Batf3 selectively determines acquisition of CD8+ dendritic cell phenotype and function

An overview of host immune responses against Leishmania spp. infections

Leishmania spp. infections pose a significant global health challenge, affecting approximately 1 billion people across more than 88 endemic countries. This unicellular, obligate intracellular parasite causes a spectrum of diseases, ranging from localized cutaneous lesions to systemic visceral infections. Despite advancements in modern medicine and increased understanding of the parasite's etiology and associated diseases, treatment options remain limited to pentavalent antimonials, liposomal amphotericin B, and miltefosine. A deeper understanding of the interactions between immune and non-immune cells involved in the clearance of Leishmania spp. infections could uncover novel therapeutic strategies for this debilitating disease. This review highlights recent progress in elucidating how various cell types contribute to the regulation and resolution of Leishmania spp. infections.

TRIM33 plays a critical role in regulating dendritic cell differentiation and homeostasis by modulating Irf8 and Bcl2l11 transcription

The development of distinct dendritic cell (DC) subsets, namely, plasmacytoid DCs (pDCs) and conventional DC subsets (cDC1s and cDC2s), is controlled by specific transcription factors. IRF8 is essential for the fate specification of cDC1s. However, how the expression of Irf8 is regulated is not fully understood. In this study, we identified TRIM33 as a critical regulator of DC differentiation and maintenance. TRIM33 deletion in Trim33fl/fl Cre-ERT2 mice significantly impaired DC differentiation from hematopoietic progenitors at different developmental stages. TRIM33 deficiency downregulated the expression of multiple genes associated with DC differentiation in these progenitors. TRIM33 promoted the transcription of Irf8 to facilitate the differentiation of cDC1s by maintaining adequate CDK9 and Ser2 phosphorylated RNA polymerase II (S2 Pol II) levels at Irf8 gene sites. Moreover, TRIM33 prevented the apoptosis of DCs and progenitors by directly suppressing the PU.1-mediated transcription of Bcl2l11, thereby maintaining DC homeostasis. Taken together, our findings identified TRIM33 as a novel and crucial regulator of DC differentiation and maintenance through the modulation of Irf8 and Bcl2l11 expression. The finding that TRIM33 functions as a critical regulator of both DC differentiation and survival provides potential benefits for devising DC-based immune interventions and therapies.

Differential Response of Human Dendritic Cells upon Stimulation with Encapsulated or Non-Encapsulated Isogenic Strains of Porphyromonas gingivalis

During periodontitis, the extracellular capsule of Porphyromonas gingivalis favors alveolar bone loss by inducing Th1 and Th17 patterns of lymphocyte response in the infected periodontium. Dendritic cells recognize bacterial antigens and present them to T lymphocytes, defining their activation and polarization. Thus, dendritic cells could be involved in the Th1 and Th17 response induced against the P. gingivalis capsule. Herein, monocyte-derived dendritic cells were obtained from healthy individuals and then stimulated with different encapsulated strains of P. gingivalis or two non-encapsulated isogenic mutants. Dendritic cell differentiation and maturation were analyzed by flow cytometry. The mRNA expression levels for distinct Th1-, Th17-, or T-regulatory-related cytokines and transcription factors, as well as TLR2 and TLR4, were assessed by qPCR. In addition, the production of IL-1β, IL-6, IL-23, and TNF-α was analyzed by ELISA. The encapsulated strains and non-encapsulated mutants of P. gingivalis induced dendritic cell maturation to a similar extent; however, the pattern of dendritic cell response was different. In particular, the encapsulated strains of P. gingivalis induced higher expression of IRF4 and NOTCH2 and production of IL-1β, IL-6, IL-23, and TNF-α compared with the non-encapsulated mutants, and thus, they showed an increased capacity to trigger Th1 and Th17-type responses in human dendritic cells.

Concise review: The heterogenous roles of BATF3 in cancer oncogenesis and dendritic cells and T cells differentiation and function considering the importance of BATF3-dependent dendritic cells

The transcription factor, known as basic leucine zipper ATF-like 3 (BATF3), is a crucial contributor to the development of conventional type 1 dendritic cells (cDC1), which is definitely required for priming CD8 + T cell-mediated immunity against intracellular pathogens and malignancies. In this respect, BATF3-dependent cDC1 can bring about immunological tolerance, an autoimmune response, graft immunity, and defense against infectious agents such as viruses, microbes, parasites, and fungi. Moreover, the important function of cDC1 in stimulating CD8 + T cells creates an excellent opportunity to develop a highly effective target for vaccination against intracellular pathogens and diseases. BATF3 has been clarified to control the development of CD8α+ and CD103+ DCs. The presence of BATF3-dependent cDC1 in the tumor microenvironment (TME) reinforces immunosurveillance and improves immunotherapy approaches, which can be beneficial for cancer immunotherapy. Additionally, BATF3 acts as a transcriptional inhibitor of Treg development by decreasing the expression of the transcription factor FOXP3. However, when overexpressed in CD8 + T cells, it can enhance their survival and facilitate their transition to a memory state. BATF3 induces Th9 cell differentiation by binding to the IL-9 promoter through a BATF3/IRF4 complex. One of the latest research findings is the oncogenic function of BATF3, which has been approved and illustrated in several biological processes of proliferation and invasion.

Dendritic cell-derived exosomes (Dex): Underlying the role of exosomes derived from diverse DC subtypes in cancer pathogenesis

Exosomes are nanometric membrane vesicles of late endosomal origin that are released by most, if not all, cell types as a sophisticated means of intercellular communication. They play an essential role in the movement of materials and information between cells, transport a variety of proteins, lipids, RNA, and other vital data, and over time, they become an essential part of the drug delivery system and a marker for the early detection of many diseases. Dendritic cells have generated interest in cancer immunotherapy due to their ability to initiate and modify effective immune responses. Apart from their cytokine release and direct interactions with other cell types, DCs also emit nanovesicles, such as exosomes, that contribute to their overall activity. Numerous studies have demonstrated exosomes to mediate and regulate immune responses against cancers. Dendritic cell-derived exosomes (DCs) have attracted a lot of attention as immunotherapeutic anti-cancer treatments since it was found that they contain functional MHC-peptide complexes along with a variety of other immune-stimulating components that together enable immune cell-dependent tumor rejection. By enhancing tumor and immunosuppressive immune cells or changing a pro-inflammatory milieu to inhibit tumor advancement, exosomes generated from dendritic cells can initiate and support tumor growth. This study reviewed the immunogenicity of dendritic cell-derived exosomes and strategies for expanding their immunogenic potential as novel and effective anti-cancer therapies.

Celebrating 100 years of Immunology & Cell Biology - a special focus on the field of tumor immunology in Australia

In this Commentary article, as part of the 100-year celebrations of the journal, we reflect on the contribution of articles published in ICB in the field of tumor immunology. A highlight is a series of interviews conducted with three Australian-based ICB authors who have contributed key papers over the years: Rajiv Khanna, Delia Nelson and Ian Frazer.

IRF4 expression by lung dendritic cells drives acute but not Trm cell-dependent memory Th2 responses

Expression of the transcription factor interferon regulatory factor 4 (IRF4) is required for the development of lung conventional DCs type 2 (cDC2s) that elicit Th2 responses, yet how IRF4 functions in lung cDC2s throughout the acute and memory allergic response is not clear. Here, we used a mouse model that loses IRF4 expression after lung cDC2 development to demonstrate that mice with IRF4-deficient DCs display impaired memory responses to allergen. This defect in the memory response was a direct result of ineffective Th2 induction and impaired recruitment of activated effector T cells to the lung after sensitization. IRF4-deficient DCs demonstrated defects in their migration to the draining lymph node and in T cell priming. Finally, T cells primed by IRF4-competent DCs mediated potent memory responses independently of IRF4-expressing DCs, demonstrating that IRF4-expressing DCs are not necessary during the memory response. Thus, IRF4 controlled a program in mature DCs governing Th2 priming and effector responses, but IRF4-expressing DCs were dispensable during tissue-resident memory T cell-dependent memory responses.

Dendritic Cells: The Long and Evolving Road towards Successful Targetability in Cancer

Dendritic cells (DCs) are a unique myeloid cell lineage that play a central role in the priming of the adaptive immune response. As such, they are an attractive target for immune oncology based therapeutic approaches. However, targeting these cells has proven challenging with many studies proving inconclusive or of no benefit in a clinical trial setting. In this review, we highlight the known and unknown about this rare but powerful immune cell. As technologies have expanded our understanding of the complexity of DC development, subsets and response features, we are now left to apply this knowledge to the design of new therapeutic strategies in cancer. We propose that utilization of these technologies through a multiomics approach will allow for an improved directed targeting of DCs in a clinical trial setting. In addition, the DC research community should consider a consensus on subset nomenclature to distinguish new subsets from functional or phenotypic changes in response to their environment.

Albumin and interferon-β fusion protein serves as an effective vaccine adjuvant to enhance antigen-specific CD8+ T cell-mediated antitumor immunity

BACKGROUND

Type I interferons (IFN) promote dendritic cells maturation and subsequently enhance generation of antigen-specific CD8 +T cell for the control of tumor. Using type I interferons as an adjuvant to vaccination could prove to be a potent strategy. However, type I interferons have a short half-life. Albumin linked to a protein will prolong the half-life of the linked protein.

METHODS

In this study, we explored the fusion of albumin to IFNβ (Alb-IFNβ) for its functional activity both in vitro and in vivo. We determined the half-life of Alb-IFNβ following treatment in the serum, tumor, and tumor draining lymph nodes in both wild type and FcRn knockout mice. We characterized the ability of Alb-IFNβ to enhance antigen-specific CD8+ T cells using ovalbumin (OVA) or human papillomavirus (HPV) E7 long peptides. Next, we evaluated the therapeutic antitumor effect of coadministration of AlbIFNβ with antigenic peptides against HPVE7 expressing tumor and the treatment's ability to generate HPVE7 antigen specific CD8+ T cells. The contribution of the antitumor effect by lymphocytes was also examined by an antibody depletion experiment. The ability of Alb-IFNβ to serve as an adjuvant was tested using clinical grade therapeutic protein-based HPV vaccine, TACIN.

RESULTS

Alb-IFNβ retains biological function and does not alter the biological activity of IFNβ. In addition, Alb-IFNβ extends half-life of IFNβ in serum, lymph nodes and tumor. The coadministration of Alb-IFNβ with OVA or HPVE7 antigenic peptides enhances antigen-specific CD8 +T cell immunity, and in a TC-1 tumor model results in a significant therapeutic antitumor effect. We found that CD8 +T cells and dendritic cells, but not CD4 +T cells, are important for the observed antitumor therapeutic effect mediated by Alb-IFNβ. Finally, Alb-IFNβ served as a potent adjuvant for TA-CIN for the treatment of HPV antigen expressing tumors.

CONCLUSIONS

Overall, Alb-IFNβ serves as a potent adjuvant for enhancement of strong antigen-specific CD8 +T cell antitumor immunity, reduction of tumor burden, and increase in overall survival. Alb-IFNβ potentially can serve as an innovative adjuvant for the development of vaccines for the control of infectious disease and cancer.

Anti-inflammatory effects of B vitamins protect against tau hyperphosphorylation and cognitive impairment induced by 1,2 diacetyl benzene: An in vitro and in silico study

1,2 diacetyl benzene (DAB) penetrates the blood-brain barrier, causing neuroinflammation, tau hyperphosphorylation, and cognitive impairment. Converging evidence supports the anti-inflammatory effects of B vitamins on cognitive impairment, but the effects of B vitamins on cognitive impairment induced by DAB remain unclear. Here, we investigated the anti-inflammatory properties of B vitamins in DAB-stimulated human neuroblastoma SH-SY5Y cells. In this in-silico analysis, we investigated the genes, transcription factors, miRNAs, and sponges linked with DAB, B vitamins and the pathogenesis of cognitive impairment. We found vitamins B1, B2, and B3 had anti-inflammatory properties in DAB-stimulated SH-SY5Y cells, possibly via inhibiting NF-κB activation. Furthermore, vitamins B1, B2, and B3 inhibited GSK-3β, β-amyloid, and tau hyperphosphorylation in SH-SY5Y cells. These vitamins can also modulate genes induced by DAB (IL1B, IL6, IL10, iNOS, COX2, NFκB, GSK3B, TNF, and APP) in SH-SY5Y cells. In silico analyses, inflammatory response related pathways, "Alzheimer's disease", "pathways of neurodegeneration-multiple disease", and "prolactin signaling pathway", were highlighted. Additionally, we explored a network-based approach to identify key genes, transcription factors, miRNAs, and pathways in cognitive impairment. The transcription factors NFKB2 and BATF3 were shown to be the most important in regulating genes. We also found eight significant miRNAs related to cognitive impairment, and these miRNAs were also validated by qPCR. Finally, we developed and tested in silico miRNA sponge sequences for these miRNAs.

IRF8 and BATF3 interaction enhances the cDC1 specific Pfkfb3 gene expression

Dendritic cells (DCs) play central role in innate as well as adaptive immune responses regulated by diverse DC subtypes that vary in terms of surface markers, transcriptional profile and functional responses. Generation of DC diversity from progenitor stage is tightly regulated by complex molecular inter-play between transcription factors. We earlier demonstrated that Batf3 and Id2 expression have a synergistic effect on the Irf8 directed classical cDC1 development. In present study, Bi-molecular fluorescence complementation assay suggested that IRF8 interacts with BATF3, and ID2 may aid cDC1 development independently. Genome wide recruitment analysis of IRF8 and BATF3 from different DC subtypes led to identification of the overlapping regions of occupancy by these two transcription factors. Further analysis of overlapping peaks of IRF8 and BATF3 occupancy in promoter region within the cDC1 subtype specific transcriptional pattern identified a metabolically important Pfkfb3 gene. Among various immune cell types; splenic cDC1 subtype displayed enhanced expression of Pfkfb3. Analysis of Irf8^-/-, Irf8^R294C and Batf3^DCKO DC confirmed direct regulation of Pfkfb3 enhanced expression specifically in cDC1 subtype. Further we show that inhibition of PFKFB3 enzymatic activity by a chemical agent PFK15 led to reduction in cDC1 subtype in both in vitro FLDC cultures as well as in vivo mouse spleens. Together, our study identified the direct regulation of cDC1 specific enhanced expression of Pfkfb3 in glycolysis and cDC1 biology.

Absence of Batf3 reveals a new dimension of cell state heterogeneity within conventional dendritic cells

Conventional dendritic cells (cDCs) are traditionally subdivided into cDC1 and cDC2 lineages. Batf3 is a cDC1-required transcription factor, and we observed that Batf3−/− mice harbor a population of cDC1-like cells co-expressing cDC2-associated surface molecules. Using single-cell RNA sequencing with integrated cell surface protein expression (CITE-seq), we found that Batf3−/− mitotic immature cDC1-like cells showed reduced expression of cDC1 features and increased levels of cDC2 features. In wild type, we also observed a proportion of mature cDC1 cells expressing surface features characteristic to cDC2 and found that overall cDC cell state heterogeneity was mainly driven by developmental stage, proliferation, and maturity. We detected population diversity within Sirpa+ cDC2 cells, including a Cd33+ cell state expressing high levels of Sox4 and lineage-mixed features characteristic to cDC1, cDC2, pDCs, and monocytes. In conclusion, these data suggest that multiple cDC cell states can co-express lineage-overlapping features, revealing a level of previously unappreciated cDC plasticity.

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Single-cell proteogenomics identifies additional layers of DC heterogeneity

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cDC diversity is driven by proliferation, developmental stage, and maturation

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Lack of Batf3 increases cDCs with lineage-mixed features

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Sox4+ cDCs represent a cell state of lineage-mixed features

Characterization of Gene Expression Signatures for the Identification of Cellular Heterogeneity in the Developing Mammary Gland

The developing mammary gland depends on several transcription-dependent networks to define cellular identities and differentiation trajectories. Recent technological advancements that allow for single-cell profiling of gene expression have provided an initial picture into the epithelial cellular heterogeneity across the diverse stages of gland maturation. Still, a deeper dive into expanded molecular signatures would improve our understanding of the diversity of mammary epithelial and non-epithelial cellular populations across different tissue developmental stages, mouse strains and mammalian species. Here, we combined differential mammary gland fractionation approaches and transcriptional profiles obtained from FACS-isolated mammary cells to improve our definitions of mammary-resident, cellular identities at the single-cell level. Our approach yielded a series of expression signatures that illustrate the heterogeneity of mammary epithelial cells, specifically those of the luminal fate, and uncovered transcriptional changes to their lineage-defined, cellular states that are induced during gland development. Our analysis also provided molecular signatures that identified non-epithelial mammary cells, including adipocytes, fibroblasts and rare immune cells. Lastly, we extended our study to elucidate expression signatures of human, breast-resident cells, a strategy that allowed for the cross-species comparison of mammary epithelial identities. Collectively, our approach improved the existing signatures of normal mammary epithelial cells, as well as elucidated the diversity of non-epithelial cells in murine and human breast tissue. Our study provides a useful resource for future studies that use single-cell molecular profiling strategies to understand normal and malignant breast development.

Levels of low-molecular-weight hyaluronan in periodontitis-treated patients and its immunostimulatory effects on CD4+ T lymphocytes

OBJECTIVES

During periodontitis, chronic inflammation triggers soft tissue breakdown, and hyaluronan is degraded into fragments of low molecular weight (LMW-HA). This investigation aimed to elucidate whether LMW-HA fragments with immunogenic potential on T lymphocytes remain in periodontal tissues after periodontal treatment.

MATERIALS AND METHODS

GCF samples were obtained from 15 periodontitis-affected patients and the LMW-HA, RANKL, and OPG levels were analyzed before and after 6 months of periodontal treatment by ELISA. Eight healthy individuals were analyzed as controls. Besides, human T lymphocytes were purified, exposed to infected dendritic cells, and pulsed with LMW-HA. Non-treated T lymphocytes were used as control. The expression levels of the transcription factors and cytokines that determine the Th1, Th17, and Th22 lymphocyte differentiation and function were analyzed by RT-qPCR. Similarly, the expression levels of RANKL and CD44 were analyzed.

RESULTS

In the GCF samples of periodontitis-affected patients, higher levels of LMW-HA were detected when compared with those of healthy individuals (52.1 ± 15.4 vs. 21.4 ± 12.2, p < 0.001), and these increased levels did not decrease after periodontal therapy (52.1 ± 15.4 vs. 45.7 ± 15.9, p = 0.158). Similarly, the RANKL levels and RANKL/OPG ratios did not change after periodontal therapy. Furthermore, in human T lymphocytes, LMW-HA induced higher expression levels of the Th1, Th17, and Th22-related transcription factors and cytokines, as well as CD44 and RANKL, as compared with non-treated cells.

CONCLUSIONS

In some patients, increased levels of LMW-HA persist in periodontal tissues after conventional periodontal therapy, and these remaining LMW-HA fragments with immunostimulatory potential could induce the polarization of a pathologic Th1/Th17/Th22-pattern of immune response on T lymphocytes.

CLINICAL RELEVANCE

The persistence of increased levels of LMW-HA in periodontal tissues after periodontal therapy could favor the recurrence of the disease and further breakdown of periodontal supporting tissues.

Host CD8α+ and CD103+ dendritic cells prime transplant antigen-specific CD8+ T cells via cross-dressing

The participation of dendritic cells (DCs) in CD8⁺ T-cell-mediated allograft rejection is a long-standing question of great clinical relevance for tissue transplantation. Here, we show that Batf3^-/- mice demonstrate delayed allo-skin graft rejection and are deficient in priming allo-specific CD8⁺ T cells. Batf3^-/- mouse priming is restored by transferring either purified CD8α⁺ or CD103⁺ DCs, demonstrating the critical role of these cells in alloreactivity. Using D^b -restricted antiviral F5 transgenic T-cell receptor T cells, which we demonstrate are alloreactive with H-2K^d , we show that cross-dressing of CD8α⁺ and CD103⁺ primes CD8⁺ T-cell or allo-specific responses in vitro and in vivo. These findings suggest novel strategies for moderating tissue rejection based on interfering with DC cross-dressing or subsequent interaction with T cells.

Merocytic Dendritic Cells Compose a Conventional Dendritic Cell Subset with Low Metabolic Activity

Conventional dendritic cells (cDCs) are arguably the most potent APCs that induce the activation of naive T cells in response to pathogens. In addition, at steady-state, cDCs help maintain immune tolerance. Two subsets of cDCs have been extensively characterized, namely cDC1 and cDC2, each contributing differently to immune responses. Recently, another dendritic cell (DC) subset, termed merocytic DCs (mcDCs), was defined. In contrast to both cDC1 and cDC2, mcDCs reverse T cell anergy, properties that could be exploited to potentiate cancer treatments. Yet, whether mcDCs represent an unconventional DC or a cDC subset remains to be defined. In this article, we further characterize mcDCs and find that they bear true characteristics of cDC subsets. Indeed, as for cDCs, mcDCs express the cDC-restricted transcription factor Zbtb46 and display very potent APC activity. In addition, mcDC population dynamics parallels that of cDC1 and cDC2 in both reconstitution kinetic studies and parabiotic mice. We next investigated their relatedness to cDC1 and cDC2 and demonstrate that mcDCs are not dependent on cDC1-related Irf8 and Batf3 transcription factors, are dependent on Irf4, a cDC2-specific transcription factor, and express a unique transcriptomic signature. Finally, we find that cDC1, cDC2, and mcDCs all present with different metabolic phenotypes, in which mcDCs exhibit the lowest glucose uptake activity and mcDC survival is the least affected by glycolysis inhibition. Defining the properties of mcDCs in mice may help identify a functionally equivalent subset in humans leading to the development of innovative cancer immunotherapies.

Dendritic cell subsets and locations

Dendritic cells (DCs) are a unique class of immune cells that act as a bridge between innate and adaptive immunity. The discovery of DCs by Cohen and Steinman in 1973 laid the foundation for DC biology, and the advances in the field identified different versions of DCs with unique properties and functions. DCs originate from hematopoietic stem cells, and their differentiation is modulated by Flt3L. They are professional antigen-presenting cells that patrol the environmental interphase, sites of infection, or infiltrate pathological tissues looking for antigens that can be used to activate effector cells. DCs are critical for the initiation of the cellular and humoral immune response and protection from infectious diseases or tumors. DCs can take up antigens using specialized surface receptors such as endocytosis receptors, phagocytosis receptors, and C type lectin receptors. Moreover, DCs are equipped with an array of extracellular and intracellular pattern recognition receptors for sensing different danger signals. Upon sensing the danger signals, DCs get activated, upregulate costimulatory molecules, produce various cytokines and chemokines, take up antigen and process it and migrate to lymph nodes where they present antigens to both CD8 and CD4 T cells. DCs are classified into different subsets based on an integrated approach considering their surface phenotype, expression of unique and conserved molecules, ontogeny, and functions. They can be broadly classified as conventional DCs consisting of two subsets (DC1 and DC2), plasmacytoid DCs, inflammatory DCs, and Langerhans cells.

HPV16 E7-Driven Epithelial Hyperplasia Promotes Impaired Antigen Presentation and Regulatory T-Cell Development

Human papillomaviruses infect keratinocytes and can lead to hyperproliferative dysplasia and malignant transformation if not cleared by the immune system. Human papillomavirus has evolved an array of mechanisms to evade and manipulate the immune system to improve replication efficiency and promote persistent infection. We here demonstrate that hyperproliferative skin expressing the high-risk human papillomavirus 16 E7 oncogene as a transgene drives immunomodulation of dendritic cells (DCs), resulting in reduced capacity to take up antigen and prime effector CD4⁺ T cell responses. The phenotype of DCs in the E7-expressing hyperproliferative skin was not reversible by activation through intradermal immunization. Naïve CD4⁺ T cells primed by E7-driven hyperproliferative skin acquired FoxP3 expression and an anergic phenotype. DC and T help modulation was dependent on E7-retinoblastoma protein interaction-driven epithelial hyperproliferation, rather than on expression of E7. Inhibition of binding of E7 to retinoblastoma protein, and of consequent epithelial hyperplasia, was associated with normal skin DC phenotype, and T helper type 1 effector responses to immunization were restored. We conclude that human papillomavirus-induced epithelial hyperplasia modulates epithelial DCs and inhibits T helper type 1 immunity while polarizing T-cell differentiation to a regulatory or anergic phenotype.

A low inflammatory, Langerhans cell-targeted microprojection patch to deliver ovalbumin to the epidermis of mouse skin

In a low inflammatory skin environment, Langerhans cells (LCs) - but not dermal dendritic cells (dDCs) - contribute to the pivotal process of tolerance induction. Thus LCs are a target for specific-tolerance therapies. LCs reside just below the stratum corneum, within the skin's viable epidermis. One way to precisely deliver immunotherapies to LCs while remaining minimally invasive is with a skin delivery device such as a microprojection arrays (MPA). Today's MPAs currently achieve rapid delivery (e.g. within minutes of application), but are focussed primarily at delivery of therapeutics to the dermis, deeper within the skin. Indeed, no MPA currently delivers specifically to the epidermal LCs of mouse skin. Without any convenient, pre-clinical device available, advancement of LC-targeted therapies has been limited. In this study, we designed and tested a novel MPA that delivers ovalbumin to the mouse epidermis (eMPA) while maintaining a low, local inflammatory response (as defined by low erythema after 24 h). In comparison to available dermal-targeted MPAs (dMPA), only eMPAs with larger projection tip surface areas achieved shallow epidermal penetration at a low application energy. The eMPA characterised here induced significantly less erythema after 24 h (p = 0.0004), less epidermal swelling after 72 h (p < 0.0001) and 52% less epidermal cell death than the dMPA. Despite these differences in skin inflammation, the eMPA and dMPA promoted similar levels of LC migration out of the skin. However, only the eMPA promoted LCs to migrate with a low MHC II expression and in the absence of dDC migration. Implementing this more mouse-appropriate and low-inflammatory eMPA device to deliver potential immunotherapeutics could improve the practicality and cell-specific targeting of such therapeutics in the pre-clinical stage. Leading to more opportunities for LC-targeted therapeutics such as for allergy immunotherapy and asthma.

The COX2 Effector Microsomal PGE2 Synthase 1 is a Regulator of Immunosuppression in Cutaneous Melanoma

PURPOSE

Microsomal prostaglandin E2 synthase 1 (mPGES1) was evaluated as an important downstream effector of the COX2 pathway responsible for tumor-mediated immunosuppression in melanoma.

EXPERIMENTAL DESIGN

The analysis of a stage III melanoma tissue microarray (n = 91) was performed to assess the association between mPGES1, COX2, CD8, and patient survival. Pharmacologic inhibitors and syngeneic mouse models using PTGES-knockout (KO) mouse melanoma cell lines were used to evaluate the mPGES1-mediated immunosuppressive function.

RESULTS

We observed correlations in expression and colocalization of COX2 and mPGES1, which are associated with increased expression of immunosuppressive markers in human melanoma. In a syngeneic melanoma mouse model, PTGES KO increased melanoma expression of PD-L1, increased infiltration of CD8a+ T cells, and CD8a+ dendritic cells into tumors and suppressed tumor growth. Durable tumor regression was observed in mice bearing PTGES KO tumors that were given anti-PD-1 therapy. Analysis of a stage III melanoma tissue microarray revealed significant associations between high mPGES1 expression and low CD8+ infiltration, which correlated with a shorter patient survival.

CONCLUSIONS

Our results are the first to illustrate a potential role for mPGES1 inhibition in melanoma immune evasion and selective targeting in supporting the durability of response to PD-1 checkpoint immunotherapy. More research effort in this drug development space is needed to validate the use of mPGES1 inhibitors as safe treatment options.

Immunostimulatory activity of low-molecular-weight hyaluronan on dendritic cells stimulated with Aggregatibacter actinomycetemcomitans or Porphyromonas gingivalis

OBJECTIVES

Periodontitis is a chronic inflammatory disease characterized by tooth-supporting tissue destruction, which is elicited by the host's immune response triggered against periodonto-pathogen bacteria. During periodontal tissue destruction, extracellular matrix components are metabolized and fragmented. Some extracellular matrix component-derived fragments, such as low-molecular-weight hyaluronan (LMW-HA), have potent immunogenic potential, playing a role as damage-associated molecular patterns (DAMPs) during activation of immune cells. Dendritic cells (DCs) play a central role in the host's immune response displayed during periodontitis; thus, this study aimed to analyze whether LMW-HA has an immunostimulatory activity on DCs when stimulated with periodonto-pathogen bacteria.

MATERIALS AND METHODS

LMW-HA-treated and non-treated DCs were stimulated with Aggregatibacter actinomycetemcomitans or Porphyromonas gingivalis and the mRNA expression for cytokines tumor necrosis factor-α (TNF-alpha), interleukin-1β (IL-1B), interleukin-6 (IL-6), and interleukin-23 (IL-23A) was quantified by RT-qPCR. In addition, transcription factors interferon regulatory factor 4 (IRF4), interferon regulatory factor 8 (IRF8), neurogenic locus notch homolog protein 2 (NOTCH2), and basic leucine zipper ATF-like transcription factor 3 (BATF3), involved in DC activation, were analyzed.

RESULTS

Higher expression levels of TNF-alpha, IL-1B, IL-6, and IL-23A were detected in LMW-HA-treated DCs after bacterial infection, as compared with non-treated DCs. When LMW-HA-treated DCs were infected with A. actinomycetemcomitans, higher levels of IRF4, NOTCH2, and BATF3 were detected compared with non-treated cells; whereas against P. gingivalis infection, increased levels of IRF4 and NOTCH2 were detected.

CONCLUSION

LMW-HA plays an immunostimulatory role on the immune response triggered by DCs during infection with A. actinomycetemcomitans or P. gingivalis.

CLINICAL RELEVANCE

Detection of extracellular matrix component-derived fragments produced during periodontal tissue destruction, such as LMW-HA, could explain at least partly unsuccessful periodontal treatment and the chronicity of the disease.