Two-step maturation of immature DCs with proinflammatory cytokine cocktail and poly(I:C) enhances migratory and T cell stimulatory capacity

Saccharomyces cerevisiae oral immunization in mice using multi-antigen of the African swine fever virus elicits a robust immune response

African swine fever virus (ASFV) is one of the most complex viruses. ASFV is a serious threat to the global swine industry because no commercial vaccines against this virus are currently available except in Vietnam. Moreover, ASFV is highly stable in the environment and can survive in water, feed, and aerosols for a long time. ASFV is transmitted through the digestive and respiratory tract. Mucosal immunity is the first line of defense against ASFV. Saccharomyces cerevisiae (SC), which has been certified by the U.S. Food and Drug Administration and has a generally recognized as safe status in the food industry, was used for oral immunization in this study. ASFV antigens were effectively expressed in recombinant SC strains with high DNA copy numbers and stable growth though surface display technology and chromosome engineering (δ-integration). The recombinant SC strains containing eight ASFV antigens-KP177R, E183L, E199L, CP204L, E248R, EP402R, B602L, and B646L- induced strong humoral and mucosal immune responses in mice. There was no antigenic competition, and these antigens induced Th1 and Th2 cellular immune responses. Therefore, the oral immunization strategy using recombinant SC strains containing multiple ASFV antigens demonstrate potential for future testing in swine, including challenge studies to evaluate its efficacy as a vaccine against ASFV.

Human dendritic cell targeting peptide can be targeted to porcine dendritic cells to improve antigen capture efficiency to stimulate stronger immune response

Dendritic cells (DCs) play a key role in the natural recognition of pathogens and subsequent activation of adaptive immune responses due to their potent antigen-presenting ability. Dendritic cell-targeting peptide (DCpep) is strongly targeted to DCs, which often express antigens, to enhance the efficacy of vaccines. Our previous study showed that recombinant Lactobacillus expressing human DCpep could significantly induce stronger immune responses than recombinant Lactobacillus without DCpep, but the mechanism remains unclear. In this study, the mechanism by which DCpep enhances the immune response against recombinant Lactobacillus was explored. Fluorescence-labeled human DCpep was synthesized to evaluate the binding ability of human DCpep to porcine monocyte-derived dendritic cells (Mo-DCs) and DCs of the small intestine. The effects of Mo-DC function induced by recombinant Lactobacillus expressing human DCpep fused with the porcine epidemic diarrhea virus (PEDV) core neutralizing epitope (COE) antigen were also investigated. The results showed that human DCpep bind to porcine DCs, but not to porcine small intestinal epithelial cells. Human DCpep can also improve the capture efficiency of recombinant Lactobacillus by Mo-DCs, promote the maturation of dendritic cells, secrete more cytokines, and enhance the ability of porcine DCs to activate T-cell proliferation. Taken together, these results promote advanced understanding of the mechanism by which DCpep enhances immune responses. We found that some DCpeps are conserved between humans and pigs, which provides a theoretical basis for the development of a DC-targeted vaccine.

Mifepristone regulates Tregs function mediated by dendritic cells through suppressing the expression of TGF-β

BACKGROUND

Previous studies have demonstrated that mifepristone in the daily low-dose affects the function of endometrium. These researches also implied an alteration of endometrium immune balance, which might be involved in regulating endometrial function. However, the detailed mechanisms remain to be further explored.

METHODS

In this study, the expressions of CD80, CD86, and ICAM-1 in dendritic cells (DCs), which were stimulated with different concentrations of mifepristone (20, 65, and 200 nM), were detected by FACS. After that, we further evaluated the expression of Forkhead box P3 (FOXP3) and IL-10 in Tregs, which co-cultured with mifepristone treated DCs. In mechanism, we compared the indoleamine 2,3-dioxygenase (IDO) and TGF-β expression with enzyme-linked immunosorbent assay (ELISA).

RESULTS

The results indicated that mifepristone promoted the expressions of CD80, CD86, and ICAM-1 in a dosage dependent manner. Reversely, FOXP3 and IL-10 expression levels in Tregs co-cultured with mifepristone-treated DCs were significantly decreased compared with those co-cultured with nontreated DC. Furthermore, a significant reduce in IDO and TGF-β expression was observed in DCs treated with mifepristone. By using the IDO inhibitor (1-methyl tryptophan, 1-MT) or TGF-b supplement, we confirmed that TGF-β, but not IDO could rescue the downregulation of FOXP3 and IL-10 in Tregs co-cultured with mifepristone treated DCs. All of these results suggest that mifepristone may regulate DC function by decreasing TGF-β expression, which further results in the downregulations of FOXP3 and IL-10 in Tregs.

CONCLUSION

Therefore, our research provides a theoretical basis for a potentially clinical application of mifepristone as a novel contraceptive.

Genetically engineered probiotic Saccharomyces cerevisiae strains mature human dendritic cells and stimulate Gag-specific memory CD8+ T cells ex vivo

Recombinant Saccharomyces cerevisiae strains expressing HIV antigens have shown promising pre-clinical results. Probiotic S. cerevisiae strains naturally induce gut immunity; thus, genetically engineered probiotic strains could be used to stimulate immune responses against HIV in the mucosa. Probiotic strains have a higher rate of heterologous protein production, meaning higher antigen's epitope expression levels per yeast cell. We expressed HIV-1 Gag protein in the probiotic yeasts' surface, which was eagerly phagocytosed by and induced type 1 polarization of human monocyte-derived dendritic cells (DCs) from healthy donors in vitro. We further matured DCs derived from HIV-1⁺ donors with transformed yeasts and incubated them with autologous T cells. Only DCs matured with Gag-expressing probiotic strains were able to efficiently present antigen to CD8⁺ T cells and induced their clonal expansion. Our results show that genetically engineered probiotic S. cerevisiae strains are a promising vaccination strategy against HIV.

Addition of CpG ODN and Poly (I:C) to a standard maturation cocktail generates monocyte-derived dendritic cells and induces a potent Th1 polarization with migratory capacity

Monocyte-derived dendritic cells (DCs) are used as immunoadjuvant cells in cancer vaccines and have made great progress. However, an optimal DCs subset is vital for this treatment effect, the current 'gold standard' cytokine cocktail DCs have a shortcoming in their cytokines secretion, especially IL-12p70, mainly because of the existence of PGE2. Therefore, it is necessary to find an appropriate DCs-based immunotherapeutic protocol. In this study, we compared a novel 'improved' maturation cytokine cocktail with the current 'gold standard' maturation cytokine cocktail used for generating standard DCs. The 'improved' maturation cytokine cocktail DCs showed a higher levels surface markers expression (CD80, CD83, CD86 and HLA-DR), the chemokine receptors CXCR4 and CCR7 and chemokine CCL19, CCL21 and CXCL21, whereas CCR5 expression was reduced. Most importantly, in contrast to 'gold standard' DCs, which secrete little IL-12p70 and as a result induce mainly Th2 immunity, 'improved' cytokine cocktail DCs secreted higher levels IL-12p70 and also secreted similar concentration IL-10. To removal of PGE2 from the 'improved' DCs did increase the IL-12p70 production. In conclusion, we here present the 'improved' DCs, as an optimal maturation cocktail protocol, can induce high migratory potential, generate immunostimulatory DCs, produce higher levels IL-12p70 with superior capacity to induce Th1 immunity, when compared with the 'gold standard' DCs.

Flt3 ligand induces monocyte proliferation and enhances the function of monocyte-derived dendritic cells in vitro

Flt3 ligand (FL), a potent hematopoietic cytokine, plays an important role in development and activation of dendritic cells (DCs) and natural killer cells (NK). Although some post-receptor signaling events of FL have been characterized, the role of FL on Flt3 expressing human peripheral blood monocyte is unclear. In the current study, we examined the role of FL on cell survival and growth of peripheral blood monocytes and function of monocyte-derived DCs. FL promoted monocyte proliferation in a dose-dependent manner and prevented spontaneous apoptosis. FL induced ERK phosphorylation and a specific ERK inhibitor completely abrogated FL-mediated cellular growth, while p38 MAPK, JNK, and AKT were relatively unaffected. Addition of FL to GM-CSF and IL-4 during DCs generation from monocytes increased the yield of DCs through induction of cell proliferation. DCs generated in the presence of FL expressed more costimulatory molecules on their surfaces and stimulated allogeneic T cell proliferation in MLR to a higher magnitude. Furthermore, FL partially antagonized IL-10-mediated inhibition on DCs function. Further characterization of FL actions may provide new and important information for immunotherapeutic approaches utilizing DCs.

Effects of porcine epidemic diarrhea virus on porcine monocyte-derived dendritic cells and intestinal dendritic cells

Infection with porcine epidemic diarrhea virus (PEDV) causes damage to intestinal epithelial cells and results in acute diarrhea and dehydration with high mortality rates in swine. Dendritic cells (DCs) are highly effective antigen-presenting cells widely distributed beneath the intestinal epithelium, thus making them an early target for virus contact. DCs uptake and present viral antigens to T cells, which then initiate a distinct immune response. In this study, we investigated how attenuated PEDV (CV777) affects the function of porcine monocyte-derived dendritic cells (Mo-DCs). Our results show that the expression of Mo-DC surface markers such as SWC3a(+)CD1a(+), SWC3a(+)CD80/86(+) and SWC3a(+)SLA-II-DR(+) is increased after infection with CV777 for 24 h. Mo-DCs infected with CV777 produce higher levels of IL-12 and INF-γ compared to mock-infected Mo-DCs but the expression profile for IL-10 does not change. Interactions between Mo-DCs and CV777 significantly influence the stimulation of the T cell response in vitro. Consistent with these results, after 48 h of CV777 infection, there is enhancement in the ability of porcine intestinal DCs to sample the antigen and activate T-cell proliferation in vivo. The enhancement of sampling and presentation is most pronounced for immature Mo-DCs. These results suggest that CV777 stimulates the ability of Mo-DCs to sample and present antigen. We conclude that CV777 may be a useful vaccine to trigger adaptive immunity.

MicroRNA-146a and microRNA-146b regulate human dendritic cell apoptosis and cytokine production by targeting TRAF6 and IRAK1 proteins

We have previously reported 27 differentially expressed microRNAs (miRNAs) during human monocyte differentiation into immature dendritic cells (imDCs) and mature DCs (mDCs). However, their roles in DC differentiation and function remain largely elusive. Here, we report that microRNA (miR)-146a and miR-146b modulate DC apoptosis and cytokine production. Expression of miR-146a and miR-146b was significantly increased upon monocyte differentiation into imDCs and mDCs. Silencing of miR-146a and/or miR-146b in imDCs and mDCs significantly prevented DC apoptosis, whereas overexpressing miR-146a and/or miR-146b increased DC apoptosis. miR-146a and miR-146b expression in imDCs and mDCs was inversely correlated with TRAF6 and IRAK1 expression. Furthermore, siRNA silencing of TRAF6 and/or IRAK1 in imDCs and mDCs enhanced DC apoptosis. By contrast, lentivirus overexpression of TRAF6 and/or IRAK1 promoted DC survival. Moreover, silencing of miR-146a and miR-146b expression had little effect on DC maturation but enhanced IL-12p70, IL-6, and TNF-α production as well as IFN-γ production by IL-12p70-mediated activation of natural killer cells, whereas miR-146a and miR-146b overexpression in mDCs reduced cytokine production. Silencing of miR-146a and miR-146b in DCs also down-regulated NF-κB inhibitor IκBα and increased Bcl-2 expression. Our results identify a new negative feedback mechanism involving the miR-146a/b-TRAF6/IRAK1-NF-κB axis in promoting DC apoptosis.

Loading dendritic cells with PLA-p24 nanoparticles or MVA expressing HIV genes induces HIV-1-specific T cell responses

Since recent data suggest that nanoparticles and modified vaccinia ankara (MVA) vectors could play a pivotal role in HIV-1 therapeutics and vaccine design, in an ex vivo model of human monocyte-derived dendritic cells (MDDCs), we compared two different loading strategies with HIV-1 vaccine vehicles, either viral or synthetic derived. We used polylactic acid (PLA) colloidal biodegradable particles, coated with HIV Gag antigens (p24), and MVA expressing Gag (rMVA-gag and rMVA-gag/trans membrane) or Tat, Nef and Rev genes (rMVA tat+rev and rMVA nef). PLA-p24 captured by MDDCs from HIV-1 individuals induced a slight degree of MDDC maturation, cytokine and chemokine secretion and migration towards a gradient of CCL19 chemokine and highly increased HIV-specific CD8(+) T-cell proliferation compared with p24 alone. After complete maturation induction of PLA-p24-pulsed MDDCs, maximal migration towards a gradient of CCL19 chemokine and induction of HIV-specific T-cell proliferation (two-fold higher for CD4(+) than CD8(+)) and cytokine secretion (IFN-γ and IL-2) in the co-culture were observed. Upon exposure to MVA-gag, MDDCs produced cytokines and chemokines and maintained their capacity to migrate to a gradient of CCL19. MDDCs infected with MVA-gag and MVA-gag trans-membrane were able to induce HIV-specific CD8(+) proliferation and secretion of IFN-γ, IL-2, IL-6 and TNF-α. We conclude that both HIV antigens loading strategies (PLA-p24 nanoparticles or MVA expressing HIV genes) induce HIV-1-specific T-cell responses, which are able to kill autologous gag-expressing cells. Thus, they are plausible candidates for the development of anti-HIV vaccines.

A suppressor of cytokine signaling 1 antagonist enhances antigen-presenting capacity and tumor cell antigen-specific cytotoxic T lymphocyte responses by human monocyte-derived dendritic cells

The suppressor of cytokine signaling 1 (SOCS1) has emerged as a critical inhibitory molecule for controlling the cytokine response and antigen presentation by dendritic cells (DCs), thereby regulating the magnitude of both innate and adaptive immunity. The aim of this study was to investigate whether the SOCS1 antagonist pJAK2(1001-1013) peptide can weaken or block the inhibition function of SOCS1 in DCs by evaluating the phenotype and cytokine production, antigen-presenting, and specific T-cell-activating capacities of DCs electroporated with human gastric cancer cell total RNA. Furthermore, STAT1 activation of the JAK/STAT signal pathway mediated by SOCS1 was analyzed by Western blotting. The results demonstrate that the SOCS1 antagonist pJAK2(1001-1013) peptide upregulated the expression of the maturation marker (CD83) and costimulatory molecule (CD86) of RNA-electroporated human monocyte-derived mature DCs (mDCs), potentiated the capacity of mDCs to induce T-cell proliferation, stimulated the secretion of proinflammatory cytokines, and enhanced the cytotoxicity of tumor cell antigen-specific CTLs activated by human gastric cancer cell total RNA-electroporated mDCs. Data from Western blot analysis indicate that STAT1 was further activated in pJAK2(1001-1013) peptide-loaded mDCs. These results imply that the SOCS1 antagonist pJAK2(1001-1013) peptide is an effective reagent for the enhancement of antigen-specific antitumor immunity by DCs.

Stimulating surface molecules, Th1-polarizing cytokines, proven trafficking--a new protocol for the generation of clinical-grade dendritic cells

BACKGROUND AIMS

Dendritic cells (DC) have been vigorously investigated as an immunological basis for therapeutic vaccination against cancer and infections, even among patients after allogeneic stem cell transplantation.

METHODS

Effective induction of cell-mediated immunity strongly depends on the ability of DC to (i) migrate to the draining lymphoid organs mediated by chemokine receptors, (ii) prime T cells through high expression of costimulatory molecules and major histocompatibility complexes and (iii) secret Th1-polarizing cytokines such as Interleukin-12 (IL-12). However, there is no protocol to generate fully matured and functional DC according to methodical requirements of current good manufacturing practice (CGMP) guidelines.

RESULTS

We established a protocol conforming to CGMP standards that permits the generation of fully matured and functional DC on the basis of cell culture in adherence bags with the use of serum-free media with a maturation cocktail, containing tumor necrosis factor-alpha/Interferon-alpha/polyinosinic:polycytidylic acid. Our DC superiorly display three critical features for an effective induction of cell-mediated immunity without evidence of exhaustion, along with its ability to prime infectious or tumor-specific T cells in a short-term cell culture.

CONCLUSIONS

Our newly developed protocol offers an attractive method to produce fully matured Th1-polarizing DC with proven migratory and stimulatory capacity for any clinical application according to CGMP standards.

Antitumor effects and mechanisms of dendritic cells stimulated by sCD40L on ovarian cancer cells in vitro

Objective

This study aimed to examine the expression of immune suppression factors and the mechanisms of antitumor effects of cord blood dendritic cells (DCs) stimulated by soluble cluster of differentiation 40 ligand (sCD40L) and cytokines in vitro in ovarian cancer patients.

Methods

The expression levels of interleukin (IL)-10 and transforming growth factor (TGF)-β messenger RNA in peripheral blood were detected by reverse transcription polymerase chain reaction; expression levels of CD80 and CD86 in DCs stimulated by sCD40L were detected using flow cytometry and confocal laser scanning microscopy.

Results

Expression levels of IL-10 and TGF-β genes in the peripheral blood of ovarian cancer patients were significantly increased compared with patients with benign ovarian tumors (P < 0.05). The expression levels of CD80 and CD86 in DCs cultured in the granulocyte-macrophage colony-stimulating factor + IL-4 + stem cell factor + Flt-3 ligand + sCD40L group were significantly increased compared with those in the control group, as assessed by flow cytometry and confocal laser scanning microscopy (P < 0.05).

Conclusion

A variety of cytokines in combination with sCD40L can promote the proliferation of cord blood-derived DCs and induce their maturation as well as stimulating a specific antitumor response.

Maturation of human iDCs by IL-18 plus PGE2, but not by each stimulus alone, induced migration toward CCL21 and the secretion of IL-12 and IFN-γ

Dendritic cells (DCs) are potent antigen-presenting cells that initiate the primary immune response and whose functional properties in vivo depend on the maturation stimulus. We describe the functional properties of human monocyte-derived DCs after the maturation of immature DCs (iDCs) for 2 days with LPS (100 ng/ml), PGE2 (1 μg/ml), CD40L (1 μg/ml) or IL-18 (200 ng/ml) and with CD40L+PGE2 and IL-18+PGE2 mixtures at the same concentrations as above. Neither IL-18 nor PGE2 alone stimulated IL-12 or IFN-γ secretion. When administered simultaneously to 1×10(6)iDCs/ml, IL-18+PGE2 induced the secretion of 131.4±6.7 pg IL-12/ml and 355±87 pg IFN-γ/ml but there was no detectable IL-10 secretion. However, PGE2 alone stimulated the secretion of 208±89 pg IL-10/ml whereas IL-18 alone did not stimulate the secretion of IL-10, IL-12, TNF-α or INF-γ. When the mixture of CD40L+PGE2 was used, only migration toward CCL19 and CCL21 was induced. CD40L did not stimulate the secretion of IL-10, IL-12, TNF-α or IFN-γ and did not stimulate migration toward CCL19 or CCL21. The extent of stimulation of T cell proliferation was essentially the same for all stimuli at the concentrations given above. New properties such as IL-12 and INF-γ secretion and migration toward CCL21 emerged when a mixture of IL-18+PGE2 was employed. These data show that when the pairs of stimuli reported here were used simultaneously their effect was not additive. This system can be used to prepare mDCs with properties useful for cell therapy and also as a model to investigate the mechanisms of cytokine secretion and cell migration.

DCs pulsed with novel HLA-A2-restricted CTL epitopes against hepatitis C virus induced a broadly reactive anti-HCV-specific T lymphocyte response

Objective

To determine the capacity of dendritic cells (DCs) loaded with single or multiple-peptide mixtures of novel hepatitis C virus (HCV) epitopes to stimulate HCV-specific cytotoxic T lymphocyte (CTL) effector functions.

Methods

A bioinformatics approach was used to predict HLA-A2-restricted HCV-specific CTL epitopes, and the predicted peptides identified from this screen were synthesized. Subsequent IFN-γ ELISPOT analysis detected the stimulating function of these peptides in peripheral blood mononuclear cells (PBMCs) from both chronic and self-limited HCV infected subjects (subjects exhibiting spontaneous HCV clearance). Mature DCs, derived in vitro from CD14⁺ monocytes harvested from the study subjects by incubation with appropriate cytokine cocktails, were loaded with novel peptide or epitope peptide mixtures and co-cultured with autologous T lymphocytes. Granzyme B (GrB) and IFN-γ ELISPOT analysis was used to test for epitope-specific CTL responses. T-cell-derived cytokines contained in the co-cultured supernatant were detected by flow cytometry.

Results

We identified 7 novel HLA-A2-restricted HCV-specific CTL epitopes that increased the frequency of IFN-γ-producing T cells compared to other epitopes, as assayed by measuring spot forming cells (SFCs). Two epitopes had the strongest stimulating capability in the self-limited subjects, one found in the E2 and one in the NS2 region of HCV; five epitopes had a strong stimulating capacity in both chronic and self-limited HCV infection, but were stronger in the self-limited subjects. They were distributed in E2, NS2, NS3, NS4, and NS5 regions of HCV, respectively. We also found that mDCs loaded with novel peptide mixtures could significantly increase GrB and IFN-γ SFCs as compared to single peptides, especially in chronic HCV infection subjects. Additionally, we found that DCs pulsed with multiple epitope peptide mixtures induced a Th1-biased immune response.

Conclusions

Seven novel and strongly stimulating HLA-A2-restricted HCV-specific CTL epitopes were identified. Furthermore, DCs loaded with multiple-epitope peptide mixtures induced epitope-specific CTLs responses.

Poly I: C-activated dendritic cells that were generated in CellGro for use in cancer immunotherapy trials

Background

For clinical applications, dendritic cells (DCs) need to be generated using GMP-approved reagents. In this study, we tested the characteristics of DCs generated in two clinical grade culture media and activated by three maturation stimuli, Poly I: C, LPS and the mixture of proinflammatory cytokines in order to identify the optimal combination of culture media and activation stimulus for the clinical use.

Method

We tested DCs generation using two GMP-certified culture media, CellGro and RPMI+5% human AB serum and evaluated DCs morphology, viability and capapability to mature. We tested three maturation stimuli, PolyI:C, LPS and the mixture of proinflammatory cytokines consisting of IL-1, IL-6, TNF and prostaglandin E2. We evaluated the capacity of activated DCs to induce antigen-specific T cells and regulatory T lymphocytes.

Results

Cell culture in CellGro resulted in a higher yield of immature DCs resulting from increased number of adherent monocytes. DCs that were generated in CellGro and activated using Poly I:C were the most efficient in expanding antigen-specific T cells compared to the DCs that were generated in other media and activated using LPS or the cocktail of proinflammatory cytokines. A comparison of all tested combinations revealed that DCs that were generated in CellGro and activated using Poly I:C induced low numbers of regulatory T cells.

Conclusion

In this study, we identified monocyte-derived DCs that were generated in CellGro and activated using Poly I:C as the most potent clinical-grade DCs for the induction of antigen-specific T cells.

Bromelain treatment leads to maturation of monocyte-derived dendritic cells but cannot replace PGE2 in a cocktail of IL-1β, IL-6, TNF-α and PGE2

Immunotherapy using dendritic cells (DC) has shown promising results. However, the use of an appropriate DC population is critical for the outcome of this treatment, and the search for an optimal DC subset is still ongoing. The DC used in immunotherapy today are usually matured with a cytokine cocktail consisting of TNF-α, IL-1β, IL-6 and PGE(2). These cells have deficits in their cytokine production, particularly IL-12p70, mainly because of the presence of PGE(2). Bromelain is a pineapple stem extract containing a mixture of proteases that has been used clinically in adjuvant cancer treatment. In this study, we analysed the effect of bromelain on human monocyte-derived DC. We added bromelain to the cytokine cocktail and modified cytokine cocktails with either no PGE(2) or reduced amounts of PGE(2), respectively. Combining bromelain with the cytokine cocktails containing PGE(2) resulted in an increased surface expression of CD83, CD80 and CD86. The chemokine receptor CCR7 was also considerably upregulated in these DC populations compared with DC treated with the cytokine cocktail alone. Removal or reduction of PGE(2) from the cytokine cocktail did not increase the IL-12p70 secretion from stimulated DC, and addition of bromelain to the different cytokine cocktails resulted in only a minor increase in IL-12p70 production. Moreover, combining bromelain with the cytokine cocktails did not improve the T cell stimulatory capacity of the generated DC populations. In conclusion, bromelain treatment of monocyte-derived DC does not improve the functional quality compared with the standard cytokine cocktail.

Dendritic cells exposed to MVA-based HIV-1 vaccine induce highly functional HIV-1-specific CD8(+) T cell responses in HIV-1-infected individuals

Currently, MVA virus vectors carrying HIV-1 genes are being developed as HIV-1/AIDS prophylactic/therapeutic vaccines. Nevertheless, little is known about the impact of these vectors on human dendritic cells (DC) and their capacity to present HIV-1 antigens to human HIV-specific T cells. This study aimed to characterize the interaction of MVA and MVA expressing the HIV-1 genes Env-Gag-Pol-Nef of clade B (referred to as MVA-B) in human monocyte-derived dendritic cells (MDDC) and the subsequent processes of HIV-1 antigen presentation and activation of memory HIV-1-specific T lymphocytes. For these purposes, we performed ex vivo assays with MDDC and autologous lymphocytes from asymptomatic HIV-infected patients. Infection of MDDC with MVA-B or MVA, at the optimal dose of 0.3 PFU/MDDC, induced by itself a moderate degree of maturation of MDDC, involving secretion of cytokines and chemokines (IL1-ra, IL-7, TNF-α, IL-6, IL-12, IL-15, IL-8, MCP-1, MIP-1α, MIP-1β, RANTES, IP-10, MIG, and IFN-α). MDDC infected with MVA or MVA-B and following a period of 48 h or 72 h of maturation were able to migrate toward CCL19 or CCL21 chemokine gradients. MVA-B infection induced apoptosis of the infected cells and the resulting apoptotic bodies were engulfed by the uninfected MDDC, which cross-presented HIV-1 antigens to autologous CD8⁺ T lymphocytes. MVA-B-infected MDDC co-cultured with autologous T lymphocytes induced a highly functional HIV-specific CD8⁺ T cell response including proliferation, secretion of IFN-γ, IL-2, TNF-α, MIP-1β, MIP-1α, RANTES and IL-6, and strong cytotoxic activity against autologous HIV-1-infected CD4⁺ T lymphocytes. These results evidence the adjuvant role of the vector itself (MVA) and support the clinical development of prophylactic and therapeutic anti-HIV vaccines based on MVA-B.

Maturation of monocyte derived dendritic cells with OK432 boosts IL-12p70 secretion and conveys strong T-cell responses

Background

Design of tumour specific immunotherapies using the patients' own dendritic cells (DC) is a fast advancing scientific field. The functional qualities of the DC generated in vitro are critical, and today's gold standard for maturation is a cytokine cocktail consisting of IL-1β, IL-6, TNF-α and PGE₂ generating cells lacking IL-12p70 production. OK432 is an immunotherapeutic agent derived from killed Streptococcus pyogenes that has been used clinically to treat malignant and benign neoplasms for decades.

Methods

In this study, we analysed the effects of OK432 on DC maturation, DC migration, cytokine and chemokine secretion as well as T-cell stimulatory capacity, and compared it to the cytokine cocktail alone and combinations of OK432 with the cytokine cocktail.

Results

OK432 induced a marked up-regulation of CD40 on the cell surface as well as a strong inflammatory response from the DC with significantly more secretion of 19 different cytokines and chemokines compared to the cytokine cocktail. Interestingly, secretion of IL-15 and IL-12p70 was detected at high concentrations after maturation of DC with OK432. However, the OK432 treated DC did not migrate as well as DC treated with cytokine cocktail in a transwell migration assay. During allogeneic T-cell stimulation OK432 treated DC induced proliferation of over 50 percent of CD4 and 30 percent of CD8 T-cells for more than two cell divisions, whereas cytokine cocktail treated DC induced proliferation of 12 and 11 percent of CD4 and CD8 T-cells, respectively.

Conclusions

The clinically approved compound OK432 has interesting properties that warrants its use in DC immunotherapy and should be considered as a potential immunomodulating agent in cancer immunotherapy.

Epithelial cells from smokers modify dendritic cell responses in the context of influenza infection

Epidemiologic evidence suggests that cigarette smoking is a risk factor for infection with influenza, but the mechanisms underlying this susceptibility remain unknown. To ascertain if airway epithelial cells from smokers demonstrate a decreased ability to orchestrate an influenza-induced immune response, we established a model using differentiated nasal epithelial cells (NECs) from nonsmokers and smokers, co-cultured with peripheral blood monocyte-derived dendritic cells (mono-DCs) from nonsmokers. NEC/mono-DC co-cultures were infected with influenza A virus and analyzed for influenza-induced immune responses 24 hours after infection. We observed that NECs from smokers, as well as mono-DCs co-cultured with NECs from smokers, exhibited suppressed influenza-induced, interferon-related proteins interferon regulatory factor-7, Toll-like receptor-3, and retinoic acid inducible gene-1, likely because of the suppressed production of IFNα from the NECs of smokers. Furthermore, NEC/mono-DC co-cultures using NECs from smokers exhibited suppressed concentrations of T-cell/natural killer cell chemokine interferon gamma-induced protein 10 (IP-10) after infection with influenza, indicating that NECs from smokers may skew early influenza-induced Th1 responses. In contrast, NEC/mono-DC co-cultures using NEC from smokers contained increased influenza-induced concentrations of the Th2 chemokine thymic stromal lymphopoeitin (TSLP). In addition, NECs from smokers cultured alone had increased influenza-induced concentrations of the Th2 chemokine thymus and activation-regulated chemokine (TARC). Using this model, we demonstrated that in the context of infection with influenza, NECs obtained from smokers create an overall cytokine microenvironment that suppresses the interferon-mediated Th1 response and enhances the TSLP-TARC-mediated Th2 response, with the potential to modify the responses of DCs. Smoking-induced alterations in the Th1/Th2 balance may play a role in developing underlying susceptibilities to respiratory viral infections, and may also promote the likelihood of acquiring Th2 proallergic diseases.