Sitagliptin Induces Tolerogenic Human Dendritic Cells.

Sitagliptin, an anti-diabetic drug, is a dipeptidyl peptidase (DPP)-4/CD26 inhibitor with additional anti-inflammatory and immunomodulatory properties. In this study, we investigated for the first time the effect of sitagliptin on the differentiation and functions of human dendritic cells generated from monocytes (MoDCs) for 4 days using the standard GM-CSF/IL-4 procedure. LPS/IFN-γ treatment for an additional 24 h was used for maturation induction of MoDCs. Sitagliptin was added at the highest non-cytotoxic concentration (500 µg/mL) either at the beginning (sita 0d protocol) or after MoDC differentiation (sita 4d protocol). Sitagliptin impaired differentiation and maturation of MoDCs as judged with the lower expression of CD40, CD83, CD86, NLRP3, and HLA-DR, retention of CD14 expression, and inhibited production of IL-ß, IL-12p70, IL-23, and IL-27. In contrast, the expression of CD26, tolerogenic DC markers (ILT4 and IDO1), and production of immunoregulatory cytokines (IL-10 and TGF-ß) were increased. Generally, the sita 0d protocol was more efficient. Sitagliptin-treated MoDCs were poorer allostimulators of T-cells in MoDC/T-cell co-culture and inhibited Th1 and Th17 but augmented Th2 and Treg responses. Tolerogenic properties of sitagliptin-treated MoDCs were additionally confirmed by an increased frequency of CD4+CD25+CD127- FoxP3+ Tregs and Tr1 cells (CD4+IL-10+FoxP3-) in MoDC/T-cell co-culture. The differentiation of IL-10+ and TGF-ß+ Tregs depended on the sitagliptin protocol used. A Western blot analysis showed that sitagliptin inhibited p65 expression of NF-kB and p38MAPK during the maturation of MoDCs. In conclusion, sitagliptin induces differentiation of tolerogenic DCs, and the effect is important when considering sitagliptin for treating autoimmune diseases and allotransplant rejection.

Efficacy of nebulized hypertonic saline versus normal saline in the treatment of acute bronchiolitis in inpatient infants.

Aim Compare the efficacy of nebulized hypertonic saline and normal saline in the treatment of infants hospitalized for bronchiolitis. Methods This retrospective study was conducted at the Department of Pulmonology, Paediatric Clinic, Clinical Centre University of Sarajevo, covering the period from January 2015 to December 2019 and comprising 380 children aged between 1 and 12 months having bronchiolitis. One group received nebulized hypertonic saline (NHS, 3% NaCl)), and another group received nebulized normal saline (NNS, 0.9% NaCl). The control group did not receive any of these treatment options. Results There was no statistically significant difference between the treatment groups regarding length of hospital stay (LOS) and Clinical Severity Score (CSS) at admission and discharge as well as in oxygen therapy duration and antibiotic use, the duration of symptoms before hospital admission, frequency of nasal discharge, elevated temperature, dyspnoea, cough and dehydration. Conclusion The results of this study are consistent with several recent studies or meta-analyses and support the evidence against the use of NHS in hospitalized infants with mild or moderate bronchiolitis.

Dysfunctions of Neutrophils in the Peripheral Blood of Children with Cystic Fibrosis.

Dysfunction of neutrophils in patients with cystic fibrosis (CF) is best characterized in bronchoalveolar lavage (BAL), whereas peripheral blood neutrophils are less examined, and the results are contradictory, especially in younger populations. Therefore, this work aimed to study functional and phenotypic changes in circulating neutrophils in children with CF. The study included 19 CF children (5-17 years) and 14 corresponding age-matched healthy children. Isolated neutrophils were cultured either alone or with different stimuli. Several functions were studied: apoptosis, NET-osis, phagocytosis, and production of reactive oxygen species (ROS), neutrophil elastase (NE), and 11 cytokines. In addition, the expression of 20 molecules involved in different functions of neutrophils was evaluated by using flow cytometry. CF neutrophils showed reduced apoptosis and lower production of NE and IL-18 compared to the healthy controls, whereas IL-8 was augmented. All of these functions were further potentiated after neutrophil stimulation, which included higher ROS production and the up-regulation of CD11b and IL-10 expression. NET-osis was higher only when neutrophils from moderate-severe CF were treated with Pseudomonas aeruginosa, and the process correlated with forced expiratory volume in the first second (FEV1). Phagocytosis was not significantly changed. In conclusion, circulating neutrophils from children with CF showed fewer impaired changes in phenotype than in function. Functional abnormalities, which were already present at the baseline levels in neutrophils, depended on the type of stimuli that mimicked different activation states of these cells at the site of infection.

Immunomodulatory Activity of Punicalagin, Punicalin, and Ellagic Acid Differs from the Effect of Pomegranate Peel Extract.

BACKGROUND: Our recent study has shown that pomegranate peel extract (PEx) showed significant immunomodulatory activity, which might be caused by ellagitannins. The aim of this work was to test the hypothesis that ellagitannin components act synergistically in the modulation of cytokine production. METHODS: Human peripheral blood mononuclear cells (PBMCs) from healthy donors were stimulated with phytohemagglutinin and treated with different concentrations of PEx or punicalagin (PG), punicalin (PN), and ellagic acid (EA), alone or with their combinations. Cytotoxicity, cell proliferation, and cytokine production were determined. RESULTS: Non-cytotoxic concentrations of all compounds significantly inhibited cell proliferation. IC50 values (µg/mL) were: EA (7.56), PG (38.52), PEx (49.05), and PN (69.95). PEx and all ellagitannins inhibited the levels of TNF-α, IL-6, and IL-8, dose-dependently, and their combinations acted synergistically. PEx and all ellagitannins inhibited Th1 and Th17 responses, whereas the lower concentrations of PEx stimulated the production of IL-10, a Treg cytokine, as did lower concentrations of EA. However, neither component of ellagitannins increased Th2 response, as was observed with PEx. CONCLUSIONS: The combination of PG, PN, and EA potentiated the anti-inflammatory response without any significant synergistic down-modulatory effect on T-cell cytokines. The increased production of IL-10 observed with PEx could be attributable to EA, but the examined ellagitannins are not associated with the stimulatory effect of PEx on Th2 response.

MMP-9/BDNF ratio predicts more severe COVID-19 outcomes.

COVID-19 clinically manifests from asymptomatic to the critical range. Immune response provokes the pro-inflammatory interactions, which lead to the cytokines, reactive oxygen/nitrogen species, peptidases, and arachidonic acid metabolites enlargement and activation of coagulation components. Matrix metalloproteinases (MMPs) contribute to tissue destruction in the development of COVID-19. Due to the endothelial, systemic course of the disease, VEGF A participates actively in COVID-19 development, while neurotrophic and metabolic effects of BDNF recommends for the prediction of complications in COVID-19 patients. Searching for a marker that would improve and simplify the ranking in COVID-19, the study intended to evaluate the relationship of MMP-9 with VEGF A, BDNF, and MMP-8 with the COVID-19 severity. Upon admission to the hospital and before the therapy administration, 77 patients were classified into a mild, moderate, severe, or critical group. Due to the inflammatory stage in COVID-19, a comparison between groups showed related differences in leukocytes, neutrophils, lymphocytes, and platelets counts as anticipated. Only in seriously ill patients, there is a significant increase in the serum concentration of MMP-9, MMP-8, and VEGF A, while BDNF values did not show significant variations between groups. However, all those parameters positively correlated with each other. The ratio of MMP-9/BDNF markedly decreased in the severe and critically patients compared to the mild group. Testing the capability of this ratio to predict the COVID-19 stage by ROC curves, we found the MMP-9/BDNF could be a suitable marker for differentiating stages I/II (AUC 0.7597), stage I/III (AUC 0.9011), and stage I/IV (AUC 0.7727). Presented data describe for the first time the high-level systemic MMP-9/BDNF ratio in patients with COVID-19. This parameter could contribute to a more precise determination of the phase of the disease.

Phosphonate-Modified Cellulose Nanocrystals Potentiate the Th1 Polarising Capacity of Monocyte-Derived Dendritic Cells via GABA-B Receptor.

Purpose: Phosphonates, like 3-AminoPropylphosphonic Acid (ApA), possess a great potential for the therapy of bone tumours, and their delivery via cellulose nanocrystals (CNCs) seems a promising approach for their increased efficacy in target tissues. However, the immunological effects of CNC-phosphonates have not been investigated thoroughly. The main aim was to examine how the modification of CNCs with phosphonate affects their immunomodulatory properties in human cells. Methods: Wood-based native (n) CNCs were modified via oxidation (ox-CNCs) and subsequent conjugation with ApA (ApA-CNCs). CNCs were characterised by atomic force microscopy (AFM) and nanoindentation. Cytotoxicity and immunomodulatory potential of CNCs were investigated in cultures of human peripheral blood mononuclear cells (PBMCs) and monocyte-derived dendritic cells (MoDCs)/T cells co-cultures by monitoring phenotype, cytokines production, allostimulatory and Th/Treg polarisation capacity. Results: AFM showed an increase in CNCs' thickens, elasticity modulus and hardness during the modification with ApA. When applied at non-toxic doses, nCNCs showed a tolerogenic potential upon internalisation by MoDCs, as judged by their increased capacity to up-regulate tolerogenic markers and induce regulatory T cells (Treg), especially when present during the differentiation of MoDCs. In contrast, ox- and ApA-CNCs induced oxidative stress and autophagy in MoDCs, which correlated with their stimulatory effect on the maturation of MoDCs, but also inhibition of MoDCs differentiation. ApA-CNC-treated MoDCs displayed the highest allostimulatory and Th1/CTL polarising activity in co-cultures with T cells. These effects of ApA-CNCs were mediated via GABA-B receptor-induced lowering of cAMP levels in MoDCs, and they could be blocked by GABA-B receptor inhibitor. Moreover, the Th1 polarising and allostimulatory capacity of MoDCs differentiated with ApA-CNC were largely preserved upon the maturation of MoDCs, whereas nCNC- and ox-CNC-differentiated MoDCs displayed an increased tolerogenic potential. Conclusion: The delivery of ApA via CNCs induces potent DC-mediated Th1 polarisation, which could be beneficial in their potential application in tumour therapy.

Ex vivo study of IL-6 expression and function in immune cell subsets from human periapical lesions.

AIM: Even though IL-6 is a key inflammatory cytokine in periapical lesions (PLs), its function in stable periapical disease is unknown. Therefore, the aim of this study was to investigate the following: first, the ex vivo production of IL-6 by clinically different PLs; next, subsets of immune cells expressing IL-6 in PLs according to their inflammatory status and finally, modulatory effect of IL-6 on T-cell cytokine production in cell cultures. METHODOLOGY: Inflammatory cells were isolated from a total of 95 human PLs. Detection of IL-6+ cells within the myeloid and lymphoid populations was performed by multicolour flow cytometry. ELISA and FlowCytomix Microbeads Assay were used to measure cytokine levels in culture supernatants. To study the role of IL-6 in PLs, mononuclear cells (MNC) from symptomatic (Sy) or asymptomatic (Asy) PLs were treated with IL-6 or Tocilizumab, an IL-6R blocking antibody. The differences between groups were tested by unpaired t-test, Mann-Whitney or Friedman tests. RESULTS: The levels of IL-6 in PL MNC culture supernatants were significantly higher compared with total PL cells and PL granulocytes (p < .001). MNC from Sy PLs produced significantly higher levels of IL-6 than MNC from Asy PLs (p < .001). Flow cytometry analysis showed that NKT cells, CD8+ T cells and M2 macrophages (MØ), were dominant IL-6+ cells, in contrast to CD4+ T cells. However, CD8+ and CD4+ T cells contributed the most to IL-6 production. IL-6hi producing MNC cultures had higher levels of Th1 (IFN-γ), Th17 (IL-17A), Tfh (IL-21) and RANKL, whereas Th2 (IL-4) and Tregs cytokines (IL-10, TGF-ß) were lower compared with IL-6low -producing cultures. Exogenous IL-6 stimulated 17A, IL-21 and RANKL, independently of PL activation status, but decreased IFN-γ, IL-4 and IL-33 levels in IL-6hi -producing cultures. Tocilizumab increased IL-10 and TGF-ß in IL-6low -producing cultures. All differences were p < .05. CONCLUSIONS: Most immune cells from Sy PLs expressed higher levels of IL-6 compared with Asy PLs, which correlated with IL-6 production in culture. Analysis of cytokines suggested a dominant pro-inflammatory T-cell response and osteodestructive function of IL-6 in PLs judging by Th17/Tfh cell activation, Tregs inhibition and increased RANKL/OPG ratio. Excessive IL-6 production decreased Th1/Th2 responses.

Fecal microbiota composition associates with the capacity of human peripheral blood monocytes to differentiate into immunogenic dendritic cells in vitro.

Although promising for active immunization in cancer patients, dendritic cells (DCs) vaccines generated in vitro display high inter-individual variability in their immunogenicity, which mostly limits their therapeutic efficacy. Gut microbiota composition is a key emerging factor affecting individuals' immune responses, but it is unknown how it affects the variability of donors' precursor cells to differentiate into immunogenic DCs in vitro. By analyzing gut microbiota composition in 14 healthy donors, along with the phenotype and cytokines production by monocyte-derived DCs, we found significant correlations between immunogenic properties of DC and microbiota composition. Namely, donors who had higher α-diversity of gut microbiota and higher abundance of short-chain fatty acid (SCFAs) and SCFA-producing bacteria in feces, displayed lower expression of CD1a on immature (im)DC and higher expression of ILT-3, costimulatory molecules (CD86, CD40) proinflammatory cytokines (TNF-α, IL-6, IL-8) and IL-12p70/IL-10 ratio, all of which correlated with their lower maturation potential and immunogenicity upon stimulation with LPS/IFNγ, a well-known Th1 polarizing cocktail. In contrast, imDCs generated from donors with lower α-diversity and higher abundance of Bifidobacterium and Collinsella in feces displayed higher CD1a expression and higher potential to up-regulate CD86 and CD40, increase TNF-α, IL-6, IL-8 production, and IL-12p70/IL-10 ratio upon stimulation. These results emphasize the important role of gut microbiota on the capacity of donor precursor cells to differentiate into immunogenic DCs suitable for cancer therapy, which could be harnessed for improving the actual and future DC-based cancer therapies.

Functionalization-dependent effects of cellulose nanofibrils on tolerogenic mechanisms of human dendritic cells.

BACKGROUND: Cellulose nanofibrils (CNF) are attractive nanomaterials for various biomedical applications due to their excellent biocompatibility and biomimetic properties. However, their immunoregulatory properties are insufficiently investigated, especially in relation to their functionalization, which could cause problems during their clinical application. METHODS: Using a model of human dendritic cells (DC), which have a central role in the regulation of immune response, we investigated how differentially functionalized CNF, ie, native (n) CNF, 2,2,6,6-tetramethylpiperidine 1-oxyl radical-oxidized (c) CNF, and 3-aminopropylphosphoric acid-functionalized (APAc) CNF, affect DC properties, their viability, morphology, differentiation and maturation potential, and the capacity to regulate T cell-mediated immune response. RESULTS: Nontoxic doses of APAcCNF displayed the strongest inhibitory effects on DC differentiation, maturation, and T helper (Th) 1 and Th17 polarization capacity, followed by cCNF and nCNF, respectively. These results correlated with a specific pattern of regulatory cytokines production by APAcCNF-DC and their increased capacity to induce suppressive CD8+CD25+IL-10+ regulatory T cells in immunoglobulin-like transcript (ILT)-3- and ILT-4- dependent manner. In contrast, nCNF-DC induced predominantly suppressive CD4+CD25hiFoxP3hi regulatory T cells in indolamine 2,3-dioxygenase-1-dependent manner. Different tolerogenic properties of CNF correlated with their size and APA functionalization, as well as with different expression of CD209 and actin bundles at the place of contact with CNF. CONCLUSION: The capacity to induce different types of DC-mediated tolerogenic immune responses by functionalized CNF opens new perspectives for their application as well-tolerated nanomaterials in tissue engineering and novel platforms for the therapy of inflammatory T cell-mediated pathologies.

Nanoaggregates of iron poly-oxo-clusters obtained by laser ablation in aqueous solution of phosphonates.

Laser ablation in liquid (LAL) emerged as a versatile technique for the synthesis of nanoparticles with various structures and compositions, although the control over products remains challenging in most cases. For instance, it is still difficult to drive the size of metal oxide crystalline domains down to the level of few atom clusters with LAL. Here we demonstrate that laser ablation of a bulk iron target in aqueous solution of phosphonates gives phosphonate-grafted iron oxo-clusters polymerized into nanoaggregates with Fe:ligand ratio of 2:1, instead of the usual nanocrystalline iron oxides. We attribute this result to the strong ability of phosphonate groups to bind iron oxide clusters and prevent their further growth into crystalline iron oxide. These laser generated poly-oxo-clusters are biocompatible and trackable by magnetic resonance imaging, providing interesting features for use in biological environments, such as nano-vehicles for iron administration. Besides, this method is promising for the generation of atom-scale metal-oxide clusters, which are ubiquitary in chemistry and of interest in biochemistry, catalysis, molecular magnetism and materials science.

Eosinophil Cationic Protein in Patients with Differentiated Thyroid Cancer Treated with Radioactive Iodine 131.

Published data indicate the involvement of eosinophil granulocytes and eosinophil cationic protein (ECP) in tumor defense. The aim of this study was to analyze serum ECP concentrations in patients with differentiated thyroid cancer (DTC) before, 3 days and 7 days after radioactive iodine (131-I) therapy. Association of ECP concentrations with histological type of tumor, stage of disease and/or levels of selected T-helper 2 (Th2) cytokines was examined. The study population included 17 DTC patients and 10 control subjects. ECP was measured by fluoroimmunoassay (FIA). Th2 (cytokines interleukin 4 (IL-4), interleukin 5 (IL-5), and interleukin 13 (IL-13)) were determined by enzyme-linked immunosorbent assays (ELISA). We found that ECP values in DTC patients before radioactive iodine therapy were approximately two-fold higher than in the controls, but the difference was statistically significant only if the patients with DTC and associated Hashimoto thyroiditis (HT) were included. There was no correlation between the serum concentrations of IL-5 and ECP. Radioactive iodine therapy led to a decrease in serum ECP level which did not follow the decline in serum protein levels. Additional studies are needed to determine the significance of these findings.

Graphene quantum dots suppress proinflammatory T cell responses via autophagy-dependent induction of tolerogenic dendritic cells.

Graphene quantum dots (GQD) are atom-thick nanodimensional carbon sheets with excellent physico-chemical and biological properties, making them attractive for application in theranostics. However, their immunoregulatory properties are insufficiently investigated, especially in human primary immune cells. We found that non-toxic doses of GQD inhibit the production of proinflammatory and T helper (Th)1 cytokines, and augment the production of anti-inflammatory and Th2 cytokines by human peripheral blood mononuclear cells. While unable to affect T cells directly, GQD impaired the differentiation and functions of monocyte-derived dendritic cells (DC), lowering their capacity to stimulate T cell proliferation, development of Th1 and Th17 cells, and T-cell mediated cytotoxicity. Additionally, GQD-treated DC potentiated Th2 polarization, and induced suppressive CD4+CD25highFoxp3+ regulatory T cells. After internalization in a dynamin-independent, cholesterol-dependent manner, GQD lowered the production of reactive oxygen species and nuclear translocation of NF-κB in DC. The activity of mammalian target of rapamycin (mTOR) was reduced by GQD, which correlated with the increase in transcription of autophagy genes and autophagic flux in DC. Genetic suppression of autophagy impaired the pro-tolerogenic effects of GQD on DC. Our results suggest that GQD-triggered autophagy promotes tolerogenic functions in monocyte-derived DC, which could be beneficial in inflammatory T-cell mediated pathologies, but also harmful in GQD-based anti-cancer therapy.

Depurinized milk downregulates rat thymus MyD88/Akt/p38 function, NF-κB-mediated inflammation, caspase-1 activity but not the endonuclease pathway: in vitro/in vivo study.

The aim of this study was the evaluation of 15 days dietary regimen of depurinized (DP) milk (obtained using our patented technological procedures) or 1.5% fat UHT milk instead of standard chow diet, on rat thymus and bone marrow MyD88/Akt/p38, NF-κB, caspase-1 and endonuclease pathways, in relation to peripheral blood cell composition. To determine whether the reduced mass of the thymus is a consequence of the direct effect of DP/UHT milk on apoptosis of thymocytes, in vitro Annexin-V-FITC/PI assay was performed. Significant decreases in the thymus wet weight, thymocyte MyD88, Akt-1/phospho-Akt-1 kinase, p38/phospho-p38, NF-κB, caspase-1 activity and CD4+/CD8+ antigen expression were obtained, especially in the DP milk group. The activity of thymocyte alkaline and acid DNase increased in the DP but not in the UHT milk group. The level of IL-6 significantly decreased in DP milk treated group, while the level of total TGF-ß and IL-6 increased in UHT milk group. Significant differences in hematological parameters were obtained in commercial milk fed group. Observed results about prevention of experimental diabetes in DP pretreated groups may suggest that purine compounds, uric acid and other volatile toxic compounds of commercial milk may suppress oral tolerance, probably via IL-6 and TGF-ß cytokine effects.

Native cellulose nanofibrills induce immune tolerance in vitro by acting on dendritic cells.

Cellulose nanofibrills (CNFs) are attractive biocompatible, natural nanomaterials for wide biomedical applications. However, the immunological mechanisms of CNFs have been poorly investigated. Considering that dendritic cells (DCs) are the key immune regulatory cells in response to nanomaterials, our aim was to investigate the immunological mechanisms of CNFs in a model of DC-mediated immune response. We found that non-toxic concentrations of CNFs impaired the differentiation, and subsequent maturation of human monocyte-derived (mo)-DCs. In a co-culture with CD4(+)T cells, CNF-treated mo-DCs possessed a weaker allostimulatory and T helper (Th)1 and Th17 polarizing capacity, but a stronger capacity to induce Th2 cells and CD4(+)CD25(hi)FoxP3(hi) regulatory T cells. This correlated with an increased immunoglobulin-like transcript-4 and indolamine dioxygenase-1 expression by CNF-treated mo-DCs, following the partial internalization of CNFs and the accumulation of CD209 and actin bundles at the place of contacts with CNFs. Cumulatively, we showed that CNFs are able to induce an active immune tolerance by inducing tolerogenic DCs, which could be beneficial for the application of CNFs in wound healing and chronic inflammation therapies.

Transforming Growth Factor Beta 1 (TGF-ß1) in Thyroid Cancer Patients: a View from the Peripheral Blood.

Transforming growth factor beta (TGF-ß) plays an important role in many pathophysiological conditions, including cancer. The level of TGF-ß in patients with differentiated thyroid cancer (DTC) has not been examined so far. The aim of this study was to measure TGF-ß concentration in serum samples and in PHA-stimulated whole blood culture in vitro and to analyze possible associations of TGF-ß1 levels with leukocyte, lymphocyte and platelets counts, the histological type of thyroid cancer, and stage of disease. TGF-ß1 was measured in 22 DTC patients and 20 healthy controls using the duoSet ELISA Development kit for human TGF-ß1. The concentration of TGF-ß1 in serum samples from both groups correlated positively with the platelet counts. There was no statistically significant difference in the serum concentrations of TGF-ß1 between DTC patients and control subjects, but PHA stimulated whole blood cultures of DTC patients produced less TGF-ß1 than those from controls. Additional studies are needed to determine the significance of these in vitro findings.

Cytokine production in patients with papillary thyroid cancer and associated autoimmune Hashimoto thyroiditis.

Hashimoto thyroiditis (HT) is the most frequent thyroid autoimmune disease, while papillary thyroid cancer (PTC) is one of the most common endocrine malignancies. A few patients with HT also develop PTC. The aim of this study was to analyze cytokine profiles in patients with PTC accompanied with autoimmune HT in comparison with those in patients with PTC alone or HT alone and healthy subjects. Cytokine levels were determined in supernatants obtained from phytohemagglutinin (PHA)-stimulated whole blood cultures in vitro. The concentrations of selected cytokines: Th1-interferon gamma (IFN-γ); Th2-interleukin 4 (IL-4), interleukin 5 (IL-5), interleukin 6 (IL-6), interleukin 10 (IL-10) and interleukin 13 (IL-13); Th9-interleukin 9 (IL-9); and Th17-interleukin 17 (IL-17A) were measured using multiplex cytokine detection systems for human Th1/Th2/Th9/Th17/Th22. We found that PTC patients with HT produced significantly higher concentrations of IL-4, IL-6, IL-9, IL-13 and IFN-γ than PTC patients without HT. In conclusion, autoimmune HT affects the cytokine profile of patients with PTC by stimulating secretion of Th1/Th2/Th9 types of cytokines. Th1/Th2 cytokine ratios in PTC patients with associated autoimmune HT indicate a marked shift toward Th2 immunity.

Tumor necrosis factor-α promotes survival and phenotypic maturation of poly(I:C)-treated dendritic cells but impairs their Th1 and Th17 polarizing capability.

BACKGROUND AIMS: Toll-like receptor (TLR)-3 synthetic agonist polyinosinic-polycytidylic acid (poly(I:C)) is a promising agent for dendritic cell (DC)-based anti-tumor vaccines because of its ability to induce a strong maturation of DCs, but such an effect is followed by stimulation of DC apoptosis. Tumor necrosis factor (TNF)-α may promote the survival of poly(I:C)-stimulated DCs, but it is not known in detail how this combination affects the maturation and polarization capacity of monocyte-derived (Mo)DCs. METHODS: Immature MoDCs, generated from human monocytes, were treated with different concentrations of poly(I:C) combined with TNF-α, and the effect on survival, phenotype, production of cytokines, allostimulatory and Th polarization capacity was assessed after 24 and 48 h. RESULTS: We showed that TNF-α inhibited the dose-dependent pro-apoptotic effect of poly(I:C). However, TNF-α also decreased poly(I:C)-induced production of interleukin (IL)-12 and IL-23 by MoDCs, which correlated with their diminished capacity to stimulate cellular proliferation, interferon-γ and IL-17 production by allogeneic CD4(+)T cells in co-culture. Such an effect was more pronounced after 24 h and could not be restored by CD40 ligation. In the presence of CD40L, TNF-α even stimulated IL-10 production and immunoglobulin-like transcript 3 expression by poly(I:C)-matured DCs, which correlated with their increased capacity to induce IL-10 production by CD4(+)T cells. CONCLUSION: Even though TNF-α could promote the survival of poly(I:C)-matured MoDCs, it also suppresses key anti-tumor functions of these cells, which could have important implications when considering this, already suggested, protocol for the DC-based anti-tumor therapy.