ADULT TETANUS, DIPHTHERIA, AND PERTUSSIS VACCINATION AND INCIDENT DEMENTIA

Adult vaccinations may reduce risk for dementia. We determined whether tetanus, diphtheria, pertussis (Tdap) vaccination is associated with lower risk for dementia. Analysis conducted with Veterans Health Affairs (VHA) administrative medical record data and replicated in private sector medical claims data. Patients were ≥65 years of age and free of dementia for 2 years prior to index date. Tdap vaccination in 2011 or 2012. Follow-up through 2018. Controls had no Tdap vaccination for the duration of follow-up. After controlling for confounding, patients with, compared to without Tdap vaccination, had a significantly lower risk for dementia in both cohorts (VHA: HR=0.58; 95%CI:0.54 - 0.63 and MarketScan: HR=0.58; 95%CI:0.48 - 0.70). Results were replicated in two cohorts with different clinical and sociodemographic characteristics. Several vaccine types are linked to decreased dementia risk, suggesting that these associations are due to nonspecific effects on inflammation rather than vaccine-induced pathogen-specific protective effects.

Mechanistic Investigation of Granzyme A inhibitory effects on intracellular Mycobacterium tuberculosis

One fourth of the world population is infected with Tuberculosis (TB). Our lab has identified γ9δ2 T cells that secrete Granzyme A (GzmA) with TB protective effects. In this study, we investigated the mechanism(s) by which human GzmA inhibits the intracellular replication of mycobacteria within infected human primary monocytes.

GzmA was added to mycobacteria-infected monocytes for downstream analyses using 2D-DIGE and shotgun proteomics. We generated WT, enzymatically inactive (S195A), and monomeric only (C93S) recombinant GzmA and performed: flow cytometry studies using viable mycobacteria; intracellular inhibition assays neutralizing CD14, TLR4 and TLR2; and GzmA immunoprecipitation experiments.

The 2D-DIGE proteomic analyses found the ER-stress response and ATP metabolism pathways as important for GzmA-mediated inhibition. Separately, shotgun proteomics uncovered the upregulation of Rab11FIP1 (important for phagocytosis). Both GzmA-WT and S195A proteins inhibited intracellular mycobacteria, but C93S did not. Neutralization of CD14 and TLR4, but not TLR2, reversed GzmA-inhibitory activity. GzmA-WT, S195A, and C93S all bound mycobacteria. However, GzmA-WT and S195A, but not GzmA-C93S, stably bound to TLR4 and CD14.

Collectively, these studies demonstrate key structural, functional, and inter-/intra-molecular features required for GzmA-mediated inhibition of intracellular mycobacteria including interactions between GzmA, mycobacteria, TLR4 and CD14. These interactions result in the ER stress response, altered ATP metabolism, enhanced phagocytosis, and inhibition of mycobacteria. Thus, GzmA’s potential role as opsonin could lead to novel host-directed therapeutics for TB infections.

Supported by grants from NIH (F30HL151136-01, R01AI048391-12)

Identification of adjuvants for γδ T cells in response to a novel M. tuberculosis vaccine antigen

γδ T cells are ideal effector cells against infectious diseases and cancer. They reside in blood, lymphoid organs, and mucosa, readily available for host defense. γδ T cells develop memory responses independent of MHC presentation. They perform immune functions such as cytolysis, cytokine production, antigen presentation, dendritic cell maturation, and promotion of B cell and T cell responses. Our lab reported that γδ T cells responsive to M. tuberculosis-specific 6-O-methylglucose-containing lipopolysaccharides (mGLP) inhibit intracellular mycobacterial growth. Preliminary data from NHP studies indicate that vaccination with mGLP and IL-2 greatly reduces Mtb burden post-challenge. IL-2 is not translatable for adjuvant use in humans. Therefore, novel adjuvants for γδ T cells are needed to develop optimal vaccine strategies. We are investigating adjuvant candidates to determine their ability to induce optimal activation and expansion of γδ T cells with mGLP or the phosphoantigen HMBPP. To screen adjuvants, PBMCs are incubated with antigen and adjuvant for 7 days, then analyzed for expansion of γδ T cells. Initially few adjuvants promoted γδ T cell expansion in response to HMBPP and none to mGLP. When matured monocyte-derived DCs were added, multiple adjuvants promoted γδ T cell expansion in response to HMBPP and mGLP stimulation without IL-2. We will determine mechanisms involved in novel adjuvant activity, whether adjuvant and mGLP-expanded γδ T cells inhibit intracellular mycobacterial growth, identify cytokines involved in candidate adjuvant effects, characterize cell surface markers upregulated on DC and γδ T cells, and test the best candidate adjuvant(s) with mGLP in NHP trials.

Supported by Gama Delta R01 AI048391

Thresholds versus Anomaly Detection for Surveillance of Pneumonia and Influenza Mortality

Computational surveillance of pneumonia and influenza mortality in the United States using FluView uses epidemic thresholds to identify high mortality rates but is limited by statistical issues such as seasonality and autocorrelation. We used time series anomaly detection to improve recognition of high mortality rates. Results suggest that anomaly detection can complement mortality reporting.

Transcriptomic and Metabolic Responses to a Live-Attenuated Francisella tularensis Vaccine

The immune response to live-attenuated Francisella tularensis vaccine and its host evasion mechanisms are incompletely understood. Using RNA-Seq and LC–MS on samples collected pre-vaccination and at days 1, 2, 7, and 14 post-vaccination, we identified differentially expressed genes in PBMCs, metabolites in serum, enriched pathways, and metabolites that correlated with T cell and B cell responses, or gene expression modules. While an early activation of interferon α/β signaling was observed, several innate immune signaling pathways including TLR, TNF, NF-κB, and NOD-like receptor signaling and key inflammatory cytokines such as Il-1α, Il-1β, and TNF typically activated following infection were suppressed. The NF-κB pathway was the most impacted and the likely route of attack. Plasma cells, immunoglobulin, and B cell signatures were evident by day 7. MHC I antigen presentation was more actively up-regulated first followed by MHC II which coincided with the emergence of humoral immune signatures. Metabolomics analysis showed that glycolysis and TCA cycle-related metabolites were perturbed including a decline in pyruvate. Correlation networks that provide hypotheses on the interplay between changes in innate immune, T cell, and B cell gene expression signatures and metabolites are provided. Results demonstrate the utility of transcriptomics and metabolomics for better understanding molecular mechanisms of vaccine response and potential host–pathogen interactions.

2492. Clinical, Virologic, and Immunologic Characteristics of Zika Virus Infection in a Cohort of US Patients

Background

The clinical, virologic and immunologic characteristics of Zika virus (ZIKV) infections in US patients are poorly defined.

Methods

US patients with suspected Zika virus (ZIKV) infection were enrolled and clinical data and specimens were prospectively collected. Body fluids were tested for ZIKV RNA by PCR and blood was tested using serologic and cellular immune assays. Findings from those with confirmed ZIKV infections (cases) and ZIKV-negative controls were compared.

Results

We enrolled 45 cases and 14 controls. The most commonly reported symptoms among cases and controls were maculopapular rash (97.8% and 81.8%), fatigue (86.7% and 81.8%) and arthralgia (82.2% and 54.5%), respectively. The sensitivity and duration of detection by PCR were highest in whole blood samples (94% of 35 cases who had samples collected up to day 79 post illness onset were positive); strikingly, 84% of those were still positive at 65–79 days post illness onset (Figure 1). ZIKV neutralizing antibodies were detected in all cases and none of the controls, and titers were significantly higher in dengue virus (DENV)-experienced subjects than in DENV-naïve ones (Figure 2). Among cases, anti-ZIKV IgG antibodies were also significantly higher in DENV-experienced patients, while anti-ZIKV IgM antibodies were no higher in DENV-experienced compared with naïve ones. Using intracellular cytokine staining, the highest frequencies of T cells producing IFN-γ, IL-2 and/or TNF-α were against the NS1, NS3, and NS5 proteins for CD4+ T cells, and against the E, NS3, and NS5 proteins for CD8+ T cells (Figure 3).

Conclusion

Detection of ZIKV RNA was more frequent and much more prolonged in whole blood samples compared with other body fluids. Diagnostic molecular assays on this easily obtained fluid should be prioritized for point-of-care development. Robust cellular responses to E, NS3 and NS5 proteins could have implications for vaccine development.

Disclosures

R. L. Atmar, Takeda Vaccines, Inc.: Investigator, Research grant.

Structural determinants in a glucose-containing lipopolysaccharide from Mycobacterium tuberculosis critical for inducing a subset of protective T cells

Mycobacteria synthesize intracellular, 6-O-methylglucose–containing lipopolysaccharides (mGLPs) proposed to modulate bacterial fatty acid metabolism. Recently, it has been shown that Mycobacterium tuberculosis mGLP specifically induces a specific subset of protective γ₉δ₂ T cells. Mild base treatment, which removes all the base-labile groups, reduces the specific activity of mGLP required for induction of these T cells, suggesting that acylation of the saccharide moieties is required for γ₉δ₂ T-cell activation. On the basis of this premise, we used analytical LC/MS and NMR methods to identify and locate the acyl functions on the mGLP saccharides. We found that mGLP is heterogeneous with respect to acyl functions and contains acetyl, isobutyryl, succinyl, and octanoyl groups and that all acylations in mGLP, except for succinyl and octanoyl residues, reside on the glucosyl residues immediately following the terminal 3-O-methylglucose. Our analyses also indicated that the octanoyl residue resides at position 2 of an internal glucose toward the reducing end. LC/MS analysis of the residual product obtained by digesting the mGLP with pancreatic α-amylase revealed that the product is an oligosaccharide terminated by α-(1→4)–linked 6-O-methyl-d-glucosyl residues. This oligosaccharide retained none of the acyl groups, except for the octanoyl group, and was unable to induce protective γ₉δ₂ T cells. This observation confirmed that mGLP induces γ₉δ₂ T cells and indicated that the acylated glucosyl residues at the nonreducing terminus of mGLP are required for this activity.

Peptide microarray-based characterization of antibody responses to host proteins after bacille Calmette-Guérin vaccination

BACKGROUND

Bacille Calmette-Guérin (BCG) is the world's most widely distributed vaccine, used against tuberculosis (TB), in cancer immunotherapy, and in autoimmune diseases due to its immunomodulatory properties. To date, the effect of BCG vaccination on antibody responses to host proteins has not been reported. High-content peptide microarrays (HCPM) offer a unique opportunity to gauge specific humoral immune responses.

METHODS

The sera of BCG-vaccinated healthy adults were tested on a human HCPM platform (4953 randomly selected epitopes of human proteins) to detect specific immunoglobulin gamma (IgG) responses. Samples were obtained at 56, 112, and 252 days after vaccination. Immunohistology was performed on lymph node tissue from patients with TB lymphadenitis. Results were analysed with a combination of existing and novel statistical methods.

RESULTS

IgG recognition of host peptides exhibited a peak at day 56 post BCG vaccination in all study subjects tested, which diminished over time. Primarily, IgG responses exhibited increased reactivity to ion transporters (sodium, calcium channels), cytokine receptors (interleukin 2 receptor β (IL2Rβ), fibroblast growth factor receptor 1 (FGFR1)), other cell surface receptors (inositol, somatostatin, angiopoeitin), ribonucleoprotein, and enzymes (tyrosine kinases, phospholipase) on day 56. There was decreased IgG reactivity to transforming growth factor-beta type 1 receptor (TGFβR1) and, in agreement with the peptide microarray findings, immunohistochemical analysis of TB-infected lymph node samples revealed an overexpression of TGFβR in granulomatous lesions. Moreover, the vesicular monoamine transporter (VMAT2) showed increased reactivity on days 112 and 252, but not on day 56 post-vaccination. IgG to interleukin 4 receptor (IL4R) showed increased reactivity at 112 days post-vaccination, while IgG to IL2Rβ and FGFR1 showed decreased reactivity on days 112 and 252 as compared to day 56 post BCG vaccination.

CONCLUSIONS

BCG vaccination modifies the host's immune landscape after 56 days, but this imprint changes over time. This may influence the establishment of immunological memory in BCG-vaccinated individuals.

A subset of protective γ9δ2 T cells is activated by novel mycobacterial antigens (MPF5P.740)

γ9δ2 T cells provide a natural bridge between innate and adaptive immunity and are prominently induced by both tuberculosis (TB) infection and bacillus Calmette Guérin (BCG) vaccination. Mycobacteria-expanded γ9δ2 T cells represent only a subset of the simple phosphoantigen (IPP and HMBPP)-responsive γ9δ2 T cells, this subset expresses a more oligoclonal set of TCR sequences, and only this subset efficiently recognizes and inhibits intracellular BCG/Mtb. We have been searching for new mycobacterial antigens capable of inducing the unique subset of γ9δ2 T cells that can recognize mycobacteria-infected macrophages and mediate protective effects inhibiting intracellular mycobacterial growth. We first ruled out protein, nucleic acid and apolar lipids with basic separations and enzymatic digestions. Acid hydrolysis, which digests complex carbohydrate structures, had the largest effect on eliminating Mtb fraction specific activity. Organic extractions resulted in sub-fractions with >100 fold enriched specific activity. A combination of MS, NMR, TLC indicate that methyl-glucose lipopolysaccharides (mGLP) are predominant components of the most active fractions. We are currently attempting to use synthetic techniques to confirm the specific activity of mGLP for induction of protective γ9δ2 T cells. These results have important implications for the development of new immunotherapeutic approaches for prevention/treatment of TB.

Antigen-specific MAIT cell subsets involved in TB immunity (INC2P.420)

Mucosal associated invariant T (MAIT) cells have a semi-invariant TCRVα chain, and depend on riboflavin metabolites (ribityllumazines, RLAg) produced by commensal flora and presented by the nonpolymorphic class Ib molecule MR1 for optimal development. We used MR1/RLAg tetramers and TCR Vα19 transgenic mice to study MR1-dependency, subset heterogeneity and protective effector functions important for tuberculosis (TB) immunity. We found that Vβ6/8+NK1.1+ MAIT cell subsets maximally expand peripherally in mice expressing MR1. In addition, we show that MR1/RLAg tetramer+ MAIT cells expressing CD4, CD8 or neither contain populations variably co-expressing Vβ6/8 and/or NK1.1, indicating that MAIT cells are more heterogeneous than previously thought. Furthermore, NK1.1 (NKR-P1C) is minimally expressed on mature Vβ6/8+ tetramer+ MAIT cells in the thymus but progressively increases with peripheral activation. Importantly, after virulent mycobacterial pulmonary infection, heterogeneous subsets of tetramer+ MAIT cells (CD4-CD8->CD4-CD8+>CD4+CD8-) co-expressing Vβ6/8 and NK1.1 and the homing molecules α4β1 and CXCR3, were recruited into the lungs and afforded maximal early protection in MR1-sufficient mice. Surprisingly, MAIT cells developing in the absence of MR1 were partially protective. Overall, we demonstrate diversity of MAIT cells, evidence that NK1.1 is an activation rather than developmental MAIT cell marker, and also that MAIT cells are important for TB protective immunity.

Effects of trans-sialidase enzyme activity, secretion and antigen persistence on the induction of protective immunity against Trypanosoma cruzi infection (VAC8P.1054)

Chagas Disease is a life-threatening illness caused by chronic infection with the Trypanosoma cruzi parasite. It affects up to 11 million people in Latin America, where it is a leading cause of heart disease, making vaccine development critical and worthwhile. Because the T. cruzi trans-sialidase (TS) enzyme is highly conserved and necessary for parasite virulence, it has strong potential as a vaccine target. We have shown that mice can be protected by vaccination with dendritic cells pulsed with a single pair of immunodominant TS epitopes, validating further exploration of TS as a target. We recently have generated live vaccines by transfecting Leishmania major with four TS variations: active secreted, active non-secreted, inactive secreted and inactive non-secreted. These also were transfected into an avirulent, dihydrofolate reductase knock-out strain of Leishmania to investigate the role of antigen persistence versus clearance on immune response. Mice will be infected with the recombinant Leishmania and later challenged with T. cruzi to analyze protective immunity. In preliminary experiments, recombinants were found to express the TS protein and immunizations protected BALB/c mice from infection. This project is the first examining the ability of recombinant Leishmania to serve as vaccine vehicles for Chagas Disease. These experiments will also elucidate the relative importance of inducing central and peripheral memory T cell populations for protective T. cruzi immunity.

Tetramer identification of functional mouse mucosal associated invariant T cells (INC6P.352)

Mucosal associated invariant T (MAIT) cells have a semi-invariant TCR Vα chain, and their development is dependent upon the commensal flora and the expression of MR1. MAIT cells are activated in vitro in an MR1-restricted manner by cells infected with diverse strains of bacteria suggesting a widely shared antigen. Such an antigen was recently defined by the observation that human MR1 binds bacterial riboflavin metabolites (ribityllumazines, RL antigens) that are capable of activating MAIT cells. Recently MR1/RL tetramers were constructed allowing us to compare MR1-dependency and function of mouse MAIT cell subsets in invariant TCR Vα19-Jα33 (Vα19i) transgenic (Tg) mice. Although significant numbers of tetramer+ cells were detected in both MR1+/+ and MR1-/- Vα19i Tg mice, only tetramer+ cells from MR1+/+ and not MR1-/- Vα19i Tg mice had predominant expression of CD69, NK1.1 and Vβ6/8 and displayed robust in vitro responses to IL-12+IL-18 or RL Ag. In addition, tetramer+ MAIT cells expressing CD4, CD8 or neither developing in MR1+/+ Vα19i Tg mice had disparate cytokine profiles in response to RL Ag. Most notably, after mycobacterial infection all MAIT cell subsets decreased in the blood regardless of whether they express NK1.1 and/or Vβ6/8; however, only the NK1.1+Vβ6/8+ subset predominated in the lung airways of infected MR1+/+ Vα19i Tg mice. These findings present evidence for the functional diversity of MAIT cell responses to innate cytokines, RL Ag and bacterial infection.

Targeting gammadelta regulatory T cell recruitment for breast cancer immunotherapy (TUM2P.904)

Immunosuppressive microenvironments induced by regulatory T cells (Treg) present a major barrier for successful anti-tumor immunotherapy. Understanding the mechanisms for the accumulation of different subtypes of Treg cells in the immunosuppressive tumor microenvironment is essential to improving cancer treatment. Enriched gammadelta1 T cell populations in tumor-infiltrating lymphocytes (TILs) suppress T cell responses and dendritic cell maturation in breast cancer, where their presence is correlated negatively with clinical outcomes. However, mechanism(s) that explain the increase in this class of gammadelta Treg cells in breast cancer patients have yet to be elucidated. In this study, we showed that IP-10 secreted by breast cancer cells attracted gammadelta Treg cells. Using neutralizing antibodies against chemokines secreted by breast cancer cells, we found that IP-10 was the only functional chemokine that causes gammadelta Treg cells to migrate toward breast cancer cells. In a humanized NSG mouse model, human breast cancer cells attracted gammadelta Treg cells as revealed by a live cell imaging system. IP-10 neutralization in vivo inhibited migration and trafficking of gammadelta Treg cells into breast tumor sites, enhancing tumor immunity mediated by tumor-specific T cells. Together, our studies show how gammadelta Treg cells accumulate in breast tumors, providing a rationale for their immunological targeting to relieve immunosuppression in the tumor microenvironment.

Comparison of the protective roles of Trypanosoma cruzi-specific Th1 and Th17 cells. (MPF6P.746)

Trypanosoma cruzi is the protozoan etiology of Chagas disease. T. cruzi-specific Th1 cells are known to be important for protective immunity, while the role of T. cruzi-specific Th17 cells has yet to be explored in detail. TCR-transgenic, T. cruzi-specific CD4+ T cells were differentiated in vitro into Th1 or Th17 cells and co-cultured with T. cruzi-infected peritoneal exudate macrophages. Protection was measured as inhibition of intracellular amastigote replication. In vivo, T. cruzi-specific Th1 or Th17 cells were adoptively transferred into Rag-/- mice along with naïve polyclonal CD8+ T cells. Mice were challenged with T. cruzi, persistent immune responses were measured, and protection was assessed by parasitemia and survival. In vitro, both Th1 and Th17 cells led to protection against intracellular T. cruzi growth in macrophages. Th1-mediated protection involved IFN-γ signaling and nitric oxide production by macrophages. In contrast, Th17-mediated protection was dependent on IL-17A but independent of iNOS induction. The role of reactive oxygen species, autophagy, apoptosis, and mechanisms of lysosomal killing are being studied. More importantly, Th17 cells were significantly more protective than Th1 cells in vivo, involving enhanced expansion of pathogen-specific CD8+ T cells. Thus, Th17 cells have both direct and indirect effects for T. cruzi protective immunity. Furthermore, we report the novel finding that Th17 cells provide important helper effects for CD8+ T cells.

A systems biology approach demonstrates that PO and ID BCG induce distinct CD4+ T cell molecular signatures. (VAC7P.970)

Vaccination with Bacillus Calmette-Guérin (BCG) is and constitutes the most widely used tuberculosis (TB) control strategy in the world. Protective efficacy of BCG may be affected by the methods and routes of vaccine administration. Here we have used a systems biology approach to study innate and adaptive responses to oral (PO) and intradermal (ID) BCG vaccination in humans. 60 healthy adults vaccinated with PO and/or ID BCG was studied. Although both PO and ID BCG could induce systemic Th1 responses capable of IFN-γ production, ID BCG more strongly induced systemic Th1 responses, while significantly higher mucosal responses (TB-specific sIgA and bronchoalveolar lavage T cells) were induced by PO BCG vaccination. In order to identify early gene signatures that predict optimal mucosal and systemic immune responses, CD4+ memory T cells were isolated from both PO and ID BCG vaccinated volunteers pre- (Day 0) and post-vaccination (Day 7 and 56), and studied by Illumina BeadArray transcriptomal analysis. Notably, distinct gene expression profiles were identified both on day 7 and day 56 comparing the PO and ID BCG vaccinated groups by GSEA analysis. Correlations between specific expression patterns and mucosal vs. systemic immune responses are being studied. These data highlight the utility of systems biology approaches in studying differential mucosal and systemic immune responses.

How MAIT cells control the growth of intracellular mycobacteria (P4381)

Mucosal associated invariant T cells or MAIT cells have a semi-invariant TCR Vα chain and limited Vβ chains. In addition MAIT cell development is dependent upon the commensal microbiota and the expression of MR1, a highly conserved class Ib molecule of mammals. Mouse and human MAIT cells are activated in an MR1-restricted manner by cells infected with diverse strains for bacteria suggesting a widely shared antigen. Remarkably, human MR1 was recently shown to bind select bacterial vitamin B metabolites capable of activating MAIT cells in an MR1-restricted manner. This finding raised the interesting question of the importance of MR1 presentation of vitamin B metabolites for controlling bacterial infection. To address this question we have developed a mouse model whereby mycobacteria infected macrophages are co-cultured with purified MAIT cells, and control of intracellular bacterial growth is monitored. Using this assay, MAIT cell control of mycobacterial growth was found to depend upon IL-12 secretion by infected macrophages and IFN-γ secretion by MAIT cells. Interestingly, in the absence of infection, MAIT cells secreted IFN-γ in response to recombinant IL-12 alone or antigenic vitamin B metabolites. These findings demonstrate that MAIT cells can be activated by either TCR or non-TCR interactions. The contribution of these two pathways of MAIT cell activation in the context of mycobacterial infection is currently being investigated.

Molecular control of human regulatory T cell suppression for tumor immunotherapy (P2106)

Immunotherapy is a promising approach for treating patients with malignant tumor, but immunosuppressive microenvironments induced by regulatory T cells (Tregs) present a major barrier to successful anti-tumor immunotherapy. A better understanding of the suppressive mechanisms utilized by Tregs is essential for the development of novel strategies to treat human cancer. Here we report that human Tregs can induce senescence in responder naïve and effector T cells in vitro and in vivo. Senescent responder T cells induced by human Tregs changed their phenotypes and cytokine profiles, and possessed potent suppressive function. Furthermore, Treg-mediated molecular control of senescence in responder T cells was associated with selective modulation of p38 and ERK1/2 signaling and cell cycle regulatory molecules p16, p21 and p53. We further revealed that human Treg-induced senescence and suppressor function could be blocked by TLR8 signaling and/or by specific ERK1/2 and p38 inhibition in vitro and in vivo in animal models. Our studies identify a novel mechanism of human Treg cell suppression that induces targeted responder T cell senescence, and provide new insights relevant for the development of strategies capable of preventing and/or reversing Treg-induced immune suppression for tumor immunotherapy.

The effects of Trypanosoma cruzi infection and vaccination on priming T. cruzi-specific CD4+ T cells. (P3346)

Trypanosoma cruzi is a protozoan parasite and the causative agent of Chagas disease. The T. cruzi protein trans-sialidase (TS) is currently under investigation as a vaccine candidate. There are defects in CD4+ T cell responses after T. cruzi infection as compared to TS vaccination. We sought to compare T cell receptor transgenic (Tg) TS-specific CD4+ T cell responses induced by infection versus vaccination through RNA microarrays. Tg TSaa57-74-specific CD4+ T cells were purified from naïve transgenic mice and activated in vitro by peptide-pulsed DCs or T. cruzi-infected and peptide-pulsed DCs, as well as in vivo by TS-DNA vaccination or T. cruzi infection. At various time points post activation, RNA was extracted from purified Tg CD4+ T cells and analyzed by microarray. In vitro, infection of DCs resulted in an increase in the expression of the signaling molecule Map3k10, the cytokine Il21, and factors involved in cell death/survival in CD4+ T cells. Following in vivo activation, proliferation was similar among Tg T cells stimulated with TS vaccination and T. cruzi infection. The microarray will reveal genes differentially expressed in response to T. cruzi infection with further analysis ongoing. These in vitro and in vivo studies using our transgenic T. cruzi-specific CD4+ T cells suggest that T. cruzi infection and TS vaccination differentially activate CD4+ T cells which may explain the defects in CD4+ T cells observed following T. cruzi infection.

Regulation of interleukin-27 production by Mycobacterium tuberculosis (110.2)

Mycobacterium tuberculosis (Mtb) remains a major global challenge to human healthcare and the mechanisms of how Mtb evades host immune surveillance to favor its survival are still largely unknown. In this study, we found that BCG and Mtb could activate IL-27 expression in human and mouse macrophages by induction of p28 subunit transcription. However, in parallel with these effects, BCG and Mtb stimulation of macrophages induces activation of p38 MAPK signaling molecules MLK3/MKK3/MK2 to prevent maximal IL-27 production. AP-1/c-Fos was shown to bind directly to the p28 promoter and induce p28 expression after Mtb stimulation. Overexpression of p38α inhibited the binding of c-Fos to the p28 promoter but had no effect on c-Fos protein expression or phosphorylation in response to Mtb. Furthermore, blockade of p38 by SB203580 enhanced Mtb-induced AP-1 binding to the p28 promoter. Importantly, we show that adding exogenous IL-27 to increase the levels produced by PBMCs stimulated with live mycobacteria enhances the ability of BCG-expanded T cells to inhibit intracellular mycobacterial growth in human macrophages. Taken together, our data demonstrate that mycobacterial stimulation induces both IL-27 production and p38 MAPK activation. Strategies designed to tip the balance toward positive regulation of p28 induction by mycobacteria could lead to enhanced protective TB immunity.

Human tumor-infiltrating Th17 cells have the capacity to differentiate into IFN-gamma+ and FOXP3+ T cells with potent suppressive function (66.27)

Accumulating evidence suggests that T-helper 17 (Th17) cells and regulatory T (Treg) cells may exhibit development plasticity, and that CD4+ Tregs can differentiate into IL-17-producing T cells; however, whether Th17 cells can reciprocally convert into Tregs has not been described. In this study, we generated Th17 clones from tumor-infiltrating T lymphocytes (TILs). We showed that Th17 clones generated from TILs can differentiate into IFN-gamma-producing and FOXP3+ cells after in vitro stimulation with OKT3 and allogeneic peripheral blood mononuclear cells (PBMCs). We further demonstrated that T-cell receptor (TCR) engagement was responsible for this conversion, and that this differentiation was due to the epigenetic modification and reprogramming of gene expression profiles, including lineage-specific transcriptional factor and cytokine genes. In addition to expressing IFN-gamma and FOXP3, we showed that these differentiated Th17 clones mediated potent suppressive function after repetitive stimulation with OKT3, suggesting that these Th17 clones had differentiated into functional Tregs. We further demonstrated that the Th17-derived Tregs, unlike naturally occurring CD4+CD25+ Tregs, did not reconvert back into Th17 cells even under Th17-biasing cytokine conditions. These results provide the critical evidence that human tumor-infiltrating Th17 cells can differentiate into Tregs and indicate a substantial developmental plasticity of Th17 cells.

Tumor microenvironments direct the recruitment and expansion of human Th17 cells (100.28)

Although Th17 cells play critical roles in the pathogenesis of many inflammatory and autoimmune diseases, their prevalence among tumor-infiltrating lymphocytes (TILs) and function in human tumor immunity remains largely unknown. We have recently demonstrated high percentages of Th17 cells in TILs from ovarian cancer patients, but the mechanisms of accumulation of these Th17 cells in the tumor microenvironment are still unclear. In this study, we further showed elevated Th17 cell populations in the TILs obtained from melanoma, breast and colon cancers, suggesting that development of tumor-infiltrating CD4+ Th17 cells may be a general feature in cancer patients. We then demonstrated that tumor microenvironmental RANTES and MCP-1 secreted by tumor cells and tumor-derived fibroblasts mediate the recruitment of Th17 cells. In addition, we found that tumor cells and tumor-derived fibroblasts produce a proinflammatory cytokine milieu as well as provide cell-to-cell contact engagement that facilitates the generation and expansion of Th17 cells. We also showed that inflammatory TLR and NOD2 signaling promote the attraction and generation of Th17 cells induced by tumor cells and tumor-derived fibroblasts. These results identify Th17 cells as an important component of human TILs, demonstrate mechanisms involved in the recruitment and regulation of Th17 cells in tumor microenvironments, and provide new insights relevant for the development of novel cancer immunotherapeutic approaches.

Recombinant bacillus Calmette-Guérin as a potential vector for preventive HIV type 1 vaccines

In August 1997, the World Health Organization (WHO) and the Joint United Nations Programme on HIV/AIDS (UNAIDS) convened an expert working group to discuss current strategies for the development of HIV type 1 vaccines. Based on the recent findings of investigators from Japan's National Institute of Infectious Diseases (NIID) in Tokyo using recombinant bacillus Calmette-Guérin (rBCG) as a potential vectored vaccine for HIV, a recommendation was made that further work in this area is a priority. As a result, the working group reconvened in September 1998 to discuss the progress to date with this vaccine approach, as well as areas of related research to assess the feasibility of a BCG-vectored HIV vaccine. This report summarizes the discussions addressing the available scientific data on the potential use of rBCG as a vector for preventive HIV vaccines, the work necessary to move such candidate vaccines into Phase 1 clinical trials, and recommendations targeted at facilitating the long-term development of rBCG-vectored HIV vaccines.

Immune responses to plasmid DNA encoding the hepatitis C virus core protein

Hepatitis C virus (HCV) is a major causative agent of parenterally transmitted non-A, non-B hepatitis. The genomic region encoding the virion-associated core protein is relatively conserved among HCV strains. To generate a DNA vaccine capable of expressing the HCV core protein, the genomic region encoding amino acid residues 1 to 191 of the HCV-1 strain was amplified and cloned into an eukaryotic expression vector. Intramuscular inoculation of recombinant plasmid DNA into BALB/c mice (H-2d) generated core-specific antibody responses, lymphoproliferative responses, and cytotoxic T-lymphocyte activity. Our results suggest that the HCV core polynucleotide warrants further investigation as a potential vaccine against HCV infection.