per mm2, 95% confidence interval [CI] = 21.2 cells per mm2 to 52.1 cells per mm2; P<.001). In contrast to conventional CD4+ T cells, more blood-derived Treg cells adhered to (1.0% versus 5.2%, difference = 4.2%, 95% CI = 2.7% to 5.6%; P<.001) and transmigrated through (3332 cells versus 4976 cells, difference = 1644 cells, 95% CI = 708 cells to 2580 cells; P = .008) autologous tumor-derived endothelial cells in vitro and in vivo (458 cells versus 605 cells, difference = 147 cells, 95% CI = 50.8 to 237.2 cells; P = .04). Tumor-derived endothelial cells expressed higher levels of addressins--including mucosal adressin cell adhesion molecule-1 (MAdCAM-1), vascular cell adhesion molecule-1 (VCAM-1), CD62-E, and CD166--than endothelial cells from normal tissue. Experiments using antibodies to addressins showed that transmigration was mediated by interactions of addressins, including MAdCAM-1, VCAM-1, CD62-E, and CD166 with their respective ligands, beta7 integrin, CD62L, and CD166, which were expressed specifically on Treg cells.

CONCLUSIONS

Tumor-induced expression of addressins on the surface of endothelial cells allows a selective transmigration of Treg cells from peripheral blood to tumor tissues.

[mRNA-transfected dendritic cells: a promising strategy in immunotherapy]

Dendritic cells play a central role in the initiation of the immune response as they are the only antigen-presenting cells able to prime naive T cells. This makes the dendritic cells the vector of choice to use as a cell-based vaccine in immunotherapy. Although there are several strategies to deliver antigen to dendritic cells, the ones transfected with mRNA coding for tumor or viral antigens are able to induce potent antigen specific T-cell responses directed against multiple epitopes. In this review, we report several advances made in the field of anti-tumoral and anti-HIV immunotherapy using mRNA-transfected dendritic cells-based approaches.

CTLA-4 ablation and interleukin-12 driven differentiation synergistically augment cardiac pathogenicity of cytotoxic T lymphocytes

CD8+ cytotoxic T lymphocytes contribute to viral and autoimmune myocarditis and cardiac allograft rejection. The role of cytotoxic T-lymphocyte-associated antigen (CTLA)-4 as a negative regulator of CD4+ T cells is well defined, yet CTLA-4 regulation of CD8+ T cells is less clear. We studied CTLA-4 regulation of cytotoxic T lymphocytes in a transgenic model of CD8+ T-cell-mediated myocarditis. We generated CTLA-4(-/-) Rag 2(-/-) OT-1 mice, the CD8+ T cells of which express an ovalbumin (OVA) peptide-specific, class I major histocompatibility complex-restricted T-cell receptor. CTLA-4(-/-Tc12) OT-1 effectors, differentiated with interleukin-12 present, are hyperproliferative in vitro, compared with CTLA-4(+/+)Tc12 OT-1 controls. Transfer of low doses of CTLA-4(-/-Tc12) OT-1 cells to cMy-mOVA mice, which express OVA on cardiac myocytes, causes severe myocarditis, with 99% mortality, compared with no mortality after transfer of low doses of CTLA-4(+/+)Tc12 OT-1 cells. High doses of CTLA-4(+/+)Tc12 cells cause lethal myocarditis in cMy-mOVA mice, but high doses of CTLA-4(+/+)Tc0 CTL, generated without interleukin-12, are hypoproliferative within the cardiac-draining lymph node and do not significantly infiltrate the heart. In contrast, CTLA-4(-/-Tc0) cytotoxic T lymphocytes do proliferate in the cardiac-draining lymph node and diffusely infiltrate the heart. Nonetheless, high doses of CTLA-4(-/-Tc0) cells cause only limited tissue damage, and the disease is not lethal. These data show that CTLA-4 regulates myocarditic CD8+ T cell responses and that CTLA-4 deficiency partly overcomes a differentiation block that exists when naïve CD8+ T cells are stimulated without interleukin-12. Therefore, targeting CTLA-4 solely or in conjunction with interleukin-12 could influence effector CD8+ T cell responses in therapeutically beneficial ways.

Farnesyltransferase inhibitors inhibit T-cell cytokine production at the posttranscriptional level

Several cytoplasmic proteins, such as GTPases of the Ras family, containing a C-terminal CAAX motif are prenylated by farnesyltransferase to facilitate localization to cellular membranes where activation occurs. Farnesyltransferase inhibitors (FTIs) interfere with this farnesylation process, thereby preventing proper membrane localization and rendering the proteins unavailable for activation. Currently, FTIs are being explored as antineoplastic agents for the treatment of several malignancies. However, since farnesylated proteins like Ras are also involved in intracellular signaling in lymphocytes, FTIs might interfere with T-cell activation. Based on this hypothesis we examined the effect of several FTIs on cytokine production in response to anti-CD3 + anti-CD28 monoclonal antibodies or PMA + ionomycin. Murine Th1 and Th2 clones, stimulated in the presence of FTIs, showed a dose-dependent reduction of lineage-specific cytokine secretion (IFN-gamma, IL-2, IL-4, IL-5). However, no inhibition of ERK or JNK MAP kinases was observed, nor was induction of cytokine mRNA affected. Rather, intracellular cytokine protein synthesis was blocked. Inhibition of human T-cell INF-gamma production also was observed, correlating with reduced phosphorylation of p70S6K. These results indicate that FTIs inhibit T-cell activation at the posttranscriptional level and also suggest that they may have potential as novel immunosuppressive agents.

Rapid and strong induction of apoptosis in human eosinophils by anti-CD30 mAb-coated microspheres and phagocytosis by macrophages

BACKGROUND

Eosinophils represent a potential therapeutic target in allergic diseases. We previously reported that two clones of anti-CD30 mAbs (HRS-4 and Ber-H8) induced extremely rapid and intense apoptosis in human eosinophils in vitro, but only when the mAbs were immobilized on plates [Matsumoto K, J Immunol 2004;172:2186]. As the initial step towards clinical application of these anti-CD30 mAbs in the treatment of allergic diseases, we made an attempt to clarify two issues; first, whether or not anti-CD30 mAb-coated microspheres can efficiently induce apoptosis in human eosinophils, and second, whether or not these apoptotic eosinophils can be phagocytosed by macrophages without the release of granular proteins.

METHODS

Purified human eosinophils were treated with anti-CD30 mAb-coated polystyrene microspheres (diameter, 1.44 mum). Apoptosis was determined by annexin V-binding. For the phagocytosis assay, eosinophils were co-cultured with monocyte-derived human macrophages or PMA-pretreated U-937 cells. Phagocytosis was determined by light microscopy and by the eosinophil-derived neurotoxin (EDN) concentration in the supernatant.

RESULTS

Anti-CD30 mAb-coated, but not control IgG1-coated microspheres significantly reduced eosinophil survival in a dose-dependent manner. Marked phagocytosis of the apoptotic eosinophils by macrophages was also observed when the eosinophils were treated with anti-CD30 mAb-coated microspheres. The apoptotic eosinophils released large amounts of EDN in the absence of macrophages; however, the EDN levels were significantly decreased when the eosinophils were co-cultured with macrophages.

CONCLUSIONS

Anti-CD30 mAb-coated microspheres are capable of inducing rapid and strong apoptosis in human eosinophils. Furthermore, the apoptotic eosinophils were also phagocytosed by macrophages with minimal release of the granular proteins.

IgE- and FcepsilonRI-mediated enhancement of surface CD69 expression in basophils: role of low-level stimulation

Surface-expressed CD69 is a recently recognized activation marker for basophils and is reported to be strongly induced in vitro by IL-3. In this study, we investigated whether IgE- and high-affinity receptor for IgE (FcepsilonRI)-dependent stimuli can affect basophil CD69 expression. Highly purified basophils were cultured for 24 h in the presence of anti-FcepsilonRI alpha-chain mAb, CRA-1 and IL-3, and surface CD69 expression was analyzed by flow cytometry. CRA-1 mAb at 1 ng/ml or lower concentrations, levels too low to provoke direct histamine release, dose-dependently enhanced surface CD69 expression in the presence of IL-3, although low-dose CRA-1 mAb failed to induce CD69 expression in the absence of IL-3. Recombinant Der f 2 at 10 to 100 pg/ml enhanced CD69 levels in the presence of IL-3 in basophils from mite-sensitive subjects. These results suggest that allergens may influence basophil CD69 expression even when the levels of the antigens are too low to trigger direct degranulation. Upregulated CD69 expression on locally accumulated basophils in bronchial asthma may be attributed at least in part to a combination of local cytokines, especially IL-3, plus exposure to low levels of IgE-crosslinking allergens.

IL-2-induced IL-9 production by allergen-specific human helper T-cell clones

BACKGROUND

IL-9 is an important cytokine in allergic diseases such as asthma, atopic dermatitis, etc. T helper (Th) cells seem to be the main source of IL-9. Cellular and molecular mechanisms of IL-9 production by human Th cells have been poorly understood.

METHODS

Dermatophagoides farinae(Der f)-specific Th clones were established from peripheral blood lymphocytes of atopic asthmatics, and cytokine synthesis in response to various stimuli was determined by specific ELISAs.

RESULTS

IL-9 was produced by 14 of 27 human Th clones upon T cell receptor (TCR) stimulation, immobilized anti-CD3 antibody (Ab). IL-9 production was significantly enhanced by the addition of anti-CD28 Ab into the culture, indicating the role of costimulatory signal on IL-9 synthesis. Pharmacologically, IL-9 production was induced by ionomycin (IOM) alone, and enhanced by phorbol 12-myristate 13-acetate (PMA). rIL-2 induced IL-9 production by 8 out of 19 Th clones. IL-9 production by Th clones stimulated with immobilized anti-CD3 Ab was significantly suppressed by the addition of anti-IL-2 neutralizing Ab into the culture.

CONCLUSION

Approximately half of the Der f-specific Th clones derived from atopic asthmatics produced IL-9 upon TCR stimulation. Ca(2+) signal, CD28 signal, and IL-2 receptor signal seem to play important roles in IL-9 production by human Th cells. Moreover, synthesis of IL-9, a Th2 cytokine, is dependent on IL-2, a Th1 cytokine, which is produced by Th cells themselves.

Abnormality of CD4(+)CD25(+) regulatory T cells in idiopathic thrombocytopenic purpura

OBJECTIVES

The aim of this study was to explore the profile and function of CD4(+)CD25(+) regulatory T cells (Treg cells) in idiopathic thrombocytopenic purpura (ITP) patients.

METHODS

Treg cell numbers were analyzed by flow cytometric analysis in peripheral blood mononuclear cells collected from healthy donors or patients with ITP. Quantification of cell proliferation was assayed by an enzyme-linked immunosorbent assay kit, based on the measurement of BrdU incorporation during DNA synthesis.

RESULTS

The percentage of Treg cells was significantly decreased in ITP patients in active and non-remission state(5.79 +/- 1.22%) when compared with the patients in remission(11.63 +/- 4.56%) and to healthy subjects(12.68 +/- 3.59%). The suppressive activity of Treg cells in ITP patients was also found to be impaired.

CONCLUSION

These results suggest that decreased number and function of Treg cells might be one of mechanisms that cause immune regulation dysfunction in ITP.

Human embryonic stem cells are immunogenic in allogeneic and xenogeneic settings

Recent studies have suggested that human embryonic stem cells (HESC) are immune-privileged and may thereby circumvent rejection. The expression of immunologically active molecules was studied by DNA microarray analysis and by flow cytometry. HESC were transplanted into immunologically competent mice and traced by fluorescence in-situ hybridization (FISH) and immunohistochemistry. The ability of HESC to directly and indirectly induce immune responses in CD4+ T-cells from naive and transplanted mice was studied. Their ability to induce immune responses of human CD4+ T-cells, when cultured in the presence of dendritic cells (DC) syngeneic to responder T-cells, was also analysed. HESC demonstrated expression of HLA class I and HLA class II genes, but the cell surface expression of HLA class II molecules was low even after incubation with IFNgamma. In wild-type mice, HESC could be demonstrated by FISH until 3 days after transplantation and were surrounded by heavy infiltrates of T-cells and macrophages. HESC induced a similar immune response as human fibroblast cells (HFib) on naive and immunized T-cells, both directly and in the presence of syngeneic DC. A similar response was observed in the allogeneic setting. It is concluded that HESC are immunologically inert and do not inhibit immune responses during direct or indirect antigen presentation, and they were acutely rejected in a xenogeneic setting.

Functional and phenotypic characterization of CD8+CD28+ and CD28- T cells in atopic individuals sensitized to Dermatophagoides pteronyssinus

BACKGROUND

CD8+ T suppressor cells may play a role in immunoregulation. Recent studies have characterized this population by the lack of the CD28 molecule. These CD8+CD28 T cells differ phenotypically and functionally from CD8 + CD28 + T cells. Little is known about CD8 + CD28 cells in atopy. Our aim was to analyze the phenotype and functional properties of CD8 + CD28T cells in atopic and non-atopic individuals.

METHODS

Peripheral blood mononuclear cells (PBMC) were obtained after density gradient centrifugation. CD8 + CD28 and CD8 + CD28 + T cells were isolated using immunomagnetic beads. Relative percentages of these cells and expression of several phenotypic markers were analyzed by flow cytometry. Proliferation was assessed by thymidine incorporation in isolated populations and in co-cultures with PBMC using Dermatophagoides pteronyssinus as stimulus. Cytokine synthesis was evaluated in culture supernatants by cytometric bead array.

RESULTS

The relative percentages of CD8+CD28 T cells and their phenotypic expression in atopic and non-atopic volunteers were not significantly different. However, CD8 + CD28 T cells showed greater proliferation than did CD8+CD28+ T cells when stimulated with D. pteronyssinus, although cytokine synthesis patterns were similar. CD8+CD28 co-cultures with PBMC showed greater proliferation than CD8+CD28+ T cell co-cultures, but cytokine synthesis patterns were not different.

CONCLUSIONS

Our data confirm phenotypic and functional differences between CD28+ and CD28 T cells, irrespective of atopic status. Purified human CD8+CD28 T cells, freshly isolated from peripheral blood, do not have suppressor properties on allergen-specific proliferation or on cytokine synthesis in PBMC.

Efficiency of T-cell receptor expression in dual-specific T cells is controlled by the intrinsic qualities of the TCR chains within the TCR-CD3 complex

Genetic engineering of T lymphocytes is an attractive strategy to specifically redirect T-cell immunity toward viral infections and malignancies. We previously demonstrated redirected antileukemic reactivity of cytomegalovirus (CMV)–specific T cells by transfer of minor histocompatibility antigen HA-2–specific T-cell receptors (TCRs). HA-2–TCR-transferred CMV-specific T cells were potent effectors against HA-2–expressing leukemic cells, as well as CMV-expressing cells. Functional activity of these T cells correlated with TCR cell-surface expression. In the present study we analyzed which properties of transferred and endogenous TCRs are crucial for efficient cell-surface expression. We demonstrate that expression of the introduced TCR is not a random process but is determined by characteristics of both the introduced and the endogenously expressed TCR. The efficiency of TCR cell-surface expression is controlled by the intrinsic quality of the TCR complex. In addition, we demonstrate that chimeric TCRs can be formed and that efficiency of TCR expression is independent of whether TCRs are retrovirally introduced or naturally expressed. In conclusion, introduced, endogenous, and chimeric TCRs compete for cell-surface expression in favor of the TCR-CD3 complex with best-pairing properties.

Targeting the activation-induced antigen CD137 can selectively deplete alloreactive T cells from antileukemic and antitumor donor T-cell lines

In HLA-incompatible hematopoietic stem cell transplantation, alloreactive donor T cells recognizing recipient mismatch HLA cause severe graft-versus-host disease (GVHD). Strategies allowing the selective depletion of alloreactive T cells as well as the enhancement of graft-versus-malignancy immunity would be beneficial. We generated donor CD8 T-cell lines in vitro using allogeneic recipient cells mismatched at a single HLA class I allele or haplotype as stimulators. Recipient cells were obtained from acute myeloid leukemias, renal-cell carcinomas, and CD40L-induced B lymphoblasts. Resulting alloreactive T cells were activated by incubating day 21 T-cell cultures with HLA-mismatch transfected K562 cells or recipient-derived fibroblasts. Selective allodepletion (SAD) was subsequently performed by a newly developed immunomagnetic depletion approach targeting the tumor necrosis factor receptor molecule CD137 (4-1BB). Compared with other activation-induced antigens, CD137 showed a superior performance based on a consistently low baseline expression and a rapid up-regulation following alloantigen stimulation. In 15 different SAD experiments, the frequency of alloreactive CD8 T cells was reduced to a median of 9.5% compared with undepleted control populations. The allodepleted T-cell subsets maintained significant antitumor and antiviral CD8 responses. In vitro expansion of tumor-reactive T cells followed by CD137-mediated SAD might enhance the antitumor efficacy of T-cell allografts with lower risk of inducing GVHD.

Effects of sivelestat, a new elastase inhibitor, on IL-8 and MCP-1 production from stimulated human alveolar epithelial type II cells

PURPOSE

The alveolar epithelial cell type II (AEC-II) is itself able to amplify lung inflammation by producing inflammatory cytokines and chemokines, leading to the activation and recruitment of phagocytes. Sivelestat, a new neutrophil elastase inhibitor, has been shown to attenuate acute lung injury in animal experiments. In the current study, we assessed the effects of sivelestat on the production of chemokines from cultured A549 cells, a human AEC-II-like cell line.

METHODS

A549 cells were stimulated with endotoxin or tumor necrosis factor-alpha in the presence of sivelestat (1-100 microg x ml(-1)). Culture supernatant levels of interleukin-8 (IL-8) and monocyte chemoattractant protein-1 (MCP-1) were determined by enzyme-linked immunosorbent assay. The expression of IL-8 and MCP-1 mRNAs in stimulated A549 cells in the presence of sivelestat (100 microg x ml(-1)) was quantified by real-time polymerase chain reaction.

RESULTS

Sivelestat, at 100 microg x ml(-1) reduced the accumulation of IL-8 and MCP-1 in the culture medium. The high dose of sivelestat significantly inhibited the expression of IL-8 mRNA in A549 cells. The drug also decreased MCP-1 mRNA expression, although not significantly.

CONCLUSION

These data suggest that a high dose of sivelestat regulates the production of IL-8 and MCP-1 in AEC-II.

Vaccination of melanoma patients using dendritic cells loaded with an allogeneic tumor cell lysate

The aim of the present phase I/II study was to evaluate the safety, immune responses and clinical activity of a vaccine based on autologous dendritic cells (DC) loaded with an allogeneic tumor cell lysate in advanced melanoma patients. DC derived from monocytes were generated in serum-free medium containing GM-CSF and IL-13 according to Good Manufacturing Practices. Fifteen patients with metastatic melanoma (stage III or IV) received four subcutaneous, intradermal, and intranodal vaccinations of both DC loaded with tumor cell lysate and DC loaded with hepatitis B surface protein (HBs) and/or tetanus toxoid (TT). No grade 3 or 4 adverse events related to the vaccination were observed. Enhanced immunity to the allogeneic tumor cell lysate and to TAA-derived peptides were documented, as well as immune responses to HBs/TT antigens. Four out of nine patients who received the full treatment survived for more than 20 months. Two patients showed signs of clinical response and received 3 additional doses of vaccine: one patient showed regression of in-transit metastases leading to complete remission. Eighteen months later, the patient was still free of disease. The second patient experienced stabilization of lung metastases for approximately 10 months. Overall, our results show that vaccination with DC loaded with an allogeneic melanoma cell lysate was feasible in large-scale and well-tolerated in this group of advanced melanoma patients. Immune responses to tumor-related antigens documented in some treated patients support further investigations to optimize the vaccine formulation.

Regulation of naive T cell function by the NF-kappaB2 pathway

T cell activation involves the orchestration of several signaling pathways, including that of the 'classical' transcription factor NF-kappaB components NF-kappaB1-RelA. The function of the 'nonclassical' NF-kappaB2-RelB pathway is less clear, although T cells lacking components of this pathway have activation defects. Here we show that mice deficient in NF-kappaB-inducing kinase have a complex phenotype consisting of immunosuppression mediated by CD25(-)Foxp3(-) memory CD4(+) cells and, in the absence of those cells, hyper-responsive naive CD4(+) T cells, which caused autoimmune lesions after adoptive transfer into hosts deficient in recombination-activating genes. Biochemical studies indicated involvement of a cell-intrinsic mechanism in which NF-kappaB2 (p100) limits nuclear translocation of NF-kappaB1-RelA and thereby functions as a regulatory 'brake' for the activation of naive T cells.

Human dendritic cells following Aspergillus fumigatus infection express the CCR7 receptor and a differential pattern of interleukin-12 (IL-12), IL-23, and IL-27 cytokines, which lead to a Th1 response

Aspergillus fumigatus is the most prevalent airborne fungal pathogen and causes fatal invasive aspergillosis in immunocompromised patients. Given the essential role of dendritic cells (DC) in initiating and regulating immune responses, we investigated the impact of A. fumigatus conidial infection on human DC. A. fumigatus conidia were rapidly internalized and induced the release of tumor necrosis factor alpha within the first 8 h. After A. fumigatus infection, the majority of DC underwent full maturation, although CCR7 expression was observed only in DC that had internalized the conidia. Additionally, the analysis of regulatory cytokines showed that infected DC simultaneously produced interleukin-12p70 (IL-12p70) and significant amounts of IL-10. IL-10 neutralization was not able to further increase IL-12p70 production from infected DC. Whereas the central role of IL-12 in the generation of Th1 cells has long been appreciated, recently two other members of the IL-12 family, IL-23 and IL-27, were reported to play important roles in the regulation of gamma interferon (IFN-gamma) production from naïve and memory T cells. A. fumigatus-infected DC were also able to express high levels of IL-23p19 and low levels of IL-27p28 at later stages of infection. According to this expression pattern, A. fumigatus-infected DC were able to prime IFN-gamma production of naïve T cells. Thus, this study on the expression of the new IL-12 family members controlling the Th1 response sheds light on a novel aspect of the contribution of DC to anti-Aspergillus immunity.

Natural killer cell differentiation driven by Tyro3 receptor tyrosine kinases

Although understanding of the function and specificity of many natural killer (NK) cell receptors is increasing, the molecular mechanisms regulating their expression during late development of NK cells remain unclear. Here we use representational difference analysis to identify molecules required for late NK cell differentiation. Axl protein tyrosine kinase, together with the structurally related receptors Tyro3 and Mer, were essential for NK cell functional maturation and normal expression of inhibitory and activating NK cell receptors. Also, all three receptors were expressed in maturing NK cells, the ligands of these receptors were produced by bone marrow stromal cells, and recombinant versions of these ligands drove NK cell differentiation in vitro. These results collectively suggest that Axl, Tyro3 and Mer transmit signals that are essential for the generation of a functional NK cell repertoire.

IL-21 enhances SOCS gene expression and inhibits LPS-induced cytokine production in human monocyte-derived dendritic cells

Dendritic cells (DCs) play an important role in innate and adaptive immune responses. In addition to their phagocytic activity, DCs present foreign antigens to naïve T cells and regulate the development of adaptive immune responses. Upon contact with DCs, activated T cells produce large quantities of cytokines such as interferon-gamma (IFN-gamma) and interleukin (IL)-21, which have important immunoregulatory functions. Here, we have analyzed the effect of IL-21 and IFN-gamma on lipopolysaccharide (LPS)-induced maturation and cytokine production of human monocyte-derived DCs. IL-21 and IFN-gamma receptor genes were expressed in high levels in immature DCs. Pretreatment of immature DCs with IL-21 inhibited LPS-stimulated DC maturation and expression of CD86 and human leukocyte antigen class II (HLAII). IL-21 pretreatment also dramatically reduced LPS-stimulated production of tumor necrosis factor alpha, IL-12, CC chemokine ligand 5 (CCL5), and CXC chemokine ligand 10 (CXCL10) but not that of CXCL8. In contrast, IFN-gamma had a positive feedback effect on immature DCs, and it enhanced LPS-induced DC maturation and the production of cytokines. IL-21 weakly induced the expression Toll-like receptor 4 (TLR4) and translation initiation region (TIR) domain-containing adaptor protein (TIRAP) genes, whereas the expression of TIR domain-containing adaptor-inducing IFN-beta (TRIF), myeloid differentiation (MyD88) 88 factor, or TRIF-related adaptor molecule (TRAM) genes remained unchanged. However, IL-21 strongly stimulated the expression of suppressor of cytokine signaling (SOCS)-1 and SOCS-3 genes. SOCS are known to suppress DC functions and interfere with TLR4 signaling. Our results demonstrate that IL-21, a cytokine produced by activated T cells, can directly inhibit the activation and cytokine production of myeloid DCs, providing a negative feedback loop between DCs and T lymphocytes.

Interleukin 15-dependent crosstalk between conventional and plasmacytoid dendritic cells is essential for CpG-induced immune activation

The function of interleukin 15 (IL-15) in unmethylated CpG oligodeoxynucleotide (CpG)-induced immune responses remains unknown. Here, in response to CpG, both wild-type and natural killer cell-depleted mice produced IL-12 and became resistant to a lethal dose of Listeria monocytogenes. In contrast, CpG-treated IL-15-deficient mice produced little IL-12 and succumbed to L. monocytogenes. CpG-stimulated conventional dendritic cells (cDCs) were the main producers of both IL-15 and IL-12, but cDCs did not produce IL-12 in the absence of plasmacytoid DCs (pDCs). The cDC-derived IL-15 induced CD40 expression by cDCs. Interaction between CD40 on cDCs and CD40 ligand on pDCs led to IL-12 production by cDCs. Thus, IL-15-dependent crosstalk between cDCs and pDCs is essential for CpG-induced immune activation.

Human brain parenchymal microglia express CD14 and CD45 and are productively infected by HIV-1 in HIV-1 encephalitis

Microglia are endogenous brain macrophages that show distinct phenotypes such as expression of myeloid antigens, ramified morphology, and presence within the neural parenchyma. They play significant roles in a number of human CNS diseases including AIDS dementia. Together with monocyte-derived (perivascular) macrophages, microglia represent a major target of HIV-1 infection. However, a recent report challenged this notion based on findings in SIV encephalitis. This study concluded that perivascular macrophages can be distinguished from parenchymal microglial cells by their expression of CD14 and CD45, and that macrophages, but not microglia, are productively infected in SIV and HIV encephalitis. To address whether parenchymal microglia are productively infected in HIV encephalitis, we analyzed expression of CD14, CD45 and HIV-1 p24 in human brain. Microglia were identified based on their characteristic ramified morphology and location in the neural parenchyma. We found that parenchymal microglia are CD14+ (activated), CD45+ (resting and activated), and constitute approximately two thirds of the p24+ cells in HIV encephalitis cases. These results demonstrate that microglia are major targets of infection by HIV-1, and delineate possible differences between HIVE and SIVE. Because productively infected tissue macrophages serve as the major viral reservoir, these findings have important implications for AIDS.

Conserved residues of the bare lymphocyte syndrome transcription factor RFXAP determine coordinate MHC class II expression

RFXAP is required for the transcriptional regulation of MHC-II genes. Mutations in RFXAP are the genetic basis for complementation group D cases of the bare lymphocyte syndrome (BLS) immunodeficiency. Comparative genomic sequence analysis was conducted and found that only the C-terminal half of the protein is conserved among vertebrates. The C-terminal third of RFXAP, which contained an extensive glutamine-rich tract, could rescue HLA-DR, but not HLA-DQ or HLA-DP expression in a BLS cell line. To understand this phenomenon, a detailed analysis of the role of specific sequences in the C-terminal third of RFXAP with respect to MHC-II regulation was undertaken. Surprisingly, mutation of the conserved glutamine residues had no effect on activity, whereas mutation of hydrophobic and other conserved residues resulted in discoordinate MHC-II isotype expression. Moreover, mutation of potential phosphorylation sites abolished RFXAP activity. The ability of RFXAP mutants to rescue one isotype, but not another was investigated by their ability to form RFX complexes, bind DNA in vivo, recruit CIITA to promoters and to activate a series of chimeric reporter genes. The results suggest that certain RFXAP mutants exaggerate isotype promoter-specific differences and form transcriptionally inefficient activation complexes with factors at the neighboring cis-acting elements. These results show a distinction in factor recognition that is associated with specific MHC-II isotypes and may explain the basis of allele-specific expression differences.