Poor Stimulators Research Articles

Dendritic cells treated with resveratrol during differentiation from monocytes gain substantial tolerogenic properties upon activation.

Resveratrol is a polyphenol that acts on multiple molecular targets important for cell differentiation and activation. Dendritic cells (DCs) are a functionally diverse cell type and represent the most potent antigen-presenting cells of the immune system. In this study, we investigated resveratrol-induced effects on DCs during their differentiation and maturation. Our results show that resveratrol induces DC-associated tolerance, particularly when applied during DC differentiation. Costimulatory molecules CD40, CD80 and CD86 were down-regulated, as was the expression of major histocompatibility complex (MHC) class II molecules. Surface expression of inhibitory immunoglobulin-like transcript 3 (ILT3) and ILT4 molecules was induced, while human leucocyte antigen (HLA)-G expression was not affected. Resveratrol-treated DCs lost the ability to produce interleukin (IL)-12p70 after activation, but had an increased ability to produce IL-10. Such DCs were poor stimulators of allogeneic T cells and had lowered ability to induce CD4(+) T-cell migration. Furthermore, treated cells were able to generate allogeneic IL-10-secreting T cells, but were not competent in inducing FoxP3 expression These tolerogenic effects are probably associated with the effect of resveratrol on multiple molecular targets through which it interferes with DC differentiation and nuclear factor (NF)-kappaB translocation. Our data provide new insights into the molecular and functional mechanisms of the tolerogenic effects that resveratrol exerts on DCs.

Use of Family Care Indicators and Their Relationship with Child Development in Bangladesh

Poor stimulation in the home is one of the main factors affecting the development of children living in poverty. The family care indicators (FCIs) were developed to measure home stimulation in large populations and were derived from the Home Observations for Measurement of the Environment (HOME). The FCIs were piloted with 801 rural Bangladeshi mothers of children aged 18 months. Five subscales were created: 'play activities' (PA), 'varieties of play materials' (VP), 'sources of play materials', 'household books', and 'magazines and newspapers' (MN). All subscales had acceptable short-term reliability. Mental and motor development of the children was assessed on the Bayley Scales of Infant Development and their language expression and comprehension by mothers' report. After controlling for socioeconomic variables, VP and PA independently predicted four and three of the developmental outcomes respectively, and MN predicted both the Bayley scores. The FCI is promising as a survey-based indicator of the quality of children's home environment.

Prospective randomized study for hydrotubation versus no hydrotubation before intrauterine insemination in unexplained infertility

The purpose of the study was to investigate the value of hydrotubation before intrauterine insemination (IUI). In 228 patients with the diagnosis of unexplained infertility, ovarian stimulation was performed before IUI, using 100mg of clomiphine citrate for 5 days from day 3 of the cycle and one ampoule of human menopausal gonadotrophin for 5 days from day 6 of the cycle. Folliculometry and determination of LH concentration in urine were performed daily until LH became positive, then randomization for hydrotubation before IUI versus no hydrotubation was performed. Fifteen patients were cancelled from the study due to poor response or stimulation of three or more follicles. A total of 213 patients were randomized as follows: 103 patients undergoing hydrotubation using 50 ml of saline and 110 patients with no hydrotubation. IUI was performed the following day and ongoing pregnancy occurred in 13 patients (12.6%) in the hydrotubation group and nine patients (8.2%) in the non-hydrotubation group with no significant difference (OR 1.66; 95% CI 0.62-4.63). In conclusion, hydrotubation before IUI does not improve pregnancy rate.

Lack of antibody affinity maturation due to poor Toll-like receptor stimulation leads to enhanced respiratory syncytial virus disease

Lack of antibody affinity maturation due to poor Toll-like receptor stimulation leads to enhanced respiratory syncytial virus disease

Health Workforce Shortage: A Global Crisis

Health Workforce Shortage: A Global Crisis

Tumor Antigen Presentation by Dendritic Cells

Tumor cells are generally regarded as poor stimulators of naive T cells. In contrast, dendritic cells (DCs) are highly specialized in this function, and are therefore likely to be important intermediaries in the process of stimulating T cell responses to tumors. While providing solid evidence that DCs participate in antitumor immunity has proved difficult, several lines of evidence point in this direction. First, animal models involving bone marrow chimeras have shown that cells of hematopoeitic origin are required to elicit T cell responses to whole-tumor vaccines. Second, compared with other cells of hematopoeitic origin, DCs are particularly well-equipped to cross-present exogenous antigens to CD8+ T cells, a critical function if intermediary cells are involved. Third, tumor-infiltrating DCs purified from tumor samples have the capacity to cross-present tumor antigens in vitro. Finally, priming of anti-tumor T cell responses can be abrogated in new in vivo models in which DCs can be specifically depleted. It is therefore significant that DCs in cancer patients are often kept in an immature or dysfunctional state, thereby preventing stimulation of tumor-specific T cells. This review describes the different steps required for DCs to elicit T cell responses to tumor-associated antigens, and highlights processes that are amenable to intervention as therapy. We conclude that effective anti-tumor activity may be dependent on the ability to re-program DCs resident in the host, perhaps even when transferred autologous DCs generated ex vivo are used as vaccines. In this context, recruiting the activity of cells of the innate immune system to condition host DCs may help elicit more effective T cell-mediated responses.

Myeloid Dendritic Cells from Human Cutaneous Squamous Cell Carcinoma Are Poor Stimulators of T-Cell Proliferation

To determine the phenotype and function of myeloid dendritic cells (DCs) from human cutaneous squamous-cell carcinoma (SCC), we studied their surface marker expression and allo-stimulatory potential ex vivo. There were abundant CD11c(+) myeloid DCs, as well as TNF and inducible nitric oxide synthase (iNOS)-producing DCs, in and around SCC tumor nests. Although myeloid DCs from SCC, adjacent non-tumor-bearing skin, and normal skin, were phenotypically similar by flow cytometry, and there was a pronounced genomic signature of mature DCs in SCC, they showed different T-cell stimulatory potential in an allogeneic mixed leukocyte reaction. Myeloid DCs from SCC were less potent stimulators of allogeneic T-cell proliferation than DCs from non-tumor-bearing skin. Culture with a DC-maturing cytokine cocktail (IL-1beta, IL-6, TNF-alpha, and PGE(2)) enhanced stimulatory potential in DCs from non-tumor-bearing skin, whereas SCC-associated DCs remained poor stimulators of T-cell proliferation. The microenvironment associated with SCC showed expression of TGF-beta, IL-10, and VEGF-A, factors capable of suppressing the DC function. These findings indicate that CD11c(+)/HLA-DR(hi) DCs from SCC are mature, but are not potent stimulators of T-cell proliferation compared with phenotypically similar DCs isolated from non-tumor-bearing skin. Identification of mechanisms responsible for suppression of tumor-associated DCs may provide insight into the evasion of immunosurveillance by SCC.

Tumour necrosis factor alpha blockade impairs dendritic cell survival and function in rheumatoid arthritis

ObjectivesTumour necrosis factor alpha (TNFα) blockade is an effective therapy for rheumatoid arthritis (RA). The immunomodulatory effects of TNFα antagonists are thought to contribute to their therapeutic action. This study...

Risk factors for stunting among under-fives in Libya

Stunting is a chronic condition reflecting poor nutrition and health. Our aim was to ascertain major predictors of stunting in children <5 years old in Libya. A nationally representative, cross-sectional, two-stage stratified cluster sample survey enrolled 4549 under-fives from 6707 households. Logistic regression was used to determine individual risk factors in bivariate and multivariate analyses. Anthropometric measurements were available for 4498 children. Among the 929 stunted children (20.7 %), 495 were boys (53.3 %) and 434 were girls (46.5 %). In multivariate analysis, risk factors were young age (1-2 years: OR = 2.32, 95 % CI 1.67, 3.22; 2-3 years: OR = 1.64, 95 % CI 1.22, 2.21), resident of Al-Akhdar (OR = 1.67, 95 % CI 1.08, 2.58), being a boy (OR = 1.28, 95 % CI 1.05, 1.55), having a less educated father (illiterate: OR = 2.10, 95 % CI 1.17, 3.77; preparatory school: OR = 1.71, 95 % CI 1.11, 2.65), poor psychosocial stimulation (no family visits or trips: OR = 1.52, 95 % CI 1.07, 2.16; father rarely/never plays with child: OR = 2.24, 95 % CI 1.20, 4.16), filtered water (OR = 8.45, 95 % CI 2.31, 30.95), throwing garbage in the street (OR = 13.81, 95 % CI 2.33, 81.72), diarrhoea (OR = 1.58, 95 % CI 1.09, 2.29) and low birth weight (OR = 1.8, 95 % CI 1.17, 2.40). Protective factors were older age of father (OR = 0.53, 95 % CI 0.32, 0.90) and water storage (OR = 0.70, 95 % CI 0.54, 0.90). These variables only explained 20 % of cases of stunting. Various multilevel actions are needed to improve nutritional status of under-fives in Libya. At risk-groups include those with young age (1-3 years), resident of Al-Akhdar region, boys, father's low educational level, poor psychosocial stimulation, poor housing environment, diarrhoea and low birth weight.

Tolerogenic dendritic cells actively inhibit T cells through heme oxygenase‐1 in rodents and in nonhuman primates

Clinical translation of dendritic cell (DC)-based cell therapy requires preclinical studies in nonhuman primates (NHPs). The aim of this work was to establish the in vitro conditions for generation of NHP tolerogenic DCs (Tol-DCs), as well as to analyze the molecular mechanisms by which these cells could control an immune response. Two populations of NHP bone marrow-derived DCs (BMDCs) were obtained: adherent and nonadherent. Although both populations displayed a quite similar phenotype, they were very different functionally. We characterized the adherent BMDCs as Tol-DCs that were poor stimulators of T cells and actively inhibited T-cell proliferation, whereas the nonadherent population displayed immunogenic properties in vitro. Interestingly, the anti-inflammatory and immunosuppressive enzyme heme oxygenase-1 (HO-1) was up-regulated in Tol-DCs, compared to the immunogenic BMDCs. We demonstrated that HO-1 mediates the immunosuppressive properties of Tol-DCs in vitro (in NHPs and rats) and that HO-1 is involved in the in vivo tolerogenic effect of Tol-DCs in a rat model of allotransplantation. In conclusion, here we characterized the in vitro generation of NHP Tol-DCs. Furthermore, we showed for the first time that HO-1 plays a role in the active inhibition of T-cell responses by rat and NHP Tol-DCs.

Targeting Lymphoma with Bispecific Antibody-Armed T Cells and their Potential for use in an Allogeneic Setting (41.31)

Abstract Patients with high-risk refractory or relapsed lymphomas face a poor prognosis and limited therapeutic options. Current treatment regimens of chemotherapy with either rituximab (anti-CD20 mAb) or with allogeneic stem cell transplant (alloSCT) yield serious toxicities and high relapse rates. In particular, benefits of alloSCT are grossly limited by life-threatening graft vs host disease (GvHD). New approaches to enhance graft vs lymphoma (GvL) effects without increased GvHD are needed. Bispecific antibodies (BiAbs) are produced by linking anti-CD3 for T cell binding to an antibody specific for a tumor antigen. Anti-CD3 activated T cells (ATC) "armed" with BiAb express tumor-specific CTL function independent of further activation, proliferation, antigen presentation or costimulation. Studies here examined allo-reactivity of BiAb-armed ATC for potential application in an allogeneic setting. Data show that ATC armed with anti-CD3 x anti-CD20 BiAb specifically target and kill B cell lymphomas. However, BiAb-armed ATC are remarkably poor stimulators of, or responders to, allo-stimlulation. These results provide important evidence of a functional separation between the GvL and GvH effects of BiAb-armed ATC.

Lack of antibody affinity maturation due to poor Toll-like receptor stimulation leads to enhanced respiratory syncytial virus disease

Respiratory syncytial virus (RSV) is a leading cause of hospitalization in infants. A formalin-inactivated RSV vaccine was used to immunize children in 1966 and elicited non-protective, pathogenic antibody. Two immunized infants died and 80% were hospitalized after subsequent RSV exposure. No vaccine was licensed since.A widely accepted hypothesis attributed vaccine failure to formalin disruption of protective antigens. Instead, we show that lack of protection was not due to alterations caused by formalin, but to low antibody avidity for protective epitopes. Lack of antibody affinity maturation followed poor Toll-like receptor stimulation. This study explains why the inactivated RSV vaccine failed to protect and consequently led to severe disease, hampering vaccine development for forty-two years. Also, it suggests that inactivated RSV vaccines may be rendered safe and effective by inclusion of TLR-agonists in their formulation. In addition, it identifies affinity maturation as a critical factor for the safe immunization of infants.

Cord blood dendritic cells prevent the differentiation of naïve T-helper cells towards Th1 irrespective of their subtype

Allogeneic cord blood transplantation is associated with a less severe graft-versus-host disease (GVHD). This observation is thought to be due to immaturity of cord blood cell immune capabilities. Dendritic cells (DCs) are the most potent antigen-presenting cells of the immune system capable of initiation and regulation of immune responses. In this investigation, we hypothesized that non-manipulated cord blood dendritic cells (CBDCs) not only differ in their functional maturity from adult peripheral blood DCs (PBDCs) but also differ in their subsets and their preference in promoting Th1 or Th2 immune responses. Non-manipulated fresh DCs were isolated from cord blood (CB) and adult peripheral blood (PB) mononuclear cells as lineage marker negative cells. The differences in expression of costimulatory molecules, the proportion of myeloid and lymphoid DCs subsets, their immunostimulatory characteristics and their influence on promoting the differentiation of naïve T cells towards Th1 or Th2 cells were then investigated in these two populations. Our results showed that freshly isolated CBDCs, similar to cord blood monocyte derived DCs, were poor inducers of IFN-gamma secretion while they increased the induction of IL-4 production by T cells in comparison with PBDCs. CBDCs were also poor stimulators of allogenic T cells in mixed leukocyte reaction compared to adult peripheral blood dendritic cells. They also displayed decreased expression of HLA-DR and CD86 molecules. The ratio of lymphoid DCs (CD11c(-), CD123(+)) to myeloid DCs (CD11c(+), CD123(-)) was significantly higher in CB compared to PB. We conclude that CBDCs preferential priming of naive T cells towards Th2 population, seems to be an intrinsic property independent of their subtype. This property along with their functional immaturity should contribute to outcome of cord blood transplantation.

The immunologic properties of undifferentiated and osteogenic differentiated mouse mesenchymal stem cells and its potential application in bone regeneration

The concept of using mesenchymal stem cells (MSCs) in bone repair has progressively evolved, and the goal of cell-mediated therapy is to prolong the natural physiological abilities of healing, or substitute them, when these are lacking, failing, or progressing too slowly. The future application of MSCs in human therapies depends on the establishment of preclinical studies with other mammals, such as mouse. Surprisingly, the immunologic properties of murine MSCs remain poorly documented. In the present study, flow cytometry revealed that undifferentiated murine MSCs and osteogenic cells differentiated from MSCs (DOCs) express major histocompatibility complex (MHC) class I (H-2 b), but not class II (I-A b). After exposure to interferon-gamma (IFN- γ) for 48 h, MHC class II and costimulatory molecules (B7-1 and B7-2) on the cell surface showed evident up-regulation. Undifferentiated MSCs and DOCs proved to be poor stimulators of T cell proliferation, eliciting alloreactive lymphocyte proliferative responses as low-allogenic stimulators. Initial results show that the expression of MHC class I, MHC class II, B7-1 and B7-2 was similar on human bone morphogenetic protein 2 (BMP2)-expressing recombinant adenoviral vector (AdBMP2) transduced MSCs (30 MOI) when compared with non-transduced cells. However, AdBMP2 gene transfected MSCs elicited significant stimulatory responses. The findings will be important for studying the in vivo behaviour and the fate of MSCs after grafting in mouse pathology models in bone regeneration.

Activated B cells modified by electroporation of multiple mRNAs encoding immune stimulatory molecules are comparable to mature dendritic cells in inducing in vitro antigen‐specific T‐cell responses

Ex-vivo-activated B cells are an alternative source of antigen-presenting cells (APCs) and a potential replacement for dendritic cells (DCs) in immunotherapy. However, the ability of ex-vivo-activated B cells to function as potent APCs has been a concern, especially when compared to DCs. Our study investigated whether modification of activated B cells with immune stimulatory molecules could enhance the ability of activated B cells to stimulate T cells. We show that murine splenic B cells, activated with a combination of Toll-like receptor agonist and agonistic anti-CD40, stimulated antigen-specific CD8+ T cells more efficiently than cells activated with Toll-like receptor agonist or anti-CD40 alone, probably by down-regulation of the immune regulatory cytokine interleukin-10 (IL-10). However, the activated B cells were still poor T-cell stimulators compared to mature DCs. Therefore, we modified the activated B cells by simultaneous electroporation of multiple messenger RNAs encoding costimulatory molecules (OX40L and 4-1BBL), cytokines (IL-12p35 and IL-12p40) and antigen. We found that de novo expression or overexpression of OX40L, 4-1BBL and IL-12p70 on activated B cells synergistically enhanced proliferation as well as IL-2 and interferon-gamma production by CD8+ T cells. Furthermore, the RNA-modified activated B cells induced antigen-specific cytotoxic T lymphocyte responses as efficiently as mature DCs in vitro. Unexpectedly, modified activated B cells were inferior to mature DCs at in vivo induction of CD8+ T-cell responses. In summary, activated B cells modified to express immune stimulatory molecules are a potent alternative to DCs in immunotherapy.

Immune Properties of Human Umbilical Cord Wharton's Jelly-Derived Cells

Cells isolated from Wharton's jelly, referred to as umbilical cord matrix stromal (UCMS) cells, adhere to a tissue-culture plastic substrate, express mesenchymal stromal cell (MSC) surface markers, self-renew, and are multipotent (differentiate into bone, fat, cartilage, etc.) in vitro. These properties support the notion that UCMS cells are a member of the MSC family. Here, the immune properties of UCMS cells are characterized in vitro. The overall hypothesis is that UCMS cells possess immune properties that would be permissive to allogeneic transplantation. For example, UCMS cells will suppress of the proliferation of "stimulated" lymphocytes (immune suppression) and have reduced immunogenicity (e.g., would be poor stimulators of allogeneic lymphocyte proliferation). Hypothesis testing was as follows: first, the effect on proliferation of coculture of mitotically inactivated human UCMS cells with concanavalin-A-stimulated rat splenocytes was assessed in three different assays. Second, the effect of human UCMS cells on one-way and two-way mixed lymphocyte reaction (MLR) assays was determined. Third, the expression of human leukocyte antigen (HLA)-G was examined in human UCMS cells using reverse transcription-polymerase chain reaction, since HLA-G expression conveys immune regulatory properties at the maternal-fetal interface. Fourth, the expression of CD40, CD80, and CD86 was determined by flow cytometry. Fifth, the cytokine expression of UCMS cells was evaluated by focused gene array. The results indicate that human UCMS cells inhibit splenocyte proliferation response to concanavalin A stimulation, that they do not stimulate T-cell proliferation in a one-way MLR, and that they inhibit the proliferation of stimulated T cells in a two-way MLR. Human UCMS cells do not inhibit nonstimulated splenocyte proliferation, suggesting specificity of the response. UCMS cells express mRNA for pan-HLA-G. UCMS cells do not express the costimulatory surface antigens CD40, CD80, and CD86. UCMS cells express vascular endothelial growth factor and interleukin-6, molecules previously implicated in the immune modulation observed in MSCs. In addition, the array data indicate that UCMS cells make a cytokine and other factors that may support hematopoiesis. Together, these results support previous observations made following xenotransplantation; for example, there was no evidence of frank immune rejection of undifferentiated UCMS cells. The results suggest that human UCMS will be tolerated in allogeneic transplantation. Disclosure of potential conflicts of interest is found at the end of this article.

Expression of ICAM-1 (CD54) on normal and leukaemic B cells: implication for the mixed lymphocyte reaction.

Peripheral blood normal B lymphocytes were found to be poor stimulators in the mixed lymphocyte reaction (MLR), in contrast to normal activated B cells which were strong stimulators. This increased capacity to stimulate a strong MLR correlated with an increased expression of the ICAM-1 (CD54) molecule on the surface of these cells. Similarly, the capacity of leukaemic B cells to induce an allogenic stimulation in the MLR was limited to the ICAM-1 (CD54) positive leukaemic cells. The ability of normal activated or leukaemic B cells to induce an MLR was blocked by antibodies directed against ICAM-1.

Characterization of immune inducer and suppressor macrophages from the normal human lung

Monoclonal antibodies (MoAbs) that are able to discriminate between dendritic cells (MoAb RFD1+) and mature macrophages (MoAb RFD7+) in normal tissues were used in combination with density separation techniques to isolate relatively homogeneous subpopulations of macrophages from human bronchoalveolar lavage (BAL). A characterization of surface antigen expression, and functional capacity was then carried out on each isolated alveolar macrophage (AM) subset. One population with the phenotype RFD1+RFD7- obtained from the non-adherent cell pool showed the characteristics of antigen-presenting cells having absent or poor expression of Fc and C3b receptors, a low content of lysozomal hydrolase and poor phagocytic capacity. This population strongly stimulated T lymphocytes in allogeneic mixed lymphocyte reactions (MLR). A second AM population, isolated by adherence and density centrifugation expressed the phenotype RFD1+RFD7+. These cells showed the same phenotypic characteristics of mature macrophages with strong expression of C3b and Fc receptors, and marked phagocytic capacity. Such AM were very poor stimulators of allogeneic MLR. Under certain circumstances the RFD1+RFD7+ cells were shown to actively repress the stimulatory capacity of the RFD1+RFD7- subpopulation. These results suggest that variations within the functional capacity of AM subsets may be capable of influencing the strength of acquired T cell immune responses of the lung.

Conducting polymers for neural interfaces: Challenges in developing an effective long-term implant

Metal electrode materials used in active implantable devices are often associated with poor long-term stimulation and recording performance. Modification of these materials with conducting polymer coatings has been suggested as an approach for improving the neural tissue-electrode interface and increasing the effective lifetime of these implants. Neural interfaces ideally have intimate contact between the excitable tissue and the electrode to maintain signal quality and activation of neural cells. The outcomes of current research into conducting polymers as coatings has potential to enhance this tissue-material contact by increasing the electrode surface area and roughness as well as allowing delivery of bioactive signals to neural cells. However, challenges facing conducting polymers include poor electroactive stability and mechanical properties as well as control of the mobility, concentration and presentation of bioactive molecules. The impact of biological inclusions on polymer properties and their ongoing performance in neural prosthetics requires a greater understanding with future research aimed at controlling and optimising film characteristics for long-term performance. Optimising the electrode interface will require a trade-off between desired electrical, mechanical, chemical and biological properties.

Niflumic acid renders dendritic cells tolerogenic and up-regulates inhibitory molecules ILT3 and ILT4

Niflumic acid is a member of non-steroidal anti-inflammatory agents, from which aspirin was recently shown to inhibit maturation of human-monocyte derived dendritic cells (DCs). DCs are crucial regulators of the immune response, capable of inducing immunity as well as tolerance. In our in vitro study we showed a tolerogenic effect of NFA on phenotype and function of LPS-matured monocyte-derived DCs. Different drug concentrations dose-dependently down-regulated the expression of co-stimulatory molecules, particularly CD80 and lowered the expression of dendritic cell marker CD1a. Opposingly, the expressions of two inhibitory surface molecules, associated with tolerogenic DCs, immunoglobulin-like transcripts (ILT)3 and ILT4 were induced in treated DCs. The levels of TNFα production by NFA-treated DCs did not change significantly compared to controls, whereas the IL-12p70 and IL-10 production was completely abrogated at higher drug concentrations. However, at lower drug concentrations, the production of IL-12p70 was increased. There were no significant differences in the uptake of FITC labeled dextran by treated DCs compared to untreated cells. In allogeneic cultures with whole CD4 + T cells, dendritic cells differentiated in the presence of NFA appeared poor stimulators of CD4 + T-cell proliferation, even compared to immature DCs (iDCs). These results indicate the immunosuppressive properties of NFA, which may be therapeutically useful in controlling chronic immune and/or inflammatory diseases, by modulating DC characteristics towards tolerogenic DCs.