T-cell Induction Research Articles

Leptin and ghrelin regulate dendritic cell maturation and dendritic cell induction of regulatory T-cells.

Leptin and ghrelin regulate dendritic cell maturation and dendritic cell induction of regulatory T-cells.

HLA-DRB and HLA-DQ genetic variability in patients with aspirin-exacerbated respiratory disease.

Major histocompatibility complex (MHC) class II is involved in T-cell activation, cytokine secretion, and induction of immune responses. Cytokines, staphylococcus super antigens, and eosinophil activation are proposed to play important roles in aspirin-exacerbated respiratory disease (AERD). This study is aimed at investigating the association of HLA-DRB and DQ genetic variabilities in patients with AERD. A genetic association analysis in three different groups, including 33 patients with AERD, 17 patients with aspirin-tolerant asthma (ATA), and 100 healthy controls was performed. Oral aspirin challenge (OAC) test was performed to identify aspirin hypersensitivity. Pulmonary function test (PFT) was performed for all patients. Eosinophil percentage in nasal smear and peripheral blood and serum immunoglobin (Ig)E were investigated. HLA-DRB, HLA-DQA1, and HLA-DQB1 were genotyped using polymerase chain reaction. HLA-DQB1*0302 (OR, 5.49, 95% confidence interval [CI],(2.40-12.59)), HLA-DQA1*0301 (OR, 2.90, 95% CI, (1.49-5.67)), HLA-DRB4 (OR, 2.94, 95% CI, (1.61-5.36)), and HLA-DRB1*04 (OR, 3.19, 95% CI, (1.57-6.47)) were higher in patients with AERD compared with controls. In patients with AERD, HLA-DQB1*0301 (OR,0.22, 95% CI, (0.09-0.54)), HLA-DQA1*0501 (OR, 0.42, 95% CI, (0.21-0.81)), HLA-DRB1*11 (OR, 0.30, 95% CI, (0.12-0.73)), and HLA-DRB3 (OR, 0.38, 95% CI, (0.21-0.70)) were significantly lower compared with healthy controls. Patients with AERD had lower frequencies of HLA-DQB1*0301 (OR, 0.27, 95% CI, (0.08-0.86)), and HLA-DRB1*011 (OR, 0.27, 95% CI, (0.08-0.86)) compared with ATA. Haplotypes of HLA-DRB1*04/ DQA1*0301/ DQB1*0302 (OR, 4.25, 95% CI, (1.94-9.29)) and HLA-DRB1*07 /DQA1*0201/ DQB1*0201 (OR, 3.52, 95% CI, (1.54-8.06)) were higher in patients with AERD compared with controls (all p < 0.05). Results of this study suggest that HLA-DQB1*0302 and HLA-DRB1*04 and their related haplotypes are genes involved in predisposing patients to AERD, whereas HLA-DQB1*0301 and HLA-DRB1*011 have negative association with AERD.

N-3-(oxododecanoyl)-L-homoserine lactone promotes the induction of regulatory T-cells by preventing human dendritic cell maturation.

N-3-(Oxododecanoyl)-L-homoserine lactone (C12) is a small bacterial signaling molecule secreted by Pseudomonas aeruginosa (PA), which activates mammalian cells through TLR4-independent mechanisms. C12 acts as an immunosuppressant and it has been shown to modulate murine bone marrow-derived dendritic cell-mediated T-helper 2 (Th2) cell polarizations invitro. In the present study, we initially examined the impact of C12 on the maturation of human monocyte-derived dendritic cells (Mo-DCs) and the induction of regulatory T-cells (iTregs) in culture. Our findings demonstrate that C12-treated Mo-DCs failed to undergo lipopolysaccharide (LPS)-induced maturation. At the molecular level, C12 blocked the upregulation of surface molecules, including CD11c, HLA-DR, CD40, and CD80, and it switched to an interleukin (IL)-10(high), IL-12p70(low) phenotype. Moreover, C12 selectively inhibited the capacity of Mo-DCs to stimulate the proliferation of allogeneic CD4(+) T-cells. Otherwise, the C12-treated Mo-DCs promoted the generation of CD4(+)CD25(+)Foxp3(+)-induced regulatory T-cells (iTregs) and enhanced their IL-10 and transforming growth factor (TGF)-β production associated with reduced interferon (IFN)-γ and IL-12p70 production. These findings provide new insights towards understanding the persistence of chronic inflammation in PA infection.

ITOC2 – 032. Optimising active-specific immunotherapy in lymphodepleted mice with subcutaneous melanoma

Background Lymphodepletion, reconstitution and active-specific tumour cell vaccination (LRAST) enhances the tumour-specific immune response in a murine melanoma model. Myeloid derived suppressor cells (MDSC, Gr-1+ CD11b+) may decrease the induction of T-cells and their therapeutic efficacy. Aim of the study was to evaluate the benefit of MDSC depletion in addition to LRAST, using anti-Gr-1 antibody (Ab). The Gr-1 epitope is also expressed on CD8+ T-cells. Methods Female C57BL/6 mice with subcutaneous (s.c.) D5 melanoma were lymphodepleted with cyclophosphamide and reconstituted with naive splenocytes. Vaccination was performed with irradiated syngeneic mGM-CSF-producing D5G6 melanoma cells. For MDSC depletion, anti-Gr-1 Ab (clone RB6-8C5, 230 μg) was injected every other day starting on the day of lymphodepletion. Induction of tumour-specific T-cells in tumour vaccine draining lymph nodes was evaluated using interferon (IFN)- γ assays. Immune cells were analysed by flow cytometry. D5 tumour growth was monitored. Results Anti-Gr-1 administration had no long-lasting effect on MDSC elimination. The antibody also bound to CD8+ Gr-1+ CD44+ T memory cells. The combination of anti-Gr-1 treatment and LRAST enhanced tumour-specific IFN- γ release. Nevertheless, this did not translate into improved survival. Conclusions Given an insufficient elimination of MDSC and the possible depletion of Gr-1+ memory T-cells, the use of anti-Gr-1 Ab in our tumour model seems questionable.

A phase I/II study of OTSGC-A24 combined peptide vaccine in advanced gastric cancer.

65 Background: The aim of this study was to evaluate the safety and optimal dosing schedule of a HLA-restricted cancer vaccine cocktail, OTSGC-A24 targeting novel specific tumor antigens FOXM1, DEPDC1, KIF20A, URLC10 and VEGFR1 in advanced gastric cancer patients with HLA-2402 haplotype. Methods: The vaccine was administered subcutaneously at 3-weekly, 2-weekly and weekly interval. In the first phase, 3 evaluable patients were treated in each dose cohort. The decision to expand the 2-weekly and weekly cohort to 10 patients per cohort was based on specific cytotoxic T-lymphocyte (CTL) induction rate using ELISPOT assay 4 weeks after vaccination. Results: The vaccine was well tolerated at all dose cohorts. The most common toxicity seen was skin induration at the injection sites. No DLT was observed. One patient developed G2 interstitial pneumonitis, 6 months after initiation of treatment. Stable disease was seen in 4 of 9 evaluable patients. The specific CTL induction can be observed at 4 weeks post vaccination with the highest (&gt;2 of 3) observed in the weekly and 2-weekly cohorts. One of 3 patients in the 3-weekly cohort achieved specific CTL response at 4 weeks post vaccination, although all patients attained specific CTL response by 12 weeks after vaccination. Conclusions: OTSGC-A24 combined peptide vaccine was well tolerated. At 4 weeks post vaccination, the CTL induction rate is superior in the weekly and 2-weekly cohort. Efficacy data of the expanded cohorts will be presented. Clinical trial information: NCT01227772.

Molecules Great and Small: The Complement System.

The complement cascade, traditionally considered an effector arm of innate immunity required for host defense against pathogens, is now recognized as a crucial pathogenic mediator of various kidney diseases. Complement components produced by the liver and circulating in the plasma undergo activation through the classical and/or mannose-binding lectin pathways to mediate anti-HLA antibody-initiated kidney transplant rejection and autoantibody-initiated GN, the latter including membranous glomerulopathy, antiglomerular basement membrane disease, and lupus nephritis. Inherited and/or acquired abnormalities of complement regulators, which requisitely limit restraint on alternative pathway complement activation, contribute to the pathogenesis of the C3 nephropathies and atypical hemolytic uremic syndrome. Increasing evidence links complement produced by endothelial cells and/or tubular cells to the pathogenesis of kidney ischemia-reperfusion injury and progressive kidney fibrosis. Data emerging since the mid-2000s additionally show that immune cells, including T cells and antigen-presenting cells, produce alternative pathway complement components during cognate interactions. The subsequent local complement activation yields production of the anaphylatoxins C3a and C5a, which bind to their respective receptors (C3aR and C5aR) on both partners to augment effector T-cell proliferation and survival, while simultaneously inhibiting regulatory T-cell induction and function. This immune cell-derived complement enhances pathogenic alloreactive T-cell immunity that results in transplant rejection and likely contributes to the pathogenesis of other T cell-mediated kidney diseases. C5a/C5aR ligations on neutrophils have additionally been shown to contribute to vascular inflammation in models of ANCA-mediated renal vasculitis. New translational immunology efforts along with the development of pharmacologic agents that block human complement components and receptors now permit testing of the intriguing concept that targeting complement in patients with an assortment of kidney diseases has the potential to abrogate disease progression and improve patient health.

Microrna-17-92 Cluster: Novel Target for Controlling Gvhd While Preserving GVL Effect

Graft-versus-host disease (GVHD) remains a life threatening complication after allogeneic hematopoietic stem cell transplantation (HCT). Donor T cells are the key pathogenic effectors in the induction of GVHD. MicroRNAs (miRs) have been shown to play an important role in orchestrating immune response, among which miR-17-92 cluster is one of the best characterized miR clusters that encodes 6 miRs including 17, 18a, 19a, 20a, 19b-1 and 92-1. Although regulatory functions of miR-17-92 cluster have been elaborated in a variety of immune responses including anti-infection, anti-tumor, and autoimmunity, the role of this miR cluster in the modulation of T-cell response to alloantigens and the development of GVHD has not been explored previously. Based on the previous report that miR-17-92 promotes Th1 responses and inhibits induced regulatory T-cell (iTreg) differentiation in vitro, we hypothesized that blockade of miR-17-92 would constrain T-cell alloresponse and attenuate GVHD.To evaluate the function of miR-17-92 on T-cell alloresponse, we utilized the mice with miR-17-92 conditional knock-out (KO) on T cells as donors, and compared the alloresponse of WT and KO T cells after allogeneic bone marrow transplantation (allo-BMT). We observed that KO T cells had substantially reduced ability to proliferate and produce IFNγ as compared to WT counterparts 4 days after cell transfer. Interestingly, CD4 but not CD8 KO T cells had increased cell death in the population of fast-dividing T cells. Thus, miR-17-92 cluster promotes activation and expansion of both CD4 and CD8 T cells, and inhibits activation-induced cell death of CD4 but not CD8 T cells at the early stage of alloresponse in vivo. We further evaluated the role of miR-17-92 on T cells in the development of acute GVHD in a fully MHC-mismatched BMT model. In sharp contrast to WT T cells that caused severe GVHD and resulted in 100% mortality of the recipients, KO T cells were impaired in causing severe GVHD reflected by mild clinical manifestations and no mortality. These observations were extended to MHC-matched but minor antigen-mismatched as well as haploidentical BMT models that are more clinically relevant. We next addressed the critical question whether T cells deficient for miR-17-92 are still capable of mediating graft-versus-leukemia (GVL) effect. Using A20 lymphoma and P815 mastocytoma cell lines, we demonstrated that the KO T cells essentially retained the GVL activity in MHC-mismatched and haploidentical BMT model, respectively.Mechanistic studies revealed that miR-17-92 promoted CD4 T-cell proliferation, survival, migration to target organs, and Th1-differentiation, but reduced Th2-differentiation and iTreg generation. However, miR-17-92 had less impact on CD8 T-cell proliferation, survival, IFNγ production, and cytolytic activity reflected by granzyme B and CD107a expression. Moreover, miR-17-92 negatively regulated TNFα production by both CD4 and CD8 T cells. We therefore conclude that miR-17-92 cluster is required for T cells to induce severe GVHD, but it is dispensable for T cells to mediate the GVL effect.To increase translational potential of our findings, we designed the locked nucleic acid (LNA) antagomirs specific for miR-17 or miR-19, which have been reported to be the key members in this cluster. We observed that the treatment with anti-miR-17 significantly inhibited T-cell expansion and IFNγ production in response to alloantigen in vivo, and anti-miR-19 was more effective. Furthermore, our ongoing experiment showed the treatment with anti-miR-17 or anti-miR-19 was able to considerably attenuate the severity of GVHD as compared to scrambled antagomir in a MHC-mismatched BMT model.Taken together, the current work reveals that miR-17-92 cluster is essential for T-cell alloresponse and GVHD development, and validates miR-17-92 cluster as promising therapeutic target for the control of GVHD while preserving GVL activity in allogeneic HCT. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

Squalene emulsion potentiates the adjuvant activity of the TLR4 agonist, GLA, via inflammatory caspases, IL-18, and IFN-γ.

The synthetic TLR4 agonist glucopyranosyl lipid adjuvant (GLA) is a potent Th1-response-inducing adjuvant when formulated in a squalene oil-in-water emulsion (SE). While the innate signals triggered by TLR4 engagement are well studied, the contribution of SE remains unclear. To better understand the effect of SE on the adjuvant properties of GLA-SE, we compared the innate and adaptive immune responses elicited by immunization with different formulations: GLA without oil, SE alone or the combination, GLA-SE, in mice. Within the innate response to adjuvants, only GLA-SE displayed features of inflammasome activation, evidenced by early IL-18 secretion and IFN-γ production in memory CD8(+) T cells and neutrophils. Such early IFN-γ production was ablated in caspase-1/11(-/-) mice and in IL-18R1(-/-) mice. Furthermore, caspase-1/11 and IL-18 were also required for full Th1 CD4(+) T-cell induction via GLA-SE. Thus, we demonstrate that IL-18 and caspase-1/11 are components of the response to immunization with the TLR4 agonist/squalene oil-in-water based adjuvant, GLA-SE, providing implications for other adjuvants that combine oils with TLR agonists.

A Stable Nanoparticulate DDA/MMG Formulation Acts Synergistically with CpG ODN 1826 to Enhance The CD4 + T-Cell Response

To combine the dimethyldioctadecyl ammonium/monomycoloyl glycerol (DDA/MMG) liposomal vaccine adjuvant with the Toll-like receptor (TLR) ligands poly(I:C) (TLR3), flagellin (TLR5) or CpG oligodeoxynucleotide 1826 (TLR9) and investigate their physicochemical properties as well as their CD4(+) T-cell-inducing capacity. Formulations were investigated by dynamic light scattering and differential scanning calorimetry. Their CD4(+) T-cell induction with a tuberculosis antigen was analyzed by multiplex cytokine analysis, ELISA and intracellular cytokine staining. DDA/MMG/CpG was the best combination for obtaining increased CD4(+) T-cell responses. However, coformulating CpG and DDA/MMG liposomes led to instability and the formulation was therefore optimized systematically using a design of experiment. The nanoparticulate DDA/MMG/CpG adjuvant can be stabilized and synergistically enhances CD4(+) T-cell responses compared with DDA/MMG liposomes.

Silica nanoparticles as the adjuvant for the immunisation of mice using hepatitis B core virus-like particles.

Advances in nanotechnology and nanomaterials have facilitated the development of silicon dioxide, or Silica, particles as a promising immunological adjuvant for the generation of novel prophylactic and therapeutic vaccines. In the present study, we have compared the adjuvanting potential of commercially available Silica nanoparticles (initial particles size of 10–20 nm) with that of aluminium hydroxide, or Alum, as well as that of complete and incomplete Freund's adjuvants for the immunisation of BALB/c mice with virus-like particles (VLPs) formed by recombinant full-length Hepatitis B virus core (HBc) protein. The induction of B-cell and T-cell responses was studied after immunisation. Silica nanoparticles were able to adsorb maximally 40% of the added HBc, whereas the adsorption capacity of Alum exceeded 90% at the same VLPs/adjuvant ratio. Both Silica and Alum formed large complexes with HBc VLPs that sedimented rapidly after formulation, as detected by dynamic light scattering, spectrophotometry, and electron microscopy. Both Silica and Alum augmented the humoral response against HBc VLPs to the high anti-HBc level in the case of intraperitoneal immunisation, whereas in subcutaneous immunisation, the Silica-adjuvanted anti-HBc level even exceeded the level adjuvanted by Alum. The adjuvanting of HBc VLPs by Silica resulted in the same typical IgG2a/IgG1 ratios as in the case of the adjuvanting by Alum. The combination of Silica with monophosphoryl lipid A (MPL) led to the same enhancement of the HBc-specific T-cell induction as in the case of the Alum and MPL combination. These findings demonstrate that Silica is not a weaker putative adjuvant than Alum for induction of B-cell and T-cell responses against recombinant HBc VLPs. This finding may have an essential impact on the development of the set of Silica-adjuvanted vaccines based on a long list of HBc-derived virus-like particles as the biological component.

Immunoglobulin heavy-chain-binding protein (BiP): a stress protein that has the potential to be a novel therapy for rheumatoid arthritis.

Immunoglobulin heavy-chain-binding protein (BiP) or glucose-regulated protein 78 (Grp78) is a vital ubiquitous resident of the endoplasmic reticulum (ER). As an intracellular chaperone, BiP correctly folds nascent polypeptides within the ER and regulates the unfolded protein response ensuring protection of the cell from denatured protein and reinforcing its anti-apoptotic role, when the cell is under stress. Additionally, BiP is a member of the heat-shock protein (HSP) 70 family and, as a stress protein, is up-regulated by conditions of reduced oxygen and glucose. Cell stress induces surface expression and secretion of BiP. Consequently, BiP is detectable in several bodily fluids including serum, synovial fluid (SF) and oviductal fluid. However, as an extracellular protein, BiP has additional properties that are quite distinct from the intracellular functions. Extracellular BiP is immunoregulatory and anti-inflammatory causing development of tolerogenic dendritic cells (DCs), induction of regulatory T-cells, abrogation of osteoclast development and function, induction of anti-inflammatory cytokine production, including interleukin (IL)-10, IL-1 receptor antagonist and soluble tumour necrosis factor (TNF)-receptor typeII, and attenuation of TNFα and IL-6. Together, these functions help drive the resolution of inflammation. Disease models of inflammatory arthritis have helped to demonstrate the novel mode of action of BiP in which the pharmacokinetics and pharmacodynamics are dissociated. The three murine models to be discussed each show BiP induced long-term therapeutic protection and therefore has potential for long-lasting drug-free therapy in rheumatoid arthritis (RA).

Optimizing parallel induction of HIV type 1-specific antibody and T-cell responses by multicomponent subunit vaccines.

Protection against HIV type 1 (HIV-1) infection/AIDS will likely require concerted actions of protective CD8(+) killer T cells and protective antibodies. The challenges in inducing such effectors by active immunization are such that the T-cell and antibody vaccine components require separate development. Here, a rational attempt is taken to combine two separately optimized heterologous regimens into a single T-cell-inducing and antibody-inducing vaccination schedule with minimal induction of unprotective Env-specific T cells. Clade A BG505 Env-derived uncleaved gp140 (BG505u) and conserved region tHIVc immunogens were utilized and presented to the immune system using non-replicating simian (chimpanzee) adenovirus ChAdV-63 (C) and poxvirus-modified vaccinia virus Ankara MVA (M). In addition, purified BG505 gp120 (P) was used for antibody induction. BALB/c mice were vaccinated to elicit Env antibodies alone using ChAdV63.BG505u. MVA.BG505u and BG505 gp120 in regimens CMP, CPP and PPP, and in combination with the ChAdV63.tHIVc and MVA.tHIVc components in regimens CMP+CMM, CPP+CMM and PPP+CMM. Antibody and T-cell responses to BG505 Env and conserved regions of the HIV-1 proteome were determined. Although all three regimens delivering BG505 Env induced similar levels of antibodies, BG505-specific T cells were induced in the CMP>CPP>PPP hierarchy, which was maintained during coinduction of tHIVc-specific T cells. Adjuvanted BG505 PPP decreased induction of tHIVc-specific T cells and tHIVc T-cell induction decreased induction of BG505 Ab. As expected, the antibodies that were induced neutralized tier 1 HIV-1 strains. These results inform designs of initial human studies combining separately optimized T-cell and B-cell HIV-1 vaccines into a single regimen.

Enhanced anti-tumor effects of the PD-1/PD-L1 blockade by combining a highly absorptive form of NF-kB/STAT3 inhibitor curcumin

The PD-1/PD-L1 blockade is now recognized as one of the basic immune interventions for development of combination cancer immunotherapy. We have been screening chemical libraries to obtain compounds which have an activity to augment anti-tumor activity of the PD-1/PD-L1 blockade. We have previously shown that activation of NF-kB and STAT3 signals in both cancer cells and immune cells plays important roles in cancer cell-induced immunosuppression, and their inhibition may augment anti-tumor CTL. Curcumin, a major active component of turmeric, has activities to inhibit both NF-kB and STAT3 signals. We have recently developed a highly absorptive form of curcumin which oral administration resulted in high plasma concentration. In this study, we evaluated combination treatment of this highly absorptive form of curcumin with the PD-1/PD-L1 blockade. Curcumin inhibited significantly in vitro production of IL6 and IL8 by human ovarian cancer cell lines (OC) having activated NF-kB and STAT3 signaling. In nude mice implanted with human OC, T-cell stimulatory activity of murine DC was impaired partly through increased human IL-6 from human OC. Systemic p.o. administration of curcumin decreased human IL6 in mouse serum and restored T-cell stimulatory activity of murine DC in spleens and tumors. In two syngeneic murine colon cancer models, NF-kB dependent IL6 producing MC38 in B6 mice and NF-kB non-activated IL6 non-producing CT26 in Balb/C mice, curcumin p.o. administration resulted in the significant augmentation of tumor antigen-specific CD8+ T-cell induction accompanied by increased T-cell stimulatory activity of DC via decreased STAT3 and NF-kB signaling, although curcumin did not inhibit proliferation of both tumor cell lines. Furthermore, p.o. administration of curcumin into non-tumor bearing B6 mice immunized with ovalbumin (OVA) peptide augmented OVA-specific CTL induction. These results indicate that curcumin not only enhances tumor antigen specific T-cell via reversal of tumor-induced immunosuppression (e.g. IL6 induced DC impairment), but also enhances CTL via directly acting on immune cells. Since PD-1 positive T cells were infiltrated in tumors expressing PD-L1, we evaluated combination of curcumin and anti-PD-L1 blockade, and found that combination of curcumin and anti-PD-L1 Ab had synergistic anti-tumor activity. These results indicate that combination of curcumin which enhances induction of tumor antigen specific, PD-1 positive CTL in tumors via acting on both cancer cells and immune cells and local PD-1/PD-L1 blockade, is an attractive strategy for development of effective cancer immunotherapy.

Vaccine-induced CD107a+ CD4+ T cells are resistant to depletion following AIDS virus infection.

CD4(+) T-cell responses are crucial for effective antibody and CD8(+) T-cell induction following virus infection. However, virus-specific CD4(+) T cells can be preferential targets for human immunodeficiency virus (HIV) infection. HIV-specific CD4(+) T-cell induction by vaccination may thus result in enhancement of virus replication following infection. In the present study, we show that vaccine-elicited CD4(+) T cells expressing CD107a are relatively resistant to depletion in a macaque AIDS model. Comparison of virus-specific CD107a, macrophage inflammatory protein-1β, gamma interferon, tumor necrosis factor alpha, and interleukin-2 responses in CD4(+) T cells of vaccinated macaques prechallenge and 1 week postchallenge showed a significant reduction in the CD107a(-) but not the CD107a(+) subset after virus exposure. Those vaccinees that failed to control viremia showed a more marked reduction and exhibited significantly higher viral loads at week 1 than unvaccinated animals. Our results indicate that vaccine-induced CD107a(-) CD4(+) T cells are depleted following virus infection, suggesting a rationale for avoiding virus-specific CD107a(-) CD4(+) T-cell induction in HIV vaccine design. Induction of effective antibody and/or CD8(+) T-cell responses is a principal vaccine strategy against human immunodeficiency virus (HIV) infection. CD4(+) T-cell responses are crucial for effective antibody and CD8(+) T-cell induction. However, virus-specific CD4(+) T cells can be preferential targets for HIV infection. Here, we show that vaccine-induced virus-specific CD107a(-) CD4(+) T cells are largely depleted following infection in a macaque AIDS model. While CD4(+) T-cell responses are important in viral control, our results indicate that virus-specific CD107a(-) CD4(+) T-cell induction by vaccination may not lead to efficient CD4(+) T-cell responses following infection but rather be detrimental and accelerate viral replication in the acute phase. This suggests that HIV vaccine design should avoid virus-specific CD107a(-) CD4(+) T-cell induction. Conversely, this study found that vaccine-induced CD107a(+) CD4(+) T cells are relatively resistant to depletion following virus challenge, implying that induction of these cells may be an alternative approach toward HIV control.

Abstract 183: Immune dysfunction cascades caused by ALCAM+ mesenchymal stem cells toward tumor progression

Abstract Purposes: We have been investigating the interplay between cancer cells and host immunity, and previously demonstrated that Snail expression in tumor cells accelerates metastasis not only by enhancing tumor motility but also by inducing immune dysfunction through increase of a variety of immunoregulatory cells using murine tumor models implanted with snail-transduced B16-F10 melanoma (F10-snail+). We additionally found that Snail+ tumor cells frequently metastasize into bone marrow (BM) of the mice, and pluripotent CD45-ALCAM+ mesenchymal stem cells (MSCs) consequently increased in the mice. In this study, we attempted to characterize the Snail+ tumor-induced CD45-ALCAM+ MSCs (sMSCs). Results: The sMSCs were prepared by stimulating BMCs with F10-snail+ tumor supernatant for 5-7 days, or by sorting CD45-ALCAM+ cells from BM or spleen of the F10-snail+ tumor cells 2-3 weeks after implantation. When the mixture of the sMSCs and F10-mock tumor cells was subcutaneously injected in C57BL/6 mice, tumor growth was aggressively promoted, and spontaneous tumor dissemination in BM indicating de novo bone metastasis was observed, accompanied by increase of sMSCs in BM. In the tumor milieu and spleen of these mice, functionally impaired CD8(low) T cells and immunosuppressive Treg-inducible CD11b+Gr1+ MDSCs predominantly increased. Indeed, CD8(low) T cells were generated in the culture with splenic T cells and sMSCs, and MDSCs were expanded in the culture with BM cells and sMSCs. We identified key molecules responsible for the sMSC-induced events: ALCAM, ANGPT2 and FSTL1, which significantly increased only in the sMSC but not F10-mock-derived MSCs and normal MSCs. FSTL1 inhibited bone metastasis and consequent increase of sMSCs, CD8(low) T cells and MDSCs. Blocking ALCAM with mAb inhibited both sMSC expansion and CD8(low) T-cell induction. Blocking ANGPT2 inhibited expansion of MDSCs and Tregs rather than angiogenesis. Blocking FSTL1, which is a key trigger to initiate these cascades, in combination with elimination of other sMSC-associated factors significantly induced anti-tumor immune responses, resulting in complete inhibition of tumor growth and metastasis. Conclusions: These results suggest that sMSCs play a central role in the cancer EMT-induced immune dysfunction leading to tumor progression. Snail is reported to regulate acquisition of stem-like properties in tumor cells. However, how cancer stem cells would modulate the BM microenvironment and alter anti-tumor immune responses also remains unclear. Targeting sMSCs and its associated molecules may be a promising strategy for abrogating even cancer stem cells through reprogramming and activating anti-tumor immune responses appropriately. Citation Format: Chie Kudo-Saito, Takafumi Fuwa, Kouichi Murakami. Immune dysfunction cascades caused by ALCAM+ mesenchymal stem cells toward tumor progression. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 183. doi:10.1158/1538-7445.AM2014-183

P53MVA Therapy in Patients with Refractory Gastrointestinal Malignancies Elevates p53-Specific CD8+ T-cell Responses

To conduct a phase I trial of a modified vaccinia Ankara (MVA) vaccine delivering wild-type human p53 (p53MVA) in patients with refractory gastrointestinal cancers. Three patients were vaccinated with 1.0×10(8) plaque-forming unit (pfu) p53MVA followed by nine patients at 5.6×10(8) pfu. Toxicity was classified using the NCI Common Toxicity Criteria and clinical responses were assessed by CT scan. Peripheral blood samples were collected pre- and post-immunization for immunophenotyping, monitoring of p53MVA-induced immune response, and examination of PD1 checkpoint inhibition in vitro. p53MVA immunization was well tolerated at both doses, with no adverse events above grade 2. CD4+ and CD8+ T cells showing enhanced recognition of a p53 overlapping peptide library were detectable after the first immunization, particularly in the CD8+ T-cell compartment (P=0.03). However, in most patients, this did not expand further with the second and third immunization. The frequency of PD1+ T cells detectable in patients' peripheral blood mononuclear cells (PBMC) was significantly higher than in healthy controls. Furthermore, the frequency of PD1+ CD8+ T cells showed an inverse correlation with the peak CD8+ p53 response (P=0.02) and antibody blockade of PD1 in vitro increased the p53 immune responses detected after the second or third immunizations. Induction of strong T-cell and antibody responses to the MVA backbone were also apparent. p53MVA was well tolerated and induced robust CD8+ T-cell responses. Combination of p53MVA with immune checkpoint inhibition could help sustain immune responses and lead to enhanced clinical benefit.

T-cell Immune Suppression in Patients with Hematologic Malignancies: Clinical Implications

SUMMARY The reversion of immune suppression and restoration of T-cell function against leukemia remains a significant clinical challenge. However, the advent of improved antileukemia-specific T-cell induction and the generation of gene-modified T cells has extended cellular immunotherapy to hematological malignancies. Numerous immunotherapeutic protocols have been developed aiming to enhance antileukemia T-cell immune function, eliminate leukemic cells and prevent relapse. By contrast, abnormal expression of CTLA-4 and PD1/PD-L1 plays a critical role in effector T-cell responses and increases Treg suppressive activity in patients with tumors; therefore, blocking CTLA-4, PD1 and PD-L1 is a novel approach for immunotherapy.

A high fat soy oil diet enhances allergic symptoms while fish oil prevents allergic sensitization to cow's milk protein in mice via induction of regulatory T-cells

A high fat soy oil diet enhances allergic symptoms while fish oil prevents allergic sensitization to cow's milk protein in mice via induction of regulatory T-cells

DNGR-1 is dispensable for CD8+ T-cell priming during respiratory syncytial virus infection.

During respiratory syncytial virus (RSV) infection CD8(+) T cells both assist in viral clearance and contribute to immunopathology. CD8(+) T cells recognize viral peptides presented by dendritic cells (DCs), which can directly present viral antigens when infected or, alternatively, "cross-present" antigens after endocytosis of dead or dying infected cells. Mouse CD8α(+) and CD103(+) DCs excel at cross-presentation, in part because they express the receptor DNGR-1 that detects dead cells by binding to exposed F-actin and routes internalized cell debris into the cross-presentation pathway. As RSV causes death in infected epithelial cells, we tested whether cross-presentation via DNGR-1 is necessary for CD8(+) T-cell responses to the virus. DNGR-1-deficient or wild-type mice were intranasally inoculated with RSV and the magnitude of RSV-specific CD8(+) T-cell induction was measured. We found that during live RSV infection, cross-presentation via DNGR-1 did not have a major role in the generation of RSV-specific CD8(+) T-cell responses. However, after intranasal immunization with dead cells infected with RSV, a dependence on DNGR-1 for RSV-specific CD8(+) T-cell responses was observed, confirming the ascribed role of the receptor. Thus, direct presentation by DCs may be the major pathway initiating CD8(+) T-cell responses to RSV, while DNGR-1-dependent cross-presentation has no detectable role.

Prior to Foxp3⁺ regulatory T-cell induction, interleukin-10-producing B cells expand after Helicobacter pylori infection.

Regulatory T (Treg) cells play a critical role in Helicobacter pylori immune evasion and persistent infection. In addition to Treg cells, it is still unknown whether a newly defined B-cell subset, interleukin (IL)-10-producing B cells, is involved. Using a mouse model of H. pylori infection, we investigated the dynamic changes of IL-10-producing B cells and Foxp3(+) Treg cells in gastrointestinal mucosa, spleen and mesenteric lymph nodes following H. pylori infection. We observed that in addition to Foxp3(+) Treg cells, IL-10-producing B cells could also be induced after H. pylori infection and they expanded earlier than Foxp3(+) Treg cells did. Moreover, the regulatory immune responses induced by H. pylori were not limited to gastric mucosa. Our findings may provide new clues for further research on H. pylori immune evasion and diseases associated with H. pylori infection.