LuAnn Thompson-Snipes

Functional Specializations of Human Epidermal Langerhans Cells and CD14+ Dermal Dendritic Cells

Little is known about the functional differences between the human skin myeloid dendritic cell (DC) subsets, epidermal CD207(+) Langerhans cells (LCs) and dermal CD14(+) DCs. We showed that CD14(+) DCs primed CD4(+) T cells into cells that induce naive B cells to switch isotype and become plasma cells. In contrast, LCs preferentially induced the differentiation of CD4(+) T cells secreting T helper 2 (Th2) cell cytokines and were efficient at priming and crosspriming naive CD8(+) T cells. A third DC population, CD14(-)CD207(-)CD1a(+) DC, which resides in the dermis, could activate CD8(+) T cells better than CD14(+) DCs but less efficiently than LCs. Thus, the human skin displays three DC subsets, two of which, i.e., CD14(+) DCs and LCs, display functional specializations, the preferential activation of humoral and cellular immunity, respectively.

Cross-priming CD8+ T cells by targeting antigens to human dendritic cells through DCIR.

We evaluated human CD8(+) T-cell responses generated by targeting antigens to dendritic cells (DCs) through various lectin receptors. We found the immunoreceptor tyrosine-based inhibitory motif-containing DC immunoreceptor (DCIR) to mediate potent cross-presentation. A single exposure to a low dose of anti-DCIR-antigen conjugate initiated antigen-specific CD8(+) T-cell immunity by all human DC subsets including ex vivo-generated DCs, skin-isolated Langerhans cells, and blood myeloid DCs and plasmacytoid DCs. The delivery of influenza matrix protein (FluMP) through DCIR resulted in expansion of FluMP-specific memory CD8(+) T cells. Enhanced specific CD8(+) T-cell responses were observed when an antigen was delivered to the DCs via DCIR, compared with those induced by a free antigen, or antigen conjugated to a control monoclonal antibody or delivered via DC-SIGN, another lectin receptor. DCIR targeting also induced primary CD8(+) T-cell responses against self (MART-1) and viral (HIV gag) antigens. Addition of Toll-like receptor (TLR) 7/8 agonist enhanced DCIR-mediated cross-presentation as well as cross-priming, particularly when combined with a CD40 signal. TLR7/8 activation was associated with increased expansion of the primed CD8(+) T cells, high production of interferon-γ and tumor necrosis factor-α, and reduced levels of type 2-associated cytokines. Thus, antigen targeting via the human DCIR receptor allows activation of specific CD8(+) T-cell immunity.

Systems Scale Interactive Exploration Reveals Quantitative and Qualitative Differences in Response to Influenza and Pneumococcal Vaccines

Systems immunology approaches were employed to investigate innate and adaptive immune responses to influenza and pneumococcal vaccines. These two non-live vaccines show different magnitudes of transcriptional responses at different time points after vaccination. Software solutions were developed to explore correlates of vaccine efficacy measured as antibody titers at day 28. These enabled a further dissection of transcriptional responses. Thus, the innate response, measured within hours in the peripheral blood, was dominated by an interferon transcriptional signature after influenza vaccination and by an inflammation signature after pneumococcal vaccination. Day 7 plasmablast responses induced by both vaccines was more pronounced after pneumococcal vaccination. Together, these results suggest that comparing global immune responses elicited by different vaccines will be critical to our understanding of the immune mechanisms underpinning successful vaccination.

The differential production of cytokines by human Langerhans cells and dermal CD14(+) DCs controls CTL priming.

We recently reported that human epidermal Langerhans cells (LCs) are more efficient than dermal CD14(+) DCs at priming naive CD8(+) T cells into potent CTLs. We hypothesized that distinctive dendritic cell (DC) cytokine expression profiles (ie, IL-15 produced by LCs and IL-10 expressed by dermal CD14(+) DCs) might explain the observed functional difference. Blocking IL-15 during CD8(+) T-cell priming reduced T-cell proliferation by ∼ 50%. These IL-15-deprived CD8(+) T cells did not acquire the phenotype of effector memory cells. They secreted less IL-2 and IFN-γ and expressed only low amounts of CD107a, granzymes and perforin, and reduced levels of the antiapoptotic protein Bcl-2. Confocal microscopy analysis showed that IL-15 is localized at the immunologic synapse of LCs and naive CD8(+) T cells. Conversely, blocking IL-10 during cocultures of dermal CD14(+) DCs and naive CD8(+) T cells enhanced the generation of effector CTLs, whereas addition of IL-10 to cultures of LCs and naive CD8(+) T cells inhibited their induction. TGF-β1 that is transcribed by dermal CD14(+) DCs further enhanced the inhibitory effect of IL-10. Thus, the respective production of IL-15 and IL-10 explains the contrasting effects of LCs and dermal CD14(+) DCs on CD8(+) T-cell priming.

Immunoglobulin-like transcript receptors on human dermal CD14+ dendritic cells act as a CD8-antagonist to control cytotoxic T cell priming

Human Langerhans cells (LCs) are highly efficient at priming cytolytic CD8+ T cells compared with dermal CD14+ dendritic cells (DCs). Here we show that dermal CD14+ DCs instead prime a fraction of naïve CD8+ T cells into cells sharing the properties of type 2 cytokine-secreting CD8+ T cells (TC2). Differential expression of the CD8-antagonist receptors on dermal CD14+ DCs, the Ig-like transcript (ILT) inhibitory receptors, explains the difference between the two types of DCs. Inhibition of CD8 function on LCs inhibited cytotoxic T lymphocytes (CTLs) and enhanced TC2 generation. In addition, blocking ILT2 or ILT4 on dermal CD14+ DCs enhanced the generation of CTLs and inhibited TC2 cytokine production. Lastly, addition of soluble ILT2 and ILT4 receptors inhibited CTL priming by LCs. Thus, ILT receptor expression explains the polarization of CD8+ T-cell responses by LCs vs. dermal CD14+ DCs.

Transcriptional fingerprints of antigen-presenting cell subsets in the human vaginal mucosa and skin reflect tissue-specific immune microenvironments

BackgroundDendritic cells localize throughout the body, where they can sense and capture invading pathogens to induce protective immunity. Hence, harnessing the biology of tissue-resident dendritic cells is fundamental for the rational design of vaccines against pathogens.MethodsHerein, we characterized the transcriptomes of four antigen-presenting cell subsets from the human vagina (Langerhans cells, CD14- and CD14+ dendritic cells, macrophages) by microarray, at both the transcript and network level, and compared them to those of three skin dendritic cell subsets and blood myeloid dendritic cells.ResultsWe found that genomic fingerprints of antigen-presenting cells are significantly influenced by the tissue of origin as well as by individual subsets. Nonetheless, CD14+ populations from both vagina and skin are geared towards innate immunity and pro-inflammatory responses, whereas CD14- populations, particularly skin and vaginal Langerhans cells, and vaginal CD14- dendritic cells, display both Th2-inducing and regulatory phenotypes. We also identified new phenotypic and functional biomarkers of vaginal antigen-presenting cell subsets.ConclusionsWe provide a transcriptional database of 87 microarray samples spanning eight antigen-presenting cell populations in the human vagina, skin and blood. Altogether, these data provide molecular information that will further help characterize human tissue antigen-presenting cell lineages and their functions. Data from this study can guide the design of mucosal vaccines against sexually transmitted pathogens.

Influenza vaccines differentially regulate the interferon response in human dendritic cell subsets

The monovalent H1N1 vaccine failed to promote human DC activation and to induce a type I IFN signature, which may have contributed to its limited efficacy. Influenz-ing interferon responses in dendritic cells Seasonal influenza vaccines have been produced and marketed for decades but are not always protective. Athale et al. tested a trivalent vaccine that outperformed the monovalent vaccine made by the same manufacturer for the ability to activate human dendritic cell subsets, which are crucial for launching adaptive immune responses. They discovered that both vaccines could activate plasmacytoid dendritic cells, but only the trivalent vaccine could induce antiviral interferon responses in other types of dendritic cells. Moreover, people immunized with the monovalent vaccine did not show early interferon responses in the blood, which were induced by trivalent vaccination. These intriguing results may help explain vaccine underperformance that is not due to antigenic mismatch. Human dendritic cells (DCs) play a fundamental role in the initiation of long-term adaptive immunity during vaccination against influenza. Understanding the early response of human DCs to vaccine exposure is thus essential to determine the nature and magnitude of maturation signals that have been shown to strongly correlate with vaccine effectiveness. In 2009, the H1N1 influenza epidemics fostered the commercialization of the nonadjuvanted monovalent H1N1 California vaccine (MIV-09) to complement the existing nonadjuvanted trivalent Fluzone 2009–2010 vaccine (TIV-09). In retrospective studies, MIV-09 displayed lower effectiveness than TIV-09. We show that TIV-09 induces monocyte-derived DCs (moDCs), blood conventional DCs (cDCs), and plasmacytoid DCs (pDCs) to express CD80, CD83, and CD86 and secrete cytokines. TIV-09 stimulated the secretion of type I interferons (IFNs) IFN-α and IFN-β and type III IFN interleukin-29 (IL-29) by moDC and cDC subsets. The vaccine also induced the production of IL-6, tumor necrosis factor, and the chemokines IFN-γ–inducible protein 10 (IP-10) and macrophage inflammatory protein–1β (MIP-1β). Conversely, MIV-09 did not induce the production of type I IFNs in moDCs and blood cDCs. Furthermore, it inhibited the TIV-09–induced secretion of type I IFNs by these DCs. However, both vaccines induced pDCs to secrete type I IFNs, indicating that different influenza vaccines activate distinct molecular signaling pathways in DC subsets. These results suggest that subtypes of nonadjuvanted influenza vaccines trigger immunity through different mechanisms and that the ability of a vaccine to induce an IFN response in DCs may offset the absence of adjuvant and increase vaccine efficacy.

Therapeutic HPV cancer vaccine targeted to CD40 elicits effective CD8+ T-cell immunity

In the U.S., HPV is responsible for more than 26,000 new cancer cases annually. A novel and effective immunotherapeutic vaccine against many types of HPV16-associated cancers was developed that supports targeting vaccines to dendritic cells via CD40. Human papillomavirus (HPV), particularly HPV16 and HPV18, can cause cancers in diverse anatomical sites, including the anogenital and oropharyngeal (throat) regions. Therefore, development of safe and clinically effective therapeutic vaccines is an important goal. Herein, we show that a recombinant fusion protein of a humanized antibody to CD40 fused to HPV16.E6/7 (αCD40-HPV16.E6/7) can evoke HPV16.E6/7-specific CD8+ and CD4+ T-cell responses in head-and-neck cancer patients in vitro and in human CD40 transgenic (hCD40Tg) mice in vivo. The combination of αCD40-HPV16.E6/7 and poly(I:C) efficiently primed HPV16.E6/7-specific T cells, particularly CD8+ T cells, in hCD40Tg mice. Inclusion of montanide enhanced HPV16.E6/7-specific CD4+, but not CD8+, T-cell responses. Poly(I:C) plus αCD40-HPV16.E6/7 was sufficient to mount both preventative and therapeutic immunity against TC-1 tumors in hCD40Tg mice, significantly increasing the frequency of HPV16-specific CD8+ CTLs in the tumors, but not in peripheral blood. In line with this, tumor volume inversely correlated with the frequency of HPV16.E6/7-specific CD8+ T cells in tumors, but not in blood. These data suggest that CD40-targeting vaccines for HPV-associated malignancies can provide a highly immunogenic platform with a strong likelihood of clinical benefit. Data from this study offer strong support for the development of CD40-targeting vaccines for other cancers in the future. Cancer Immunol Res; 4(10); 823–34. ©2016 AACR.