Tumor immunogenicity regulates host immune responses, and conventional dendritic cell type 2 uptakes the majority of tumor antigens in an orthotopic lung cancer model.

Human lung cancer carries high genetic alterations, expressing high tumor-specific neoantigens. Although orthotopic murine lung cancer models recapitulate many characteristics of human lung cancers, genetically engineered mouse models have fewer somatic mutations than human lung cancer, resulting in scarce immune cell infiltration and deficient immune responses. The endogenous mouse lung cancer model driven by Kras mutation and Trp53 deletion (KP model) has minimal immune infiltration because of a scarcity of neoantigens. Fine-tuning tumor antigenicity to trigger the appropriate level of antitumor immunity would be key to investigating immune responses against human lung cancer. We engineered the KP model to express antigens of OVA peptides (minOVA) as neoantigens along with ZsGreen, a traceable fluorescent conjugate. The KP model expressing minOVA exhibited stronger immunogenicity with higher immune cell infiltration comprised of CD8+ T cells and CD11c+ dendritic cells (DCs). Consequently, the KP model expressing minOVA exhibits suppressed tumor growth compared to its origin. We further analyzed tumor-infiltrated DCs. The majority of ZsGreen conjugated with minOVA was observed in the conventional type 2 DCs (cDC2), whereas cDC1 has minimal. These data indicate that tumor immunogenicity regulates host immune responses, and tumor neoantigen is mostly recognized by cDC2 cells, which may play a critical role in initiating antitumor immune responses in an orthotopic murine lung cancer model.

Deciphering the role of LGALS2: insights into tertiary lymphoid structure-associated dendritic cell activation and immunotherapeutic potential in breast cancer patients.

Recent advances in cancer research have highlighted the pivotal role of tertiary lymphoid structures (TLSs) in modulating immune responses, particularly in breast cancer (BRCA). Here, we performed an integrated analysis of bulk transcriptome data from over 6000 BRCA samples using biological network-based computational strategies and machine learning (ML) methods, and identified LGALS2 as a key marker within TLSs. Single-cell sequencing and spatial transcriptomics uncover the role of LGALS2 in TLS-associated dendritic cells (DCs) stimulation and reveal the complexity of the tumor microenvironment (TME) at both the macro and micro levels. Elevated LGALS2 expression correlates with prolonged survival, which is associated with a robust immune response marked by diverse immune cell infiltration and active anti-tumor pathways leading to a 'hot' tumor microenvironment. The colocalization of LGALS2 with TLS-associated DCs and its role in immune activation in BRCA were confirmed by hematoxylin-eosin (HE), immunohistochemistry (IHC), and in vivo validation analyses. The identification of LGALS2 as a key factor in BRCA not only highlights its therapeutic potential in novel TLS-directed immunotherapy but also opens new avenues in patient stratification and treatment selection, ultimately improving clinical management.

Blastic plasmacytoid dendritic cell neoplasm: Two case reports.

BACKGROUND: Blastic plasmacytoid dendritic cell tumor (BPDCN) is a rare and highly invasive lymphohematopoietic tumor that originates from plasmacytoid dendritic cells. BPDCN has an extremely poor prognosis. Skin lesions are usually the first manifestation of BPDCN, although the tumor may also invade the bone marrow, lymph nodes, peripheral blood, and other parts of the body, leading to several other manifestations, requiring further differentiation through skin biopsy and immunohistochemistry. CASE SUMMARY: In the present paper, the cases of 2 patients diagnosed with BPDCN are discussed. The immunohistochemistry analysis of these 2 patients revealed positivity for CD4, CD56, and CD123. Currently, no standard chemotherapy regimen is available for BPDCN. Therefore, intensive therapy for acute lymphoblastic leukemia was applied as the treatment method for these 2 cases. CONCLUSION: Although allogeneic bone marrow transplantation could be further effective in prolonging the median survival the ultimate prognosis was unfavorable. Future treatment modalities tailored for elderly patients will help prolong survival.

Erratum: First step results from a phase II study of a dendritic cell vaccine in glioblastoma patients (CombiG-vax).

[This corrects the article DOI: 10.3389/fimmu.2024.1404861.].

Boosting immunotherapy efficacy: Empowering the Potency of Dendritic cells loaded with breast cancer lysates through CTLA-4 suppression.

Anticancer immunotherapies with a dendritic Cell (DC) basis are becoming more popular. However, it has been suggested that the tumor's immunosuppressive mechanisms, such as inhibitory immunological checkpoint molecules, reduce the effectiveness of anticancer immunogenicity mediated by DC. Thus, overcoming immune checkpoints and inducing effective antigen-specific T-cell responses uniquely produced with malignant cells represent the key challenges. Among the inhibitory immune checkpoints, DCs' ability to mature and present antigens is decreased by CTLA-4 expression. Consequently, we hypothesized that by expressing CTLA-4 cells on DCs, the T cells' activation against tumor antigens would be suppressed when confronted with these antigens presented by DCs. In this research, by loading cell lysate of breast cancer (BC) on DCs and the other hand by inhibiting the induction of CTLA-4 using small interfering RNA (siRNA), we assessed the functional activities and phenotypes of DCs, and also the responses associated with T-cells following co-culture DC/T cell. Our research has shown that the suppression of CTLA-4 enhanced the stimulating capabilities of DCs. Additionally, CTLA-4-suppressed BC cell lysate-loaded DCs produced more IL-4 and IFN-ϒ and increased T cell induction in contrast to DCs without CTLA-4 suppression. Together, our data point to CTLA-4-suppressed DCs loaded with BC cell lysate as a potentially effective treatment method. However, further research is required before employing this method in therapeutic contexts.

Site-discordant expression of myeloid cell nuclear differentiation antigen in blastic plasmacytoid dendritic cell neoplasm.

OBJECTIVES: Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a rare and aggressive hematologic neoplasm that can show clinical, morphologic, and immunophenotypic overlap with acute myeloid leukemia. Myeloid cell nuclear differentiation antigen (MNDA) is a nuclear protein expressed by myelomonocytic cells previously reported to be reliably absent in BPDCN and proposed as a useful adjunct for the distinction of BPDCN and acute myeloid leukemia. We encountered a case of BPDCN that showed strong nuclear expression of MNDA in bone marrow and breast samples and weak to absent expression in skin samples, prompting us to reevaluate the expression of MNDA in BPDCN. METHODS: We collected all available BPDCN cases from the Stanford University archives collected in the past 10 years and subjected them to MNDA immunohistochemistry. In select cases, molecular profiling by next-generation sequencing was performed. RESULTS: We found 4 cases (of 8 total examined [50%]) with convincing site-discordant MNDA expression. This expression was seen in 3 of 6 (50%) bone marrow samples, 1 of 2 (50%) breast soft tissue samples, and 3 of 14 (up to 21%) skin samples and was not obviously predicted by age, sex, history of myeloid neoplasm, or treatment history. In 2 cases, MNDA was strongly expressed in 2 distinct sites (breast/bone marrow, skin/bone marrow) and negative in subsequent samples. CONCLUSIONS: Our findings suggest that MNDA expression in BPDCN is anatomic site dependent and transient, with noncutaneous infiltrates showing more frequent expression than cutaneous infiltrates. These results caution against the use of MNDA to exclude BPDCN when considering the differential diagnosis of a blastic extramedullary infiltrate.

Tumor lysate particle only vaccine (TLPO) vs. Tumor lysate particle-loaded, dendritic cell vaccine (TLPLDC) to prevent recurrence in resected stage III/IV melanoma patients: Results of a phase I/IIa trial.

BACKGROUND: The autologous tumor lysate, particle-loaded, dendritic cell (TLPLDC) vaccine is produced from dendritic cells (DC) loaded ex vivo with autologous tumor lysate (TL). TLPLDC has been shown to decrease recurrence in resected Stage III/IV melanoma patients in a Phase IIb trial. The TL particle only (TLPO) vaccine is produced by loading of yeast cell wall particles with autologous TL and direct injection allowing for in vivo DC loading. We have compared the TLPO and TLPLDC vaccines in an embedded Phase I/IIa trial of a larger Phase IIb trial of the TLPLDC vaccine. METHODS: Patients rendered clinically disease-free after surgery were randomized 2:1 to receive the TLPO or TLPLDC vaccine and followed for recurrence and death. Patients had scheduled intradermal inoculations at 0, 1, 2, 6, 12, and 18 months after enrollment. Kaplan-Meier and log-rank analysis were used to compare disease-free survival (DFS) and overall survival (OS) in an intention-to-treat (ITT) analysis. RESULTS: Sixty-three patients were randomized, 43 TLPO and 20 TLPLDC. Patients randomized to the TLPO arm were more likely to be female (37.2% vs. 10.0 %, p = 0.026), but otherwise no significant clinicopathological differences were identified. No differences in related adverse events (AE) were found between treatment arms. At a median follow-up of 20.5 months, the DFS (60.8% vs. 58.7 %, p = 0.714) and OS (94.6% vs. 93.8 %, p = 0.966) were equivalent between the TLPO and TLPLDC groups, respectively. No statistical differences were found in subgroup analyses between vaccine types, which accounted for receipt of immunotherapy and the use of G-CSF pre-blood draw. CONCLUSIONS: In a randomized, double-blind Phase I/IIa trial, there were no differences in DFS or OS in resected Stage III/IV melanoma patients receiving adjuvant TLPO versus TLPLDC vaccines. Given manufacturing advantages, further efficacy testing of TLPO is warranted in a Phase III trial.

Blastic plasmacytoid dendritic cell neoplasm: a short review and update.

Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a rare hematologic neoplasm (less than 1% of primary cutaneous lymphomas and acute leukemia) with a highly aggressive clinical course and frequent skin, bone marrow and central nervous system involvement. Even though there is often an early response to chemotherapy, leukemic dissemination relapses are very common and result in poor outcomes, with a median overall survival of 8 to 14 months in the first-line setting using standard combination chemotherapy regimens. Almost 90% of patients experience skin involvement as their initial site of infection, where BPDCN may stay restricted for weeks or even months until a swift secondary phase involving multiple organs takes place. Consequently, it is crucial to suspect and identify early skin lesions, as well as to conduct and report a skin biopsy as soon as possible. In order to diagnose and treat BPDCN, a multidisciplinary strategy involving collaboration between pathologists, hematologists, and dermatologists is unquestionably essential.

A rare case of an EBV-positive inflammatory follicular dendritic cell tumor of the spleen.

Epstein-Barr virus positive inflammatory pseudotumor follicular dendritic cell sarcoma (EBV+ FDCS) is a rare indolent neoplasm that presents primarily in the spleen and liver. We display a case of EBV+ FDCS in the spleen, its clinic-pathologic properties, and treatment. Our patient was evaluated following an incidental finding of a splenic mass on imaging after a traumatic injury. Computed tomography and magnetic resonance imaging both confirmed a well-circumscribed lesion in the spleen. Consequently, the patient underwent a robotic-assisted diagnostic splenectomy. Histologic examination revealed portions of spleen with partial effacement of tissue architecture by a well-circumscribed nonencapsulated mass displaying atypical, spindled cells-positive for EBER (CISH), EBV LMP1, smooth muscle actin, and clusterin-mixed inflammatory elements, and interspersed small lymphocytes.

Seno-antigen-pulsed dendritic cell vaccine induce anti-aging immunity to improve adipose tissue senescence and metabolic abnormalities.

Anti-aging immunity induced by vaccines was recently reported to enable the elimination of senescent cells. However, the initial immune response to vaccination declines with age, and there is evidence that elderly dendritic cells (DCs) have a reduced capacity to stimulate T cells. Identification of alternative anti-aging vaccine is therefore warranted. Here, we developed a DC vaccine that delivers a cationic protein (CP) fused with the seno-antigen peptides Gpnmb (Gpnmb-CP) into DCs. The Gpnmb-CP-pulsed DC vaccine (Gpnmb-CP-DC) efficiently presented antigens and activated CD8+ T cells, leading to enhanced immune cytotoxicity and memory responses in CD8+ T cells. Thus, the targeted anti-aging immunity triggered by Gpnmb-CP-DC has the ability to selectively eliminate senescent adipocytes and effectively improve age-related metabolic abnormalities in both high-fat diet (HFD)-induced young and aged mice models, as well as in natural aging mouse model. In contrast, the Gpnmb-CP protein vaccine exhibits minimal efficacy in aged mice model. Furthermore, we observed a decreased phagocytic capacity for antigens in aging DCs, accompanied by an upregulation of the immune checkpoint PDL1 expression and a noticeable decline in activated CD8+ T cell. Hence, Gpnmb-CP-DC emerges as a promising vaccine candidate, demonstrating the capacity to induce potent anti-aging immunity, mitigating adipose tissue senescence and metabolic abnormalities, while resilient to the senescent environment of the organism.

Evaluating Nanoparticulate Vaccine Formulations for Effective Antigen Presentation and T-Cell Proliferation Using an In Vitro Overlay Assay.

Inducing T lymphocyte (T-cell) activation and proliferation with specificity against a pathogen is crucial in vaccine formulation. Assessing vaccine candidates' ability to induce T-cell proliferation helps optimize formulation for its safety, immunogenicity, and efficacy. Our in-house vaccine candidates use microparticles (MPs) and nanoparticles (NPs) to enhance antigen stability and target delivery to antigen-presenting cells (APCs), providing improved immunogenicity. Typically, vaccine formulations are screened for safety and immunostimulatory effects using in vitro methods, but extensive animal testing is often required to assess immunogenic responses. We identified the need for a rapid, intermediate screening process to select promising candidates before advancing to expensive and time-consuming in vivo evaluations. In this study, an in vitro overlay assay system was demonstrated as an effective high-throughput preclinical testing method to evaluate the immunogenic properties of early-stage vaccine formulations. The overlay assay's effectiveness in testing particulate vaccine candidates for immunogenic responses has been evaluated by optimizing the carboxyfluorescein succinimidyl ester (CFSE) T-cell proliferation assay. DCs were overlaid with T-cells, allowing vaccine-stimulated DCs to present antigens to CFSE-stained T-cells. T-cell proliferation was quantified using flow cytometry on days 0, 1, 2, 4, and 6 upon successful antigen presentation. The assay was tested with nanoparticulate vaccine formulations targeting Neisseria gonorrhoeae (CDC F62, FA19, FA1090), measles, H1N1 flu prototype, canine coronavirus, and Zika, with adjuvants including Alhydrogel® (Alum) and AddaVax™. The assay revealed robust T-cell proliferation in the vaccine treatment groups, with variations between bacterial and viral vaccine candidates. A dose-dependent study indicated immune stimulation varied with antigen dose. These findings highlight the assay's potential to differentiate and quantify effective antigen presentation, providing valuable insights for developing and optimizing vaccine formulations.

The post-viral GPNMB+ immune niche persists in long-term Covid, asthma, and COPD.

Epithelial injury calls for a regenerative response from a coordinated network of epithelial stem cells and immune cells. Defining this network is key to preserving the repair process for acute resolution, but also for preventing a remodeling process with chronic dysfunction. We recently identified an immune niche for basal-epithelial stem cells using mouse models of injury after respiratory viral infection. Niche function depended on an early sentinel population of monocyte-derived dendritic cells (moDCs) that provided ligand GPNMB to basal-ESC receptor CD44 for reprogramming towards chronic lung disease. These same cell and molecular control points worked directly in mouse and human basal-ESC organoids, but the findings were not yet validated in vivo in human disease. Further, persistence of GPNMB expression in moDCs and M2-macrophages in mouse models suggested utility as a long-term disease biomarker in humans. Here we show increased expression of GPNMB localized to moDC-macrophage populations in lung tissue samples from long-term Covid, asthma, and COPD. The findings thereby provide initial evidence of a persistent and correctable pathway from acute injury to chronic disease with implications for cellular reprogramming and inflammatory memory.

Dynamic glycolytic reprogramming effects on dendritic cells in pancreatic ductal adenocarcinoma.

BACKGROUND: Pancreatic ductal adenocarcinoma tumors exhibit resistance to chemotherapy, targeted therapies, and even immunotherapy. Dendritic cells use glucose to support their effector functions and play a key role in anti-tumor immunity by promoting cytotoxic CD8+ T cell activity. However, the effects of glucose and lactate levels on dendritic cells in pancreatic ductal adenocarcinoma are unclear. In this study, we aimed to clarify how glucose and lactate can impact the dendritic cell antigen-presenting function and elucidate the relevant mechanisms. METHODS: Glycolytic activity and immune cell infiltration in pancreatic ductal adenocarcinoma were evaluated using patient-derived organoids and resected specimens. Cell lines with increased or decreased glycolysis were established from KPC mice. Flow cytometry and single-cell RNA sequencing were used to evaluate the impacts on the tumor microenvironment. The effects of glucose and lactate on the bone marrow-derived dendritic cell antigen-presenting function were detected by flow cytometry. RESULTS: The pancreatic ductal adenocarcinoma tumor microenvironment exhibited low glucose and high lactate concentrations from varying levels of glycolytic activity in cancer cells. In mouse transplantation models, tumors with increased glycolysis showed enhanced myeloid-derived suppressor cell infiltration and reduced dendritic cell and CD8+ T cell infiltration, whereas tumors with decreased glycolysis displayed the opposite trends. In three-dimensional co-culture, increased glycolysis in cancer cells suppressed the antigen-presenting function of bone marrow-derived dendritic cells. In addition, low-glucose and high-lactate media inhibited the antigen-presenting and mitochondrial functions of bone marrow-derived dendritic cells. CONCLUSIONS: Our study demonstrates the impact of dynamic glycolytic reprogramming on the composition of immune cells in the tumor microenvironment of pancreatic ductal adenocarcinoma, especially on the antigen-presenting function of dendritic cells.

cGAS activation in classical dendritic cells causes autoimmunity in TREX1-deficient mice.

Detection of cytosolic DNA by the cyclic GMP-AMP (cGAMP) synthase (cGAS)-stimulator of interferon genes (STING) pathway provides immune defense against pathogens and cancer but can also cause autoimmunity when overactivated. The exonuclease three prime repair exonuclease 1 (TREX1) degrades DNA in the cytosol and prevents cGAS activation by self-DNA. Loss-of-function mutations of the TREX1 gene are linked to autoimmune diseases such as Aicardi-Goutières syndrome, and mice deficient in TREX1 develop lethal inflammation in a cGAS-dependent manner. In order to determine the type of cells in which cGAS activation drives autoinflammation, we generated conditional cGAS knockout mice on the Trex1-/- background. Here, we show that genetic ablation of the cGAS gene in classical dendritic cells (cDCs), but not in macrophages, was sufficient to rescue Trex1-/- mice from all observed disease phenotypes including lethality, T cell activation, tissue inflammation, and production of antinuclear antibodies and interferon-stimulated genes. These results show that cGAS activation in cDC causes autoinflammation in response to self-DNA accumulated in the absence of TREX1.

Topical histone deacetylase inhibitor remetinostat improves IMQ-induced psoriatic dermatitis via suppressing dendritic cell maturation and keratinocyte differentiation and inflammation.

Psoriasis is a chronic inflammatory skin disease characterized by excessive proliferation of keratinocytes and infiltration of immune cells. Although psoriasis has entered the era of biological treatment, there is still a need to explore more effective therapeutic targets and drugs due to the presence of resistance and adverse reactions to biologics. Remetinostat, an HDAC inhibitor, can maintain its potency within the skin with minimal systemic effects, making it a promising topical medication for treating psoriasis. But its effectiveness in treating psoriasis has not been evaluated. In this study, the topical application of remetinostat significantly improved psoriasiform inflammation in an imiquimod-induced mice model by inhibiting CD86 expression of CD11C+I-A/I-E+ dendritic cells (DCs) in the skin. Moreover, remetinostat could dampen the maturation and activation of bone marrow-derived DCs in vitro, as well as the expression of psoriasis-related inflammatory mediators by keratinocytes. In addition, remetinostat could promote keratinocyte differentiation without affecting its proliferation. Our findings demonstrate that remetinostat improves psoriasis by inhibiting the maturation and activation of DCs and the differentiation and inflammation of keratinocytes, which may facilitate the potential application of remetinostat in anti-psoriasis therapy.

Carbohydrate-Lectin Interactions Reprogram Dendritic Cells to Promote Type 1 Anti-Tumor Immunity.

Cancer vaccine development is inhibited by a lack of strategies for directing dendritic cell (DC) induction of effective tumor-specific cellular immunity. Pathogen engagement of DC lectins and toll-like receptors (TLRs) is thought to shape immunity by directing T cell function. Controlling downstream responses, however, remains a major challenge. A critical goal in advancing vaccine development involves the identification of receptors that drive type 1 cellular immunity. The immune system monitors cells for aberrant glycosylation (a sign of a foreign entity), but potent activation occurs when a second signal, such as single-stranded RNA or lipopolysaccharide, is present to activate TLR signaling. To exploit dual signaling, we engineered a glycan-costumed virus-like particle (VLP) vaccine that displays a DC-SIGN-selective aryl mannose ligand and encapsulates TLR7 agonists. These VLPs deliver programmable peptide antigens to induce robust DC activation and type 1 cellular immunity. In contrast, VLPs lacking this critical DC-SIGN ligand promoted DC-mediated humoral immunity, offering limited tumor control. Vaccination with glycan-costumed VLPs generated tumor antigen-specific Th1 CD4+ and CD8+ T cells that infiltrated solid tumors, significantly inhibiting tumor growth in a murine melanoma model. The tailored VLPs also afforded protection against the reintroduction of tumor cells. Thus, DC lectin-driven immune reprogramming, combined with the modular programmability of VLP platforms, provides a promising framework for directing cellular immunity to advance cancer immunotherapies and vaccines.

Enhancing Tumor-Specific immunity with SLdacA: A attenuated Salmonella-mediated c-di-AMP delivery system targeting the STING pathway.

The STING agonist stimulates an anti-tumor immune response by activating T cells, but its limited tumor-targeting specificity poses risks of cytokine storms or autoimmune reactions. Conversely, attenuated Salmonella typhimurium △ppGpp (S.t△ppGpp) exhibits superior tumor-targeting specificity and potent anti-tumor immunogenicity. However, the anti-tumor effects of Salmonella carrying STING agonists remain underexplored. In this study, we engineered a strain called SLdacA, utilizing S.t△ppGpp as a carrier, to produce c-di-AMP. This engineered strain effectively enhances dendritic cell maturation and M1-type macrophage polarization by inducing type I interferon production, thereby recruiting and activating effector T cells against tumor progression. This process is regulated by the STING/type I interferon pathway. Our findings indicate that utilizing S.t△ppGpp as a delivery vehicle for STING agonists holds promise as a strategy for synergistic bacterial-mediated immunotherapy.

In vitro induction of anti­lung cancer immune response by the A549 lung cancer stem cell lysate­sensitized dendritic cell vaccine.

Lung adenocarcinoma is one of the most fatal types of cancer worldwide, with non-small cell lung cancer being the most common subtype. Therefore, there is need for improved treatment approaches. Tumor growth results from the proliferation of a very small number of tumor stem cells, giving rise to the theory of cancer stem cells (CSCs). Lung CSCs are associated with lung cancer development, and although chemotherapy drugs can inhibit the proliferation of lung cancer cells, they have difficulty acting on lung CSCs. Even if the tumor appears to have disappeared after chemotherapy, the presence of a small number of residual tumor stem cells can lead to cancer recurrence and metastasis. Hence, targeting and eliminating lung CSCs is of significant therapeutic importance. In this study, we cultured A549 cells in sphere-forming conditions using B27, EGF, and bFGF, isolated peripheral blood mononuclear cells (PBMCs), and induced and characterized dendritic cells (DCs). We also isolated and expanded T lymphocytes. DC vaccines were prepared using A549 stem cell lysate or A549 cell lysate for sensitization and compared with non-sensitized DC vaccines. The content of IFN-γ in the supernatant of cultures with vaccines and T cells was measured by ELISA. The cytotoxic effects of the vaccines on A549 cells and stem cells were assessed using the Cytotox96 assay, and the impact of the vaccines on A549 cell migration and apoptosis was evaluated using Transwell assays and flow cytometry. DC vaccines sensitized with human lung CSC lysates induced significant in vitro cytotoxic effects on A549 lung cancer cells and CSCs by T lymphocytes, while not producing immune cytotoxic effects on human airway epithelial cells. Moreover, the immune-killing effect induced by DC vaccines sensitized with lung CSC lysates was superior to that of DC vaccines sensitized with lung cancer cells.