Pathogen-Specific T Cell Polyfunctionality Is a Correlate of T Cell Efficacy and Immune Protection

Polyfunctional HIV-1 specific response by CD8+ T lymphocytes expressing high levels of CD300a

CD300a receptor is found on different CD8+ T cell subsets and its expression has been associated to a more cytotoxic molecular signature. CD300a has an important role in some viral infections and its expression levels are known to be modulated by human immunodeficiency virus (HIV)−1 infection on several cell types. The main objective of this work was to investigate CD300a expression and its regulation during HIV-1 specific CD8+ T cell responses. CD300a receptor expression was analysed by multiparametric flow cytometry on CD8+ T lymphocytes from HIV negative donors, naive HIV-1+ individuals and HIV-1+ subjects under suppressive combined antiretroviral therapy (cART). HIV-1 specific CD8+ T cell response was studied by stimulating cells with HIV-1 derived peptides or with a Gag HIV-1 peptide. Our results showed that HIV-1 specific CD8+ T cells expressing higher levels of CD300a were more polyfunctional showing an increased degranulation and cytokine production. Moreover, we observed an up-regulation of CD300a expression after Gag HIV-1 peptide stimulation. Finally, our results demonstrated an inverse correlation between CD300a expression on CD8+ T lymphocytes and HIV disease progression markers. In conclusion, CD300a expression is associated to a better and more polyfunctional HIV-1 specific CD8+ T cell response.

Effect of Different Adjuvants on the Longevity and Strength of Humoral and Cellular Immune Responses to the HCV Envelope Glycoproteins

Infection by Hepatitis C virus (HCV) can lead to liver cirrhosis/hepatocellular carcinoma and remains a major cause of serious disease morbidity and mortality worldwide. However, current treatment regimens remain inaccessible to most patients, particularly in developing countries, and, therefore, the development of a novel vaccine capable of protecting subjects from chronic infection by HCV could greatly reduce the rates of HCV infection, subsequent liver pathogenesis, and in some cases death. Herein, we evaluated two different semi-synthetic archaeosome formulations as an adjuvant to the E1/E2 HCV envelope protein in a murine model and compared antigen-specific humoral (levels of anti-E1/E2 IgG and HCV pseudoparticle neutralization) and cellular responses (numbers of antigen-specific cytokine-producing T cells) to those generated with adjuvant formulations composed of mimetics of commercial adjuvants including a squalene oil-in-water emulsion, aluminum hydroxide/monophosphoryl lipid A (MPLA) and liposome/MPLA/QS-21. In addition, we measured the longevity of these responses, tracking humoral, and cellular responses up to 6 months following vaccination. Overall, we show that the strength and longevity of anti-HCV responses can be influenced by adjuvant selection. In particular, a simple admixed sulfated S-lactosylarchaeol (SLA) archaeosome formulation generated strong levels of HCV neutralizing antibodies and polyfunctional antigen-specific CD4 T cells producing multiple cytokines such as IFN-γ, TNF-α, and IL-2. While liposome/MPLA/QS-21 as adjuvant generated superior cellular responses, the SLA E1/E2 admixed formulation was superior or equivalent to the other tested formulations in all immune parameters tested.

Kopycinski J, Gilmour J, Kumar S, Muthu M, Subramaniam S, Swaminathan S, Prasad Tripathy S, Luke HE. Induction and maintenance of bi-functional (IFN-γ + IL-2+ and IL-2+ TNF-α+) T cell responses by DNA prime MVA boosted subtype C prophylactic vaccine tested in a Phase I trial in India

Effective vaccine design relies on accurate knowledge of protection against a pathogen, so as to be able to induce relevant and effective protective responses against it. An ideal Human Immunodeficiency virus (HIV) vaccine should induce humoral as well as cellular immune responses to prevent initial infection of host cells or limit early events of viral dissemination. A Phase I HIV-1 prophylactic vaccine trial sponsored by the International AIDS Vaccine Initiative (IAVI) was conducted in India in 2009.The trial tested a HIV-1 subtype C vaccine in a prime-boost regimen, comprising of a DNA prime (ADVAX) and Modified Vaccine Ankara (MVA) (TBC-M4) boost. The trial reported that the vaccine regimen was safe, well tolerated, and resulted in enhancement of HIV-specific immune responses. However, preliminary immunological studies were limited to vaccine-induced IFN-γ responses against the Env and Gag peptides. The present study is a retrospective study to characterize in detail the nature of the vaccine-induced cell mediated immune responses among volunteers, using Peripheral Blood Mononuclear Cells (PBMC) that were archived during the trial. ELISpot was used to measure IFN-γ responses and polyfunctional T cells were analyzed by intracellular multicolor flow cytometry. It was observed that DNA priming and MVA boosting induced Env and Gag specific bi-functional and multi-functional CD4⁺ and CD8⁺ T cells expressing IFN-γ, TNF-α and IL-2. The heterologous prime-boost regimen appeared to be slightly superior to the homologous prime-boost regimen in inducing favorable cell mediated immune responses. These results suggest that an in-depth analysis of vaccine-induced cellular immune response can aid in the identification of correlates of an effective immunogenic response, and inform future design of HIV vaccines.

Association of synovial tissue polyfunctional T-cells with DAPSA in psoriatic arthritis

OBJECTIVE

This study examines polyfunctional T-cells in psoriatic arthritis (PsA) synovial tissue and their associations with clinical disease and implications for therapy.

METHODS

PsA synovial tissue was enzymatically/mechanically digested to generate synovial tissue single cell suspensions. Frequencies of polyfunctional CD4, CD8, T-helper 1 (Th1), Th17 and exTh17 cells, using CD161 as a marker of Th17 plasticity, were determined by flow cytometry in matched PsA synovial tissue and peripheral blood. Synovial T-cell polyfunctionality was assessed in relation to Disease Activity in PSoriatic Arthritis (DAPSA) and in synovial cell suspensions cultured with a current mode of treatment, phosphodiesterase 4 (PDE4) inhibitor.

RESULTS

PsA synovial tissue infiltrating CD4⁺ T-cells expressed higher levels of interleukin (IL)-17A, interferon gamma (IFN-γ), GM-CSF and CD161, with parallel enrichment of Th1, Th17 and exTh17 T-helper subsets (all p<0.05). Interestingly, a significant proportion of synovial T-cell subsets were triple-positive for GM-CSF, tumour necrosis factor (-TNF), -IL-17 or IFN-γ compared with matched blood (all p<0.05). Importantly, frequencies of polyfunctional T-cells correlated with DAPSA: Th1-GM-CSF⁺/TNF⁺/IFN-γ⁺ (r=0.7, p<0.01), Th17-GM-CSF⁺/TNF⁺/IL-17⁺ (r=0.6, p<0.057) and exTh17-GM-CSF⁺/TNF⁺/IFN-γ⁺ (r=0.7, p=0.0096), with no associations observed for single cytokine-producing T-cells. Following ex vivo culture of PsA synovial tissue cell suspensions, polyfunctional GM-CSF⁺TNFα⁺IL-17A⁺ or/IFN-γ⁺-producing T-cells (p<0.05), but not single cytokine-producing T-cells, were inhibited with a PDE4 inhibitor.

CONCLUSION

These data demonstrate enrichment of polyfunctional T-cells in PsA synovial tissue which were strongly associated with DAPSA and ex vivo therapeutic response.

An Ad/MVA vectored Theileria parva antigen induces schizont-specific CD8+ central memory T cells and confers partial protection against a lethal challenge

The parasite Theileria parva is the causative agent of East Coast fever (ECF), one of the most serious cattle diseases in sub-Saharan Africa, and directly impacts smallholder farmers’ livelihoods. There is an efficient live-parasite vaccine, but issues with transmission of vaccine strains, need of a cold chain, and antibiotics limit its utilization. This has fostered research towards subunit vaccination. Cytotoxic T lymphocytes (CTL) are crucial in combating the infection by lysing T. parva-infected cells. Tp1 is an immunodominant CTL antigen, which induces Tp1-specific responses in 70–80% of cattle of the A18 or A18v haplotype during vaccination with the live vaccine. In this study, human adenovirus serotype 5 (HAd5) and modified vaccinia Ankara (MVA) were assessed for their ability to induce Tp1-specific immunity. Both viral vectors expressing the Tp1 antigen were inoculated in cattle by a heterologous prime-boost vaccination regimen. All 15 animals responded to Tp1 as determined by ELISpot. Of these, 14 reacted to the known Tp1 epitope, assayed by ELISpot and tetramer analyses, with CTL peaking 1-week post-MVA boost. Eleven animals developed CTL with specific cytotoxic activity towards peripheral blood mononuclear cells (PBMC) pulsed with the Tp1 epitope. Moreover, 36% of the animals with a Tp1 epitope-specific response survived a lethal challenge with T. parva 5 weeks post-MVA boost. Reduction of the parasitemia correlated with increased percentages of central memory lymphocytes in the Tp1 epitope-specific CD8⁺ populations. These results indicate that Tp1 is a promising antigen to include in a subunit vaccine and central memory cells are crucial for clearing the parasite.

A vaccine expressing parasitic proteins offers more convenient East Coast fever prophylaxis. Current vaccination for the cattle disease, caused by the parasite Theileria parva and a detriment to sub-Saharan African farmers, involves inconvenient injection with live parasites before antibiotic treatment (ITM). A collaboration led by Nicholas Svitek, of the Kenyan International Livestock Research Institute, designed a candidate to provoke cellular immune responses against the parasitic antigen Tp1—an ITM vaccine candidate. In tests on cattle, 93% created Tp1-targeting T cells, and 33% survived a lethal dose of T. parva. The East Coast fever reduction seen in animals in this research outperformed a recent study and was able to generate the same immune memory cells that ITM inspires to provide long-lasting protection. Future research might integrate more antigens with this Tp1 vaccine to provide more comprehensive protection.

Novel Plasmodium antigens identified via genome-based antibody screen induce protection associated with polyfunctional T cell responses

The development of vaccines against complex intracellular pathogens, such as Plasmodium spp., where protection is likely mediated by cellular immune responses, has proven elusive. The availability of whole genome, proteome and transcriptome data has the potential to advance rational vaccine development but yet there are no licensed vaccines against malaria based on antigens identified from genomic data. Here, we show that the Plasmodium yoelii orthologs of four Plasmodium falciparum proteins identified by an antibody-based genome-wide screening strategy induce a high degree of sterile infection-blocking protection against sporozoite challenge in a stringent rodent malaria model. Protection increased in multi-antigen formulations. Importantly, protection was highly correlated with the induction of multifunctional triple-positive T cells expressing high amounts of IFN-γ, IL-2 and TNF. These data demonstrate that antigens identified by serological screening are targets of multifunctional cellular immune responses that correlate with protection. Our results provide experimental validation for the concept of rational vaccine design from genomic sequence data.

A Chlamydia-Specific TCR-Transgenic Mouse Demonstrates Th1 Polyfunctionality with Enhanced Effector Function

Chlamydia is responsible for millions of new infections annually, and current efforts focus on understanding cellular immunity for targeted vaccine development. The Chlamydia-specific CD4 T cell response is characterized by the production of IFN-γ, and polyfunctional Th1 responses are associated with enhanced protection. A major limitation in studying these responses is the paucity of tools available for detection, quantification, and characterization of polyfunctional Ag-specific T cells. We addressed this problem by developing a TCR-transgenic (Tg) mouse with CD4 T cells that respond to a common Ag in Chlamydia muridarum and Chlamydia trachomatis Using an adoptive-transfer approach, we show that naive Tg CD4 T cells become activated, proliferate, migrate to the infected tissue, and acquire a polyfunctional Th1 phenotype in infected mice. Polyfunctional Tg Th1 effectors demonstrated enhanced IFN-γ production compared with polyclonal cells, protected immune-deficient mice against lethality, mediated bacterial clearance, and orchestrated an anamnestic response. Adoptive transfer of Chlamydia-specific CD4 TCR-Tg T cells with polyfunctional capacity offers a powerful approach for analysis of protective effector and memory responses against chlamydial infection and demonstrates that an effective monoclonal CD4 T cell response may successfully guide subunit vaccination strategies.

Enrichment of IL-17A+ IFN-γ+ and IL-22+ IFN-γ+ T cell subsets is associated with reduction of NKp44+ ILC3s in the terminal ileum of Crohn's disease patients

Crohn's disease (CD) is a chronic inflammatory condition of the human gastrointestinal tract whose aetiology remains largely unknown. Dysregulated adaptive immune responses and defective innate immunity both contribute to this process. In this study, we demonstrated that the interleukin (IL)-17A+ interferon (IFN)-γ+ and IL-22+ IFN-γ+ T cell subsets accumulated specifically in the inflamed terminal ileum of CD patients. These cells had higher expression of Ki-67 and were active cytokine producers. In addition, their proportions within both the IL-17A-producer and IL-22-producer populations were increased significantly. These data suggest that IL-17A+ IFN-γ+ and IL-22+ IFN-γ+ T cell subsets might represent the pathogenic T helper type 17 (Th17) population in the context of intestinal inflammation for CD patients. In the innate immunity compartment we detected a dramatic alteration of both phenotype and function of the intestinal innate lymphoid cells (ILCs), that play an important role in the maintenance of mucosal homeostasis. In the inflamed gut the frequency of the NKp44- CD117- ILC1s subset was increased significantly, while the frequency of NKp44+ ILC3s was reduced. Furthermore, the frequency of human leucocyte antigen D-related (HLA-DR)-expressing-NKp44+ ILC3s was also reduced significantly. Interestingly, the decrease in the NKp44+ ILC3s population was associated with an increase of pathogenic IL-17A+ IFN-γ+ and IL-22+ IFN-γ+ T cell subsets in the adaptive compartment. This might suggest a potential link between NKp44+ ILC3s and the IL-17A+ IFN-γ+ and IL-22+ IFN-γ+ T cell subsets in the terminal ileum of CD patients.

A constant companion: immune recognition and response to cytomegalovirus with aging and implications for immune fitness

Approximately 50% of individuals aged 6-49 years in the United States are infected with cytomegalovirus (CMV), with seroprevalence increasing with age, reaching 85-90% by 75-80 years according to Bate et al. (Clin Infect Dis 50 (11): 1439-1447, 2010) and Pawelec et al. (Curr Opin Immunol 24:507-511, 2012). Following primary infection, CMV establishes lifelong latency with periodic reactivation. Immunocompetent hosts experience largely asymptomatic infection, but CMV can cause serious illness in immunocompromised populations, such as transplant patients and the elderly. Control of CMV requires constant immune surveillance, and recent discoveries suggest this demand alters general features of the immune system in infected individuals. Here, we review recent advances in the understanding of the immune response to CMV and the role of CMV in immune aging and fitness, while highlighting the importance of potential confounding factors that influence CMV studies. Understanding how CMV contributes to shaping "baseline" immunity has important implications for a host's ability to mount effective responses to diverse infections and vaccination.

A third generation vaccine for human visceral leishmaniasis and post kala azar dermal leishmaniasis: First-in-human trial of ChAd63-KH

BACKGROUND

Visceral leishmaniasis (VL or kala azar) is the most serious form of human leishmaniasis, responsible for over 20,000 deaths annually, and post kala azar dermal leishmaniasis (PKDL) is a stigmatizing skin condition that often occurs in patients after successful treatment for VL. Lack of effective or appropriately targeted cell mediated immunity, including CD8+ T cell responses, underlies the progression of VL and progression to PKDL, and can limit the therapeutic efficacy of anti-leishmanial drugs. Hence, in addition to the need for prophylactic vaccines against leishmaniasis, the development of therapeutic vaccines for use alone or in combined immuno-chemotherapy has been identified as an unmet clinical need. Here, we report the first clinical trial of a third-generation leishmaniasis vaccine, developed intentionally to induce Leishmania-specific CD8+ T cells.

METHODS

We conducted a first-in-human dose escalation Phase I trial in 20 healthy volunteers to assess the safety, tolerability and immunogenicity of a prime-only adenoviral vaccine for human VL and PKDL. ChAd63-KH is a replication defective simian adenovirus expressing a novel synthetic gene (KH) encoding two Leishmania proteins KMP-11 and HASPB. Uniquely, the latter was engineered to reflect repeat domain polymorphisms and arrangements identified from clinical isolates. We monitored innate immune responses by whole blood RNA-Seq and antigen specific CD8+ T cell responses by IFNγ ELISPOT and intracellular flow cytometry.

FINDINGS

ChAd63-KH was safe at intramuscular doses of 1x1010 and 7.5x1010 vp. Whole blood transcriptomic profiling indicated that ChAd63-KH induced innate immune responses characterized by an interferon signature and the presence of activated dendritic cells. Broad and quantitatively robust CD8+ T cell responses were induced by vaccination in 100% (20/20) of vaccinated subjects.

CONCLUSION

The results of this study support the further development of ChAd63-KH as a novel third generation vaccine for VL and PKDL.

TRIAL REGISTRATION

This clinical trial (LEISH1) was registered at EudraCT (2012-005596-14) and ISRCTN (07766359).

Polyfunctional and IFN- monofunctional human CD4+ T cell populations are molecularly distinct

Pathogen-specific polyfunctional T cell responses have been associated with favorable clinical outcomes, but it is not known whether molecular differences exist between polyfunctional and monofunctional cytokine-producing T cells. Here, we report that polyfunctional CD4⁺ T cells induced during Plasmodiumfalciparum (P. falciparum) blood-stage infection in humans have a unique transcriptomic profile compared with IFN-γ monofunctional CD4⁺ T cells and, thus, are molecularly distinct. The 14-gene signature revealed in P. falciparum-reactive polyfunctional T cells is associated with cytokine signaling and lymphocyte chemotaxis, and systems biology analysis identified IL-27 as an upstream regulator of the polyfunctional gene signature. Importantly, the polyfunctional gene signature is largely conserved in Influenza-reactive polyfunctional CD4⁺ T cells, suggesting that polyfunctional T cells have core characteristics independent of pathogen specificity. This study provides the first evidence to our knowledge that consistent molecular differences exist between polyfunctional and monofunctional CD4⁺ T cells.

Selective expansion of high functional avidity memory CD8 T cell clonotypes during hepatitis C virus reinfection and clearance

The dynamics of the memory CD8 T cell receptor (TCR) repertoire upon virus re-exposure and factors governing the selection of TCR clonotypes conferring protective immunity in real life settings are poorly understood. Here, we examined the dynamics and functionality of the virus-specific memory CD8 TCR repertoire before, during and after hepatitis C virus (HCV) reinfection in patients who spontaneously resolved two consecutive infections (SR/SR) and patients who resolved a primary but failed to clear a subsequent infection (SR/CI). The TCR repertoire was narrower prior to reinfection in the SR/SR group as compared to the SR/CI group and became more focused upon reinfection. CD8 T cell clonotypes expanding upon re-exposure and associated with protection from viral persistence were recruited from the memory T cell pool. Individual CD8 T cell lines generated from the SR/SR group exhibited higher functional avidity and polyfunctionality as compared to cell lines from the SR/CI group. Our results suggest that protection from viral persistence upon HCV reinfection is associated with focusing of the HCV-specific CD8 memory T cell repertoire from which established cell lines showed high functional avidity. These findings are applicable to vaccination strategies aiming at shaping the protective human T cell repertoire.

In this study we examined the diversity and dynamics of the repertoire of receptors of CD8 T cells that are selected and enriched upon real-life multiple exposures to viral infections. Using hepatitis C virus (HCV) infection in a cohort of high risk people who inject drugs, we demonstrate that protection upon two subsequent infections was associated with a narrow repertoire of virus-specific CD8 T cells and selective expansion of cells with high polyfunctionality (increased TNFα production and cytotoxic potential). Our results have important implications in vaccination programs aiming at shaping the CD8 T cell repertoire against viral infections and cancers.

Mechanisms Underlying T Cell Immunosenescence: Aging and Cytomegalovirus Infection

The ability of the human immune system to protect against infectious disease declines with age and efficacy of vaccination reduces significantly in the elderly. Aging of the immune system, also termed as immunosenescence, involves many changes in human T cell immunity that is characterized by a loss in naïve T cell population and an increase in highly differentiated CD28- memory T cell subset. There is extensive data showing that latent persistent human cytomegalovirus (HCMV) infection is also associated with age-related immune dysfunction in the T cells, which might enhance immunosenescence. Understanding the molecular mechanisms underlying age-related and HCMV-related immunosenescence is critical for the development of effective age-targeted vaccines and immunotherapies. In this review, we will address the role of both aging and HCMV infection that contribute to the T cell senescence and discuss the potential molecular mechanisms in aged T cells.

Polyfunctional HIV-specific T cells in Post-Treatment Controllers

To further understand the exceptional HIV-1 control observed in Post-Treatment Controllers (PTCs) from the Virological and Immunological Sustained CONtrol after Treatment Interruption study we investigated their HIV-specific T-cell responses. Polyfunctionality of HIV-specific CD4 and CD8 T cells and the ratios of HIV-specific CD4 T cells per infected cells were similar in post-treatment controllers, continuously early-treated patients and long-term non-progressors Overall early treatment appears to preserve robust HIV-specific CD4 T cells, which might contribute to the posttreatment control of HIV.

Immune responses elicited by the GEN-003 candidate HSV-2 therapeutic vaccine in a randomized controlled dose-ranging phase 1/2a trial

PURPOSE

GEN-003 is a candidate therapeutic HSV-2 vaccine containing a fragment of infected cell protein 4 (ICP4.2), a deletion mutant of glycoprotein D2 (gD2ΔTMR), and Matrix-M2 adjuvant. In a dose-ranging phase 1/2a clinical trial, immunization with GEN-003 reduced viral shedding and the percentage of reported herpetic lesion days. Here we examine the immune responses in the same trial, to characterize vaccine-related changes in antibody and cell-mediated immunity.

METHODS

Participants with genital HSV-2 infection were randomized to 1 of 3 doses of GEN-003, antigens without adjuvant, or placebo. Subjects received 3 intramuscular doses, three weeks apart, and were monitored for viral shedding, lesions and immunogenicity. Antibody titers were measured by ELISA and neutralization assay in serum samples collected at baseline and 3weeks post each dose. T cell responses were assessed pre-immunization and 1week post each dose by IFN-γ ELISpot and intracellular cytokine staining. Blood was also collected at 6 and 12months to monitor durability of immune responses.

RESULTS

Antibody and T cell responses increased with vaccination and were potentiated by adjuvant. Among the doses tested, the rank order of reduction in viral shedding follows the ranking of fold change from baseline in T cell responses. Some immune responses persisted up to 12months.

CONCLUSION

All measures of immunity are increased by vaccination with GEN-003; however, a correlate of protection is yet to be defined.

Functional Diversity of Cytomegalovirus-Specific T Cells Is Maintained in Older People and Significantly Associated With Protein Specificity and Response Size

Background. Parallel upregulation of several T-cell effector functions (ie, polyfunctionality) is believed to be critical for the protection against viruses but thought to decrease in large T-cell expansions, in particular at older ages. The factors determining T-cell polyfunctionality are incompletely understood. Here we revisit the question of cytomegalovirus (CMV)–specific T-cell polyfunctionality, including a wide range of T-cell target proteins, response sizes, and participant ages.

Methods. Polychromatic flow cytometry was used to analyze the functional diversity (ie, CD107, CD154, interleukin 2, tumor necrosis factor, and interferon γ expression) of CD4⁺ and CD8⁺ T-cell responses to 19 CMV proteins in a large group of young and older United Kingdom participants. A group of oldest old people (age >85 years) was included to explore these parameters in exceptional survivors. Polyfunctionality was assessed for each protein-specific response subset, by subset and in aggregate, across all proteins by using the novel polyfunctionality index.

Results. Polyfunctionality was not reduced in healthy older people as compared to young people. However, it was significantly related to target protein specificity. For each protein, it increased with response size. In the oldest old group, overall T-cell polyfunctionality was significantly lower.

Discussion. Our results give a new perspective on T-cell polyfunctionality and raise the question of whether maintaining polyfunctionality of CMV-specific T cells at older ages is necessarily beneficial.

HIV-specific Th2 and Th17 responses predict HIV vaccine protection efficacy

Understanding the factors that delineate the efficacy of T-cell responses towards pathogens is crucial for our ability to develop potent therapies and vaccines against infectious diseases, such as HIV. Here we show that a recently developed analytical tool, the polyfunctionality index (PI), not only enables prediction of protection after vaccination against HIV, but also allows identification of the immunological pathways involved. Our data suggest that induction of a synergistic network of CD4(+) T-cell subsets is implicated in HIV-protection. Accordingly, we provide evidence that vaccine-induced protection is associated with CD40L expressing Th2 cells and IL-2 secreting Th17 cells. In conclusion, we describe a novel approach that is widely applicable and readily interpretable in a biological and clinical context. This approach could greatly impact our fundamental understanding of T-cell immunity as well as the search for effective vaccines.

IL-7 signaling imparts polyfunctionality and stemness potential to CD4(+) T cells

The functional status of CD4(+) T cells is a critical determinant of antitumor immunity. Polyfunctional CD4(+) T cells possess the ability to concomitantly produce multiple Th1-type cytokines, exhibiting a functional attribute desirable for cancer immunotherapy. However, the mechanisms by which these cells are induced are neither defined nor it is clear if these cells can be used therapeutically to treat cancer. Here, we report that CD4(+) T cells exposed to exogenous IL-7 during antigenic stimulation can acquire a polyfunctional phenotype, characterized by their ability to simultaneously express IFNγ, IL-2, TNFα and granzyme B. This IL-7-driven polyfunctional phenotype was associated with increased histone acetylation in the promoters of the effector genes, indicative of increased chromatin accessibility. Moreover, forced expression of a constitutively active (CA) form of STAT5 recapitulated IL-7 in inducing CD4(+) T-cell polyfunctionality. Conversely, the expression of a dominant negative (DN) form of STAT5 abolished the ability of IL-7 to induce polyfunctional CD4(+) T cells. These in-vitro-generated polyfunctional CD4(+) T cells can traffic to tumor and expand intratumorally in response to immunization. Importantly, adoptive transfer of polyfunctional CD4(+) T cells following lymphodepletive chemotherapy was able to eradicate large established tumors. This beneficial outcome was associated with the occurrence of antigen epitope spreading, activation of the endogenous CD8(+) T cells and persistence of donor CD4(+) T cells exhibiting memory stem cell attributes. These findings indicate that IL-7 signaling can impart polyfunctionality and stemness potential to CD4(+) T cells, revealing a previously unknown property of IL-7 that can be exploited in adoptive T-cell immunotherapy.

The Antitumor Efficacy of IL2/IL21-Cultured Polyfunctional Neu-Specific T Cells Is TNFα/IL17 Dependent

PURPOSE

Infusion of HER2-specific T cells, derived from vaccine-primed patients and expanded with IL2/IL12, has induced tumor regression in a minority of patients with metastatic treatment-refractory HER2(+) breast cancer. We questioned whether alteration of cytokine growth factors used to culture vaccine-primed T cells could improve antitumor activity.

EXPERIMENTAL DESIGN

Using the TgMMTV-neu murine mammary tumor model, we cultured T cells derived from mice immunized with a previously defined neu class II peptide, p98-114 (neu p98), and evaluated different cytokine combinations for expansion.

RESULTS

Infusion of neu p98-specific T-cell lines derived from all cytokine conditions evaluated resulted in significant antitumor activity compared with infused naïve splenocytes (P < 0.05). T cells cultured with IL2/IL21 could uniquely mediate complete regression of spontaneous mammary tumors. IL2/IL21 cultured neu-specific T cells demonstrated a different cytokine secretion pattern as compared with other cultured T cells; secreting high levels of TNFα and IL17 (P < 0.05). Moreover, tumor-infiltrating CD8(+) cells were significantly increased after the infusion of IL2/IL21 cultured T cells as compared with tumors treated with T cells expanded under other cytokine conditions (P < 0.001). The antitumor effect of the infusion of IL2/IL21 cultured cells was mediated by CD8 T cells. Depletion of TNFα or IL17, but not IFNγ, abrogated the tumor growth inhibition induced by the IL2/IL21 T cells and markedly decreased the influx of CD8 into tumors. Finally, IL2/IL21-cultured human antigen specific T cells also displayed a similar polyfunctional Th1/Th17 phenotype.

CONCLUSIONS

Expansion of HER2 vaccine-primed T cells with IL2/IL21 may have the potential to effectively mediate tumor regression when used in adoptive transfer. Clin Cancer Res; 22(9); 2207-16. ©2015 AACR.