DC Respond to Cognate T Cell Interaction in the Antigen-Challenged Lymph Node

Reprogramming dendritic cells through the immunological synapse: A two-way street

Dendritic cells (DCs) bridge innate and adaptive immunity. Their main function is to present antigens to prime T cells and initiate and shape adaptive responses. Antigen presentation takes place through intimate contacts between the two cells, termed immune synapses (IS). During the formation of IS, information travels towards the T-cell side to induce and tune its activation; but it also travels in reverse via engagement of membrane receptors and within extracellular vesicles transferred to the DC. Such reverse information transfer and its consequences on DC fate have been largely neglected. Here, we review the events and effects of IS-mediated antigen presentation on DCs. In addition, we discuss novel technological advancements that enable monitoring DCs interactions with T lymphocytes, the main effects of DCs undergoing productive IS (postsynaptic DCs, or psDCs), and how reverse information transfer could be harnessed to modulate immune responses for therapeutic intervention.

Immune synapse formation promotes lipid peroxidation and MHC-I upregulation in licensed dendritic cells for efficient priming of CD8+ T cells

Antigen cognate dendritic cell (DC)-T cell synaptic interactions drive activation of T cells and instruct DCs. Upon receiving CD4+ T cell help, post-synaptic DCs (psDCs) are licensed to generate CD8+ T cell responses. However, the cellular and molecular mechanisms that enable psDCs licensing remain unclear. Here, we describe that antigen presentation induces an upregulation of MHC-I protein molecules and increased lipid peroxidation on psDCs in vitro and in vivo. We also show that these events mediate DC licensing. In addition, psDC adoptive transfer enhances pathogen-specific CD8+ T responses and protects mice from infection in a CD8+ T cell-dependent manner. Conversely, depletion of psDCs in vivo abrogates antigen-specific CD8+ T cell responses during immunization. Together, our data show that psDCs enable CD8+ T cell responses in vivo during vaccination and reveal crucial molecular events underlying psDC licensing.

The Role of Traditional Chinese Medicine in Cancer Immunotherapy: Current Status and Future Directions

The tumor microenvironment (TME) plays an important role in the development of tumors. Immunoregulatory cells and cytokines facilitate cancer cells to avoid immune surveillance. Overexpression of immune checkpoint molecules such as CTLA-4 and PD-1/PD-L1 inhibits immune function and enables cancer cells to avoid clearance by the immune system. Thus, minimizing tumor immunosuppression could be an important strategy for cancer therapy. Currently, many immune checkpoint-targeted drugs, such as PD-1/PD-L1 inhibitors, have been approved for marketing and have shown unique advantages in the clinical treatment of cancers. The concept of "strengthening resistance to eliminate pathogenic factors" in traditional Chinese medicine (TCM) is consistent with the immunotherapy of cancer. According to previous studies, the role of TCM in tumor immunotherapy is mainly associated with the positive regulation of natural killer cells, CD8/CD4 T cells, dendritic cells, M2 macrophages, interleukin-2, tumor necrosis factor-[Formula: see text], and IFN-[Formula: see text], as well as with the negative regulation of Tregs, myeloid-derived suppressor cells, cancer-associated fibroblasts, PD-1/PD-L1, transforming growth factor-[Formula: see text], and tumor necrosis factor-[Formula: see text]. This paper summarizes the current research on the effect of TCM targeting the TME, and further introduces the research progress on studying the effects of TCM on immune checkpoints. Modern pharmacological studies have demonstrated that TCM can directly or indirectly affect the TME by inhibiting the overexpression of immune checkpoint molecules and enhancing the efficacy of tumor immunotherapy. TCM with immunomodulatory stimulation could be the key factor to achieve benefits from immunotherapy for patients with non-inflammatory, or "cold", tumors.

Cytokine Storm in Acute Viral Respiratory Injury: Role of Qing-Fei-Pai-Du Decoction in Inhibiting the Infiltration of Neutrophils and Macrophages through TAK1/IKK/NF-[Formula: see text]B Pathway

COVID-19 has posed unprecedented challenges to global public health since its outbreak. The Qing-Fei-Pai-Du decoction (QFPDD), a Chinese herbal formula, is widely used in China to treat COVID-19. It exerts an impressive therapeutic effect by inhibiting the progression from mild to critical disease in the clinic. However, the underlying mechanisms remain obscure. Both SARS-CoV-2 and influenza viruses elicit similar pathological processes. Their severe manifestations, such as acute respiratory distress syndrome (ARDS), multiple organ failure (MOF), and viral sepsis, are correlated with the cytokine storm. During flu infection, QFPDD reduced the lung indexes and downregulated the expressions of MCP-1, TNF-[Formula: see text], IL-6, and IL-1[Formula: see text] in broncho-alveolar lavage fluid (BALF), lungs, or serum samples. The infiltration of neutrophils and inflammatory monocytes in lungs was decreased dramatically, and lung injury was ameliorated in QFPDD-treated flu mice. In addition, QFPDD also inhibited the polarization of M1 macrophages and downregulated the expressions of IL-6, TNF-[Formula: see text], MIP-2, MCP-1, and IP-10, while also upregulating the IL-10 expression. The phosphorylated TAK1, IKK[Formula: see text]/[Formula: see text], and I[Formula: see text]B[Formula: see text] and the subsequent translocation of phosphorylated p65 into the nuclei were decreased by QFPDD. These findings indicated that QFPDD reduces the intensity of the cytokine storm by inhibiting the NF-[Formula: see text]B signaling pathway during severe viral infections, thereby providing theoretical and experimental support for its clinical application in respiratory viral infections.

Aptamers as promising nanotheranostic tools in the COVID-19 pandemic era

The emergence of SARS‐COV‐2, the causative agent of new coronavirus disease (COVID‐19) has become a pandemic threat. Early and precise detection of the virus is vital for effective diagnosis and treatment. Various testing kits and assays, including nucleic acid detection methods, antigen tests, serological tests, and enzyme‐linked immunosorbent assay (ELISA), have been implemented or are being explored to detect the virus and/or characterize cellular and antibody responses to the infection. However, these approaches have inherent drawbacks such as nonspecificity, high cost, are characterized by long turnaround times for test results, and can be labor‐intensive. Also, the circulating SARS‐COV‐2 variant of concerns, reduced antibody sensitivity and/or neutralization, and possible antibody‐dependent enhancement (ADE) have warranted the search for alternative potent therapeutics. Aptamers, which are single‐stranded oligonucleotides, generated artificially by SELEX (Evolution of Ligands by Exponential Enrichment) may offer the capacity to generate high‐affinity neutralizers and/or bioprobes for monitoring relevant SARS‐COV‐2 and COVID‐19 biomarkers. This article reviews and discusses the prospects of implementing aptamers for rapid point‐of‐care detection and treatment of SARS‐COV‐2. We highlight other SARS‐COV‐2 targets (N protein, spike protein stem‐helix), SELEX augmented with competition assays and in silico technologies for rapid discovery and isolation of theranostic aptamers against COVID‐19 and future pandemics. It further provides an overview on site‐specific bioconjugation approaches, customizable molecular scaffolding strategies, and nanotechnology platforms to engineer these aptamers into ultrapotent blockers, multivalent therapeutics, and vaccines to boost both humoral and cellular immunity against the virus.

This article is categorized under:

Therapeutic Approaches and Drug Discovery > Emerging Technologies

Diagnostic Tools > Biosensing

Therapeutic Approaches and Drug Discovery > Nanomedicine for Infectious Disease

Therapeutic Approaches and Drug Discovery > Nanomedicine for Respiratory Disease

Dendritic Cells and Their Immunotherapeutic Potential for Treating Type 1 Diabetes

Type 1 diabetes (T1D) results from the destruction of pancreatic beta cells through a process that is primarily mediated by T cells. Emerging evidence suggests that dendritic cells (DCs) play a crucial role in initiating and developing this debilitating disease. DCs are professional antigen-presenting cells with the ability to integrate signals arising from tissue infection or injury that present processed antigens from these sites to naïve T cells in secondary lymphoid organs, thereby triggering naïve T cells to differentiate and modulate adaptive immune responses. Recent advancements in our knowledge of the various subsets of DCs and their cellular structures and methods of orchestration over time have resulted in a better understanding of how the T cell response is shaped. DCs employ various arsenal to maintain their tolerance, including the induction of effector T cell deletion or unresponsiveness and the generation and expansion of regulatory T cell populations. Therapies that suppress the immunogenic effects of dendritic cells by blocking T cell costimulatory pathways and proinflammatory cytokine production are currently being sought. Moreover, new strategies are being developed that can regulate DC differentiation and development and harness the tolerogenic capacity of these cells. Here, in this report, we focus on recent advances in the field of DC immunology and evaluate the prospects of DC-based therapeutic strategies to treat T1D.

Dendritic Cell-Targeted Therapies to Treat Neurological Disorders

Dendritic cells (DCs) are the immune system's highly specialized antigen-presenting cells. When DCs are sluggish and mature, self-antigen presentation results in tolerance; however, when pathogen-associated molecular patterns stimulate mature DCs, antigen presentation results in the development of antigen-specific immunity. DCs have been identified in various vital organs of mammals (e.g., the skin, heart, lungs, intestines, and spleen), but the brain has long been thought to be devoid of DCs in the absence of neuroinflammation. However, neuroinflammation is becoming more recognized as a factor in a variety of brain illnesses. DCs are present in the brain parenchyma in trace amounts under healthy circumstances, but their numbers rise during neuroinflammation. New therapeutics are being developed that can reduce dendritic cell immunogenicity by inhibiting pro-inflammatory cytokine production and T cell co-stimulatory pathways. Additionally, innovative ways of regulating dendritic cell growth and differentiation and harnessing their tolerogenic capability are being explored. Herein, we described the function of dendritic cells in neurological disorders and discussed the potential for future therapeutic techniques that target dendritic cells and dendritic cell-related targets in the treatment of neurological disorders.

Lymph-Node-Targeted Cholesterolized TLR7 Agonist Liposomes Provoke a Safe and Durable Antitumor Response

Toll-like receptor (TLR) agonists as the potent stimulants of an innate immune system hold promises for applications in anticancer immunotherapy. However, most of them are limited in the clinical translation due to the uncontrolled systemic inflammatory response. In the current study, 1V209, a small molecule TLR7 agonist, was conjugated with cholesterol (1V209-Cho) and prepared into liposomes (1V209-Cho-Lip). 1V209-Cho-Lip exerted minimal toxic effects and enhanced the transportation ability in lymph nodes (LNs) compared with 1V209. 1V209-Cho-Lip treatment inhibited tumor progression in CT26 colorectal cancer, 4T1 breast cancer, and Pan02 pancreatic ductal cancer models through inducing effective DC activation and eliciting CD8⁺ T cell responses. Furthermore, 1V209-Cho-Lip induced tumor-specific memory immunity to inhibit cancer recurrence and metastasis. These results indicate that cholesterol conjugation with 1V209 is an effective approach to target lymph nodes and to reduce the adverse effects. This work provides a rational basis for the distribution optimization of TLR agonists for potential clinical use.

The Immune-Related Gene HCST as a Novel Biomarker for the Diagnosis and Prognosis of Clear Cell Renal Cell Carcinoma

Clear cell renal cell carcinoma (ccRCC) is the most common type of kidney tumor worldwide. Analysis of The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) databases showed that the immune-related gene (IRG) hematopoietic cell signal transducer (HCST) could provide guidance for the diagnosis, prognosis, and treatment of ccRCC. The RNA-seq data of ccRCC tissues were extracted from two databases: TCGA (https://www.cancer.gov/about-nci/organization/ccg/research/structural-genomics/tcga) and GEO (https://www.ncbi.nlm.nih.gov/geo/). Corresponding clinical information was downloaded from TCGA. Immune-related gene data were extracted from the IMMPORT website (https://www.immport.org/). Differential analysis with R software (https://www.r-project.org/) was used to obtain a prognosis model of ccRCC IRGs. The differences were combined with the clinical data to assess the usefulness of the HCST as a prognostic biomarker. Based on data obtained from the Oncomine (https://www.oncomine.org/), Human Protein Atlas (https://www.proteinatlas.org/), and PubMed (https://pubmed.ncbi.nlm.nih.gov/) databases, the expression levels of the HCST in ccRCC, clinical-pathological indicators of relevance, and influence on prognosis were analyzed. Regulation of the HCST gene in ccRCC was assessed by gene set enrichment analysis (GSEA). In TCGA/GEO databases, the high HCST expression in tumor tissues was significantly correlated to the TMN stage, tumor grade, invasion depth, and lymphatic metastasis (p < 0.05). The overall survival (OS) of patients with high HCST gene expression was significantly lower than that of patients with low HCST gene expression (p < 0.001). Multivariate Cox regression analysis suggested that the HCST expression level [hazard ratio (HR) = 1.630, 95% confidence interval (CI) = 1.042–2.552], tumor cell grade (HR = 1.829, 95% CI = 1.115–3.001), and distant metastasis (HR = 2.634, 95%, CI = 1.562–4.442) were independent risk factors affecting the OS of ccRCC patients (all, p < 0.05). The GSEA study showed that there was significant enrichment in cell adhesion, tumorigenesis, and immune and inflammatory responses in HCST high expression samples. Hematopoietic cell signal transducer expression was closely associated with the levels of infiltrating immune cells around ccRCC tissues, especially dendritic cells (DCs). In conclusion, the present study suggested that the HCST was interrelated to the clinicopathology and poor prognosis of ccRCC. High HCST expression was also closely correlated with the levels of tumor-infiltrating immune cells, especially DCs.

Dendritic cell vaccine therapy for colorectal cancer

Colorectal cancer (CRC) remains a leading cause of cancer-related deaths in the United States despite an array of available treatment options. Current standard-of-care interventions for this malignancy include surgical resection, chemotherapy, and targeted therapies depending on the disease stage. Specifically, infusion of anti-vascular endothelial growth factor agents in combination with chemotherapy was an important development in improving the survival of patients with advanced colorectal cancer, while also helping give rise to other forms of anti-angiogenic therapies. Yet, one approach by which tumor angiogenesis may be further disrupted is through the administration of a dendritic cell (DC) vaccine targeting tumor-derived blood vessels, leading to cytotoxic immune responses that decrease tumor growth and synergize with other systemic therapies. Early generations of such vaccines exhibited protection against various forms of cancer in pre-clinical models, but clinical results have historically been disappointing. Sipuleucel-T (Provenge®) was the first, and to-date, only dendritic cell-based therapy to receive FDA approval after significantly increasing overall survival in prostate cancer patients. The unparalleled success of Sipuleucel-T has helped revitalize the clinical development of dendritic cell vaccines, which will be examined in this review. We also highlight the promise of these vaccines to instill anti-angiogenic immunity for individuals with advanced colorectal cancer.

An Immunological Approach to the Biocompatibility of Mesoporous SiO2-CaO Nanospheres

Mesoporous bioactive glass nanospheres (NanoMBGs) have high potential for clinical applications. However, the impact of these nanoparticles on the immune system needs to be addressed. In this study, the biocompatibility of SiO₂-CaO NanoMBGs was evaluated on different mouse immune cells, including spleen cells subsets, bone marrow-derived dendritic cells (BMDCs), or cell lines like SR.D10 Th2 CD4⁺ lymphocytes and DC2.4 dendritic cells. Flow cytometry and confocal microscopy show that the nanoparticles were rapidly and efficiently taken up in vitro by T and B lymphocytes or by specialized antigen-presenting cells (APCs) like dendritic cells (DCs). Nanoparticles were not cytotoxic and had no effect on cell viability or proliferation under T-cell (anti-CD3) or B cell (LPS) stimuli. Besides, NanoMBGs did not affect the balance of spleen cell subsets, or the production of intracellular or secreted pro- and anti-inflammatory cytokines (TNF-α, IFN-γ, IL-2, IL-6, IL-10) by activated T, B, and dendritic cells (DC), as determined by flow cytometry and ELISA. T cell activation surface markers (CD25, CD69 and Induced Costimulator, ICOS) were not altered by NanoMBGs. Maturation of BMDCs or DC2.4 cells in vitro was not altered by NanoMBGs, as shown by expression of Major Histocompatibility Complex (MHC) and costimulatory molecules (CD40, CD80, CD86), or IL-6 secretion. The effect of wortmannin and chlorpromazine indicate a role for phosphoinositide 3-kinase (PI3K), actin and clathrin-dependent pathways in NanoMBG internalization. We thus demonstrate that these NanoMBGs are both non-toxic and non-inflammagenic for murine lymphoid cells and myeloid DCs despite their efficient intake by the cells.

Effects of 2,3,7,8-Tetrachlorodibenzo-p-dioxin on T Cell Differentiation in Primary Biliary Cholangitis

Exposure to dioxins, such as 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), is reported to affect the autoimmune system and increase the risk of autoimmune disease. Generally, dioxin exerts its toxicity via aryl hydrocarbon receptor (AhR). Primary biliary cholangitis (PBC) is a chronic autoimmune disease, and its pathogenesis involves the interplay between immune and environmental factors. This study showed the effect of dendritic cells (DCs) activated by TCDD on naïve CD4⁺ T cell differentiation in patients with PBC. CD14⁺ mononuclear cells were isolated from peripheral blood mononuclear cells (PBMCs) of patients with PBC and healthy people by magnetic cell separation and introduced into DCs. Two days after stimulation by TCDD, DCs were cocultured with naïve CD4⁺ T cells in a ratio of 1 : 2 for 3 days. Then, differentiation-related factors for naïve CD4⁺ T cells were detected by real-time fluorescence quantitative polymerase chain reaction, enzyme-linked immunosorbent assay, and flow cytometry. The results showed that TCDD-activated DCs could promote Th1 and Th17 differentiation in patients with PBC. Therefore, this study demonstrated TCDD as an AhR agonist in regulating naïve CD4⁺ T cell differentiation in patients with PBC.

Lymph node-targeted immune-activation mediated by imiquimod-loaded mesoporous polydopamine based-nanocarriers

Toll-like receptor (TLR) agonists are the potent stimulants of innate immune system and hold promises as an adjuvant for anticancer immunotherapy. Unfortunately, most of them are limited by a prompt dissemination, and thus caused "wasted inflammation". Hence, how to restrict their action radius into lymphoid tissues is of great relevance to enhance their efficacy and concomitantly alleviates the side effects. Here, imiquimod (R837), a TLR 7 agonist, was loaded into mesoporous polydopamine (MPDA) nanocarriers with high efficiency. Moreover, its surface was modified by polyvinyl pyrrolidone (PVP) to enhance their lymphatic drainage ability. These nano-adjuvants have obvious advantages in promoting dendritic cell (DC) maturation in comparison to free R837. Moreover, their transportation and retention ability in proximal lymph nodes (LNs) were also confirmed, by which lymphatic drug exposure can be maximized to a great extent. Consequently, effective DC activation and CD8⁺ T cell responses were observed as expected by R837 released in draining LNs. This effect was further enhanced by the presence of endogenous tumor antigens from apoptosis debris induced by MPDA-based photothermal effect, and thus led to the growth inhibition of subcutaneous B16 melanomas. The results demonstrated the great potency against melanoma of the designed PVP-MPDA@R837 nano-adjuvants by combining photothermal conversion property of MPDA with lymphatic-focused immune-activation.

Intravital visualization of interactions of murine Peyer's patch-resident dendritic cells with M cells

The small intestine hosts specialized lymphoid structures, the Peyer's patches, that face the gut lumen and are overlaid with unique epithelial cells, called microfold (M) cells. M cells are considered to constitute an important route for antigen uptake in the mucosal immune system. Here, we used intravital microscopy to define immune cell populations, which are in close contact with M cells and potentially sample antigen. We present live evidence that DCs enter M cell pockets and highlight the abundance of mononuclear phagocytes in these structures. Taking advantage of the respective reporter animals, we focused on classical DCs that express Zbtb46 and analyzed how these cells interact with M cells in steady state and sample antigen for T cell activation in the Peyer's patches following challenge.