Chemokines: a new dendritic cell signal for T cell activation

Hepatocellular Carcinoma and the Multifaceted Relationship with Its Microenvironment: Attacking the Hepatocellular Carcinoma Defensive Fortress

Hepatocellular carcinoma is a malignant tumor that originates from hepatocytes in an inflammatory substrate due to different degrees of liver fibrosis up to cirrhosis. In recent years, there has been growing interest in the role played by the complex interrelationship between hepatocellular carcinoma and its microenvironment, capable of influencing tumourigenesis, neoplastic growth, and its progression or even inhibition. The microenvironment is made up of an intricate network of mesenchymal cells, immune system cells, extracellular matrix, and growth factors, as well as proinflammatory cytokines and translocated bacterial products coming from the intestinal microenvironment via the enterohepatic circulation. The aim of this paper is to review the role of the HCC microenvironment and describe the possible implications in the choice of the most appropriate therapeutic scheme in the prediction of tumor response or resistance to currently applied treatments and in the possible development of future therapeutic perspectives, in order to circumvent resistance and break down the tumor's defensive fort.

Hepatocellular carcinoma immune microenvironment and check point inhibitors-current status

Hepatocellular carcinoma (HCC) is the most common primary tumor of the liver and has a high mortality rate. The Barcelona Clinic Liver Cancer staging system in addition to tumor staging also links the modality of treatment available to a particular stage. The recent description of the tumor microenvironment (TME) in HCC has provided a new concept of immunogenicity within the HCC. Virus-related HCC has been shown to be more immunogenic with higher expression of cytotoxic T lymphocytes and decreased elements for immunosuppression such as regulatory T cells. This immunogenic milieu provides a better response to immunotherapy especially immune checkpoint inhibitors (ICIs). In addition, the recent data on combining locoregional therapies and other strategies may convert the less immunogenic state of the TME towards higher immunogenicity. Therefore, data are emerging on the use of combinations of locoregional therapy and ICIs in unresectable or advanced HCC and has shown better survival outcomes in this difficult population.

Immunity from NK Cell Subsets Is Important for Vaccine-Mediated Protection in HPV+ Cancers

High-risk human papillomaviruses (HPVs) are associated with genital and oral cancers, and the incidence of HPV+ head and neck squamous cell cancers is fast increasing in the USA and worldwide. Survival rates for patients with locally advanced disease are poor after standard-of-care chemoradiation treatment. Identifying the antitumor host immune mediators important for treatment response and designing strategies to promote them are essential. We reported earlier that in a syngeneic immunocompetent preclinical HPV tumor mouse model, intranasal immunization with an HPV peptide therapeutic vaccine containing the combination of aGalCer and CpG-ODN adjuvants (TVAC) promoted clearance of HPV vaginal tumors via induction of a strong cytotoxic T cell response. However, TVAC was insufficient in the clearance of HPV oral tumors. To overcome this deficiency, we tested substituting aGalCer with a clinically relevant adjuvant QS21 (TVQC) and observed sustained, complete regression of over 70% of oral and 80% of vaginal HPV tumors. The TVQC-mediated protection in the oral tumor model correlated with not only strong total and HPV-antigen-specific CD8 T cells, but also natural killer dendritic cells (NKDCs), a novel subset of NK cells expressing the DC marker CD11c. Notably, we observed induction of significantly higher overall innate NK effector responses by TVQC relative to TVAC. Furthermore, in mice treated with TVQC, the frequencies of total and functional CD11c+ NK cell populations were significantly higher than the CD11c- subset, highlighting the importance of the contributions of NKDCs to the vaccine response. These results emphasize the importance of NK-mediated innate immune effector responses in total antitumor immunity to treat HPV+ cancers.

Immune System and Hepatocellular Carcinoma (HCC): New Insights into HCC Progression

According to the WHO's recently released worldwide cancer data for 2020, liver cancer ranks sixth in morbidity and third in mortality among all malignancies. Hepatocellular carcinoma (HCC), the most common kind of liver cancer, accounts approximately for 80% of all primary liver malignancies and is one of the leading causes of death globally. The intractable tumor microenvironment plays an important role in the development and progression of HCC and is one of three major unresolved issues in clinical practice (cancer recurrence, fatal metastasis, and the refractory tumor microenvironment). Despite significant advances, improved molecular and cellular characterization of the tumor microenvironment is still required since it plays an important role in the genesis and progression of HCC. The purpose of this review is to present an overview of the HCC immune microenvironment, distinct cellular constituents, current therapies, and potential immunotherapy methods.

Effects of an aged tissue niche on the immune potency of dendritic cells using simulated microgravity

Microgravity accelerates the aging of various physiological systems, and it is well acknowledged that aged individuals and astronauts both have increased susceptibility to infections and poor response to vaccination. Immunologically, dendritic cells (DCs) are the key players in linking innate and adaptive immune responses. Their distinct and optimized differentiation and maturation phases play a critical role in presenting antigens and mounting effective lymphocyte responses for long-term immunity. Despite their importance, no studies to date have effectively investigated the effects of microgravity on DCs in their native microenvironment, which is primarily located within tissues. Here, we address a significantly outstanding research gap by examining the effects of simulated microgravity via a random positioning machine on both immature and mature DCs cultured in biomimetic collagen hydrogels, a surrogate for tissue matrices. Furthermore, we explored the effects of loose and dense tissues via differences in collagen concentration. Under these various environmental conditions, the DC phenotype was characterized using surface markers, cytokines, function, and transcriptomic profiles. Our data indicate that aged or loose tissue and exposure to RPM-induced simulated microgravity both independently alter the immunogenicity of immature and mature DCs. Interestingly, cells cultured in denser matrices experience fewer effects of simulated microgravity at the transcriptome level. Our findings are a step forward to better facilitate healthier future space travel and enhance our understanding of the aging immune system on Earth.

The liver cancer immune microenvironment: Therapeutic implications for hepatocellular carcinoma

The liver is the sixth most common site of primary cancer in humans and the fourth leading cause of cancer-related death in the world. Hepatocellular carcinoma (HCC) accounts for 90% of liver cancers. HCC is a prevalent disease with a progression that is modulated by the immune system. Half of the patients with HCC receive systemic therapies, traditionally sorafenib or lenvatinib, as a first-line therapy. In the last few years, immune-checkpoint inhibitors (ICIs) have revolutionized cancer therapy and have gained an increased interest in the treatment of HCC. In 2020, the combination of atezolizumab (anti-programmed death-ligand 1) and bevacizumab (anti-vascular endothelial growth factor) improved overall survival over sorafenib, resulting in Food and Drug Administration (FDA) approval as a first-line treatment for patients with advanced HCC. Despite these major advances, a better molecular and cellular characterization of the tumor microenvironment is still needed because it has a crucial role in the development and progression of HCC. Inflamed (hot) and noninflamed (cold) HCC tumors and genomic signatures have been associated with response to ICIs. However, there are no additional biomarkers to guide clinical decision-making. Other immune-targeting strategies, such as adoptive T-cell transfer, vaccination, and virotherapy, are currently under development. This review provides an overview on the HCC immune microenvironment, different cellular players, current available immunotherapies, and potential immunotherapy modalities.

Characterization of immune responses associated with ERAP-1 expression in HSV-induced Behçet's disease mouse model

Behçet's disease (BD) is a chronic multisystem inflammatory disorder. Endoplasmic reticulum aminopeptidase 1 (ERAP1) polymorphism has been reported as a risk factor for BD. However, the immunological role of ERAP1 in BD remains unclear. Therefore, the purpose of this study was to investigate the immunological role of ERAP1 in BD using a mouse model. ERAP1 incomplete expressing mice (ERAP1 hetero, +/-) were generated and inoculated with herpes simplex virus 1 to produce a BD mouse model. In these mice, dendritic cell activation markers and other immune response-related markers were analyzed. Among them, the factor showing a significant difference between ERAP+/- BD mice and WT BD mice was IL-17. In ERAP+/-, BD had significantly different expression levels of CD80, CD11b, Ly6G, RORγt, IFNγ, and IL-17 compared to asymptomatic controls. This study demonstrates ERAP1 defective expressions play an important role in BD development through inappropriate regulation of Th17.

A multiscale mechanistic model of human dendritic cells for in-silico investigation of immune responses and novel therapeutics discovery

Dendritic cells (DCs) are professional antigen-presenting cells (APCs) with the unique ability to mediate inflammatory responses of the immune system. Given the critical role of DCs in shaping immunity, they present an attractive avenue as a therapeutic target to program the immune system and reverse immune disease disorders. To ensure appropriate immune response, DCs utilize intricate and complex molecular and cellular interactions that converge into a seamless phenotype. Computational models open novel frontiers in research by integrating large-scale interaction to interrogate the influence of complex biological behavior across scales. The ability to model large biological networks will likely pave the way to understanding any complex system in more approachable ways. We developed a logical and predictive model of DC function that integrates the heterogeneity of DCs population, APC function, and cell-cell interaction, spanning molecular to population levels. Our logical model consists of 281 components that connect environmental stimuli with various layers of the cell compartments, including the plasma membrane, cytoplasm, and nucleus to represent the dynamic processes within and outside the DC, such as signaling pathways and cell-cell interactions. We also provided three sample use cases to apply the model in the context of studying cell dynamics and disease environments. First, we characterized the DC response to Sars-CoV-2 and influenza co-infection by in-silico experiments and analyzed the activity level of 107 molecules that play a role in this co-infection. The second example presents simulations to predict the crosstalk between DCs and T cells in a cancer microenvironment. Finally, for the third example, we used the Kyoto Encyclopedia of Genes and Genomes enrichment analysis against the model's components to identify 45 diseases and 24 molecular pathways that the DC model can address. This study presents a resource to decode the complex dynamics underlying DC-derived APC communication and provides a platform for researchers to perform in-silico experiments on human DC for vaccine design, drug discovery, and immunotherapies.

Identification and Characterization of Antigenic Properties of Schistosoma japonicum Heat Shock Protein 90α Derived Peptides

It is known that schistosome-derived antigens induce innate and adaptive immune responses that are essential for the formation of hepatic immunopathology. Here, we screened and synthesized four peptides derived from Schistosoma japonicum (S. japonicum) heat shock protein 90α (Sjp90α-1, -2, -3, and -4), which is widely expressed in adults and eggs of the genus S. japonicum and induces remarkable immune reactions. To define the antigenicity of these peptides, we stimulated splenocytes with peptides, and the results showed that only the Sjp90α-1 peptide could predominately induce the activation of dendritic cells (DCs) and macrophages as well as alter the proportion of follicular helper T (Tfh) cells. Next, CD4⁺ T cells were purified and cocultured with mouse bone-marrow-derived DCs (BMDCs) with or without Sjp90α-1 peptide stimulation in vitro, and the results showed that Sjp90α-1-stimulated BMDCs can significantly induce CD4⁺ T-cell differentiation into Tfh cells, while the direct stimulation of CD4⁺ T cells with Sjp90α-1 did not induce Tfh cells, indicating that the Sjp90α-1 peptide promotes Tfh cell differentiation depending on the presence of DCs. Furthermore, we selected and prepared an Sjp90α-1-peptide-based antibody and illustrated that it has excellent reactivity with the immunizing peptide and detects a single band of 29 kDa corresponding to the Sjp90α protein. The immunolocalization results showed that the protein recognized by this Sjp90α-1-peptide-based antibody is present in the mature eggs and the tegument of adults, implying that the parasite-derived peptide has a potential interaction with the host immune system. Finally, we evaluated antipeptide IgG antibodies and revealed a significantly higher level of anti-Sjp90α-1 peptide IgG antibodies in mice 3 weeks after S. japonicum infection. In conclusion, we illustrate that these synthetic peptides warrant further investigation by evaluating their antigen-specific immune response and their ability to efficiently induce Tfh cells. Moreover, they may constitute a potentially helpful method for the laboratory diagnosis of schistosomiasis japonica.

Cross-Activation of Hemichannels/Gap Junctions and Immunoglobulin-Like Domains in Innate–Adaptive Immune Responses

Hemichannels (HCs)/gap junctions (GJs) and immunoglobulin (Ig)-like domain-containing proteins (IGLDCPs) are involved in the innate–adaptive immune response independently. Despite of available evidence demonstrating the importance of HCs/GJs and IGLDCPs in initiating, implementing, and terminating the entire immune response, our understanding of their mutual interactions in immunological function remains rudimentary. IGLDCPs include immune checkpoint molecules of the immunoglobulin family expressed in T and B lymphocytes, most of which are cluster of differentiation (CD) antigens. They also constitute the principal components of the immunological synapse (IS), which is formed on the cell surface, including the phagocytic synapse, T cell synapse, B cell synapse, and astrocytes–neuronal synapse. During the three stages of the immune response, namely innate immunity, innate–adaptive immunity, and adaptive immunity, HCs/GJs and IGLDCPs are cross-activated during the entire process. The present review summarizes the current understanding of HC-released immune signaling factors that influence IGLDCPs in regulating innate–adaptive immunity. ATP-induced “eat me” signals released by HCs, as well as CD31, CD47, and CD46 “don’t eat me” signaling molecules, trigger initiation of innate immunity, which serves to regulate phagocytosis. Additionally, HC-mediated trogocytosis promotes antigen presentation and amplification. Importantly, HC-mediated CD4+ T lymphocyte activation is critical in the transition of the innate immune response to adaptive immunity. HCs also mediate non-specific transcytosis of antibodies produced by mature B lymphocytes, for instance, IgA transcytosis in ovarian cancer cells, which triggers innate immunity. Further understanding of the interplay between HCs/GJs and IGLDCPs would aid in identifying therapeutic targets that regulate the HC–Ig-like domain immune response, thereby providing a viable treatment strategy for immunological diseases. The present review delineates the clinical immunology-related applications of HC–Ig-like domain cross-activation, which would greatly benefit medical professionals and immunological researchers alike. HCs/GJs and IGLDCPs mediate phagocytosis via ATP; “eat me and don’t eat me” signals trigger innate immunity; HC-mediated trogocytosis promotes antigen presentation and amplification in innate–adaptive immunity; HCs also mediate non-specific transcytosis of antibodies produced by mature B lymphocytes in adaptive immunity.

A novel lipidic peptide with potential to promote balanced effector-regulatory T cell responses

T cell-dendritic cell (DC) interactions contribute to reciprocal stimulation leading to DC maturation that results in production of interleukin-12 (IL-12) and interferon-gamma (IFN-γ). Both cytokines have been implicated in autoimmune diseases while being necessary for effective immune responses against foreign antigens. We describe a lipidic peptide, designated IK14004, that modifies crosstalk between T cells and DCs resulting in suppression of IL-12p40/IFN-γ production. T cell production of interleukin-2 (IL-2) and IFN-γ is uncoupled and IL-12p70 production is enhanced. IK14004 induces expression of activating co-receptors in CD8+ T cells and increases the proportion of Foxp3-expressing CD4+ T regulatory cells. The potential for IK14004 to impact on signalling pathways required to achieve a balanced immune response upon stimulation of DCs and T cells is highlighted. This novel compound provides an opportunity to gain further insights into the complexity of T cell-DC interactions relevant to autoimmunity associated with malignancies and may have therapeutic benefit.

The role of dendritic cells in the immune niche of the peritoneum

Dendritic cells (DCs) are professional antigen presenting cells that play an important role in the induction of T cell responses. Different subsets (cDC1s, cDC2s, pDCs, and moDCs) were described based on the expression of different surface markers and functions. In the context of peritoneum, DCs are also a key population cell orchestrating immune responses against pathogens, malignant cells and tissue-damage. Furthermore, they play an important role in the promotion of an anti-inflammatory microenvironment, which is necessary to maintain tolerance and adipocyte homeostasis. The aim of this review is to summarize the current knowledge of the functional and phenotypic features of peritoneal DCs and shed some light on the importance of these cells within this unique cavity and its associated components: the omentum, the mesentery and gut-associated lymphoid tissue (GALT).

From infection to repair: Understanding the workings of our innate immune cells

In a world filled with microbes, some posing a threat to our body, our immune system is key to living a healthy life. The innate immune system is made of various cell types that act to guard our bodies. Unlike the adaptive immune system that has a specific response, our innate immune system encompasses cells that elicit unspecific immune responses, triggered whenever the right signals are detected. Our understanding of immunity started with the concept of our immune system only responding to "nonself" like the pathogens that invade our body. However, over the past few decades, we have learned that the immune system is more than an on/off switch that recognizes nonself. The innate immune system regularly patrols our bodies for pathogens and tissue damage. Our innate immune system not only seeks to resolve infection but also repair tissue injury, through phagocytosing debris and initiating the release of growth factors. Recently, we are starting to see that it is not just recognizing danger, our innate immune system plays a crucial role in repair. Innate immune cells phenotypically change during repair. In the context of severe injury or trauma, our innate immune system is modified quite drastically to help repair, resulting in reduced infection control. Moreover, these changes in immune cell function can be modified by sex as a biological variable. From past to present, in this overview, we provide a summary of the innate immune cells and pathways in infection and tissue repair. This article is categorized under: Immune System Diseases > Molecular and Cellular Physiology.

Development and Characterization of an HCMV Multi-Antigen Therapeutic Vaccine for Glioblastoma Using the UNITE Platform

Glioblastoma multiforme (GBM) is an aggressive form of brain cancer with a median survival of 15 months that has remained unchanged despite advances in the standard of care. GBM cells express human cytomegalovirus (HCMV) proteins, providing a unique opportunity for targeted therapy. We utilized our UNITE (UNiversal Intracellular Targeted Expression) platform to develop a multi-antigen DNA vaccine (ITI-1001) that codes for the HCMV proteins pp65, gB, and IE-1. The UNITE platform involves lysosomal targeting technology, fusing lysosome-associated membrane protein 1 (LAMP1) with target ntigens. We demonstrate evidence of increased antigen presentation by both MHC-I and -II, delivering a robust antigen-specific CD4 and CD8 T-cell response in addition to a strong humoral response. Using a syngeneic orthotopic GBM mouse model, therapeutic treatment with the ITI-1001 vaccine resulted in ~56% survival of tumor-bearing mice. Investigation of the tumor microenvironment showed significant CD4 infiltration as well as enhanced Th1 and cytotoxic CD8 T activation. Regulatory T cells were also upregulated after ITI-1001 vaccination. In addition, tumor burden negatively correlated with activated interferon (IFN)γ+ CD4 T cells, reiterating the importance of CD4 activation in ITI-1001 efficacy and in identifying treatment responders and non-responders. Further characterization of these two groups showed high infiltration of CD3+, CD4+, and CD8+ T cells in responders compared to non-responders. Thus, we show that vaccination with HCMV antigens using the ITI-1001-UNITE platform generates strong cellular and humoral immune responses, triggering significant antitumor activity, leading to enhanced survival in a mouse model of GBM.

A bovine lactoferricin-lactoferrampin-encoding Lactobacillus reuteri CO21 regulates the intestinal mucosal immunity and enhances the protection of piglets against enterotoxigenic Escherichia coli K88 challenge

Enterotoxigenic Escherichia coli (ETEC) is an important cause of diarrhea in human and animal. To determine the mechanism of a bovine lactoferricin-lactoferrampin (LFCA)-encoding Lactobacillus reuteri CO21 (LR-LFCA) to enhance the intestinal mucosal immunity, we used a newborn piglet intestine model to study the intestinal response to ETEC. Pigs were chosen due to the anatomical similarity between the porcine and the human intestine.4-day-old piglets were orally administered with LR-LFCA, LR-con (L. reuteri CO21 transformed with pPG612 plasmid) or phosphate buffered saline (PBS) for three consecutive days, within 21 days after these treatments, we found that LR-LFCA can colonize the intestines of piglets, improve the growth performance, enhance immune response and is beneficial for intestinal health of piglets by improving intestinal barrier function and modulating the composition of gut microbiota. Twenty-one days after, piglets were infected with ETEC K88 for 5 days, we found that oral administration of LR-LFCA to neonatal piglets attenuated ETEC-induced the weight loss of piglets and diarrhea incidence. LR-LFCA decreased the production of inflammatory factors and oxidative stress in intestinal mucosa of ETEC-infected piglets. Additionally, LR-LFCA increased the expression of tight junction proteins in the ileum of ETEC-infected piglets. Using LPS-induced porcine intestinal epithelial cells (IPEC-J2) in vitro, we demonstrated that LR-LFCA-mediated increases in the tight junction proteins might depend on the MLCK pathway; LR-LFCA might increase the anti-inflammatory ability by inhibiting the NF-κB pathway. We also found that LR-LFCA may enhance the antioxidant capacity of piglets by activating the Nrf2/HO-1 pathway. This study demonstrates that LR-LFCA is effective at maintaining intestinal epithelial integrity and host homeostasis as well as at repairing intestinal damage after ETEC infection and is thus a promising alternative therapeutic method for intestinal inflammation.

The Fibronectin-ILT3 Interaction Functions as a Stromal Checkpoint that Suppresses Myeloid Cells

Suppressive myeloid cells inhibit antitumor immunity by preventing T-cell responses. Immunoglobulin-like transcript 3 (ILT3; also known as LILRB4) is highly expressed on tumor-associated myeloid cells and promotes their suppressive phenotype. However, the ligand that engages ILT3 within the tumor microenvironment and renders tumor-associated myeloid cells suppressive is unknown. Using a screening approach, we identified fibronectin as a functional ligand for ILT3. The interaction of fibronectin with ILT3 polarized myeloid cells toward a suppressive state, and these effects were reversed with an ILT3-specific antibody that blocked the interaction of ILT3 with fibronectin. Furthermore, ex vivo treatment of human tumor explants with anti-ILT3 reprogrammed tumor-associated myeloid cells toward a stimulatory phenotype. Thus, the ILT3-fibronectin interaction represents a "stromal checkpoint" through which the extracellular matrix actively suppresses myeloid cells. By blocking this interaction, tumor-associated myeloid cells may acquire a stimulatory phenotype, potentially resulting in increased antitumor T-cell responses.

Conversion of AML-blasts to leukemia-derived dendritic cells (DCleu) in 'DC-culture-media' shifts correlations of released chemokines with antileukemic T-cell reactions

Dendritic cells (DC) and T-cells are mediators of CTL-responses. Autologous (from patients with acute myeloid leukaemia (AML) or myelodysplasia (MDS)) or allogeneic (donor)-T-cells stimulated by DC_leu, gain an efficient lysis of naive blasts, although not in every case. CXCL8, -9, -10, CCL2, -5 and Interleukin (IL-12) were quantified by Cytometric Bead Array (CBA) in supernatants from 5 DC-generating methods and correlated with AML-/MDS-patients' serum-values, DC-/T-cell-interactions/antileukemic T-cell-reactions after mixed lymphocyte culture (MLC) and patients' clinical course. The blast-lytic activity of T-cells stimulated with DC or mononuclear cells (MNC) was quantified in a cytotoxicity assay. Despite great variations of chemokine-levels, correlations with post-stimulation (after stimulating T-cells with DC in MLC) improved antileukemic T-cell activity were seen: higher released chemokine-values correlated with improved T-cells' antileukemic activity (compared to stimulation with blast-containing MNC) - whereas with respect to the corresponding serum values higher CXCL8-, -9-, and -10- but lower CCL5- and -2-release correlated with improved antileukemic activity of DC-stimulated (vs. blast-stimulated) T-cells. In DC-culture supernatants higher chemokine-values correlated with post-stimulation improved antileukemic T-cell reactivity, whereas higher serum-values of CXCL8, -9, and -10 but lower serum-values of CCL5 and -2 correlated with post-stimulation improved antileukemic T-cell-reactivity. In a context of 'DC'-stimulation (vs serum) this might point to a change of (CCL5 and -2-associated) functionality from a more 'inflammatory' or 'tumor-promoting' to a more 'antitumor'-reactive functionality. This knowledge could contribute to develop immune-modifying strategies that promote antileukemic (adaptive) immune-responses.

Next-Generation Immunotherapies to Improve Anticancer Immunity

Checkpoint inhibitors are widely used immunotherapies for advanced cancer. Nonetheless, checkpoint inhibitors have a relatively low response rate, work in a limited range of cancers, and have some unignorable side effects. Checkpoint inhibitors aim to reinvigorate exhausted or suppressed T cells in the tumor microenvironment (TME). However, the TME contains various other immune cell subsets that interact to determine the fate of cytotoxic T cells. Activation of cytotoxic T cells is initiated by antigen cross-presentation of dendritic cells. Dendritic cells could also release chemokines and cytokines to recruit and foster T cells. B cells, another type of antigen-presenting cell, also foster T cells and can produce tumor-specific antibodies. Neutrophils, a granulocyte cell subset in the TME, impede the proliferation and activation of T cells. The TME also consists of cytotoxic innate natural killer cells, which kill tumor cells efficiently. Natural killer cells can eradicate major histocompatibility complex I-negative tumor cells, which escape cytotoxic T cell–mediated destruction. A thorough understanding of the immune mechanism of the TME, as reviewed here, will lead to further development of more powerful therapeutic strategies. We have also reviewed the clinical outcomes of patients treated with drugs targeting these immune cells to identify strategies for improvement and possible immunotherapy combinations.

DNA aptamer-based rolling circle amplification product as a novel immunological adjuvant

Several agonists to CD40 have shown to induce acquired immune responses. Here, we developed and evaluated the rolling circle amplification (RCA) products that are based on anti-CD40 DNA aptamers as a novel vaccine adjuvant. First, we developed DNA aptamers with specific binding affinity to chicken CD40 extra domain (chCD40ED). Next, we prepared the RCA products that consist of these aptamers to increase the spanning space and overall binding affinity to chCD40ED. Using 8 DNA aptamer candidates, 4 aptamer-based RCA products (aptamer RCAs) were generated, each consisting of two distinct aptamers. We demonstrated that all 4 aptamer RCAs significantly induced the signal transduction in chicken HD11 macrophage cell line (p < 0.05). Finally, we conjugated one of the aptamer RCAs (Aptamer RCA II) to M2e epitope peptide of influenza virus as a model hapten, and the immune complex was injected to chickens. Aptamer RCA II stimulated anti-M2e IgG antibody production to the level significantly higher as compared to the control (M2e epitope alone; p < 0.05). The results of our work suggest that aptamer RCA is a novel platform to boost the efficacy of vaccines, which might find broad applications to other antigens beyond M2e epitope evaluated in this study using chicken infection model.

COVID-19: The Emerging Immunopathological Determinants for Recovery or Death

Hyperactivation of the host immune system during infection by SARS-CoV-2 is the leading cause of death in COVID-19 patients. It is also evident that patients who develop mild/moderate symptoms and successfully recover display functional and well-regulated immune response. Whereas a delayed initial interferon response is associated with severe disease outcome and can be the tipping point towards immunopathological deterioration, often preceding death in COVID-19 patients. Further, adaptive immune response during COVID-19 is heterogeneous and poorly understood. At the same time, some studies suggest activated T and B cell response in severe and critically ill patients and the presence of SARS-CoV2-specific antibodies. Thus, understanding this problem and the underlying molecular pathways implicated in host immune function/dysfunction is imperative to devise effective therapeutic interventions. In this comprehensive review, we discuss the emerging immunopathological determinants and the mechanism of virus evasion by the host cell immune system. Using the knowledge gained from previous respiratory viruses and the emerging clinical and molecular findings on SARS-CoV-2, we have tried to provide a holistic understanding of the host innate and adaptive immune response that may determine disease outcome. Considering the critical role of the adaptive immune system during the viral clearance, we have presented the molecular insights of the plausible mechanisms involved in impaired T cell function/dysfunction during various stages of COVID-19.

Dynamic and Differential Expression of Duplicated Cxcr4/Cxcl12 Genes Facilitates Antiviral Response in Hexaploid Gibel Carp

Chemokine receptor cxcr4 and its ligand cxcl12 have evolved two paralogs in the teleost lineage. In this study, we have identified four duplicated cxcr4 and cxcl12 genes from hexaploid gibel carp, Carassius gibelio, respectively. Cgcxcr4bs and Cgcxcl12as were dynamically and differentially expressed in immune-related tissues, and significantly up-regulated in head kidney and spleen after crucian carp herpesvirus (CaHV) infection. Blocking Cxcr4/Cxcl12 axis by injecting AMD3100 brought more severe bleeding symptom and lower survival rate in CaHV-infected fish. AMD3100 treatment also suppressed the up-regulation of key antiviral genes in head kidney and spleen, and resulted in more acute replication of CaHV in vivo. Consistently, the similar suppression of up-regulated expression of key antiviral genes were also observed in CAB cells treated by AMD3100 after poly(I:C) stimulation. Finally, MAPK3 and JAK/STAT were identified as the possible pathways that CgCxcr4s and CgCxcl12s participate in to promote the antiviral response in vitro.

Intranasal Therapeutic Peptide Vaccine Promotes Efficient Induction and Trafficking of Cytotoxic T Cell Response for the Clearance of HPV Vaginal Tumors

Human papillomavirus (HPV)-induced cancers continue to affect millions of women around the world, and the five year survival rate under the current standard of care for these cancers is less than 60% in some demographics. Therefore there is still an unmet need to develop an effective therapy that can be easily administered to treat established HPV cervical cancer lesions. We sought to investigate the potential of an intranasal HPV peptide therapeutic vaccine incorporating the combination of α-Galactosylceramide (α-GalCer) and CpG-ODN adjuvants (TVAC) against established HPV genital tumors in a syngeneic C57BL/6J mouse model. We obtained evidence to show that TVAC, delivered by the mucosal intranasal route, induced high frequencies of antigen-specific CD8 T cells concurrent with significant reduction in the immunosuppressive regulatory T cells and myeloid derived suppressor cells in the tumor microenvironment (TME), correlating with sustained elimination of established HPV genital tumors in over 85% of mice. Inclusion of both the adjuvants in the vaccine was necessary for significant increase of antigen-specific CD8 T cells to the tumor and antitumor efficacy because vaccination incorporating either adjuvant alone was inefficient. These results strongly support the utility of the TVAC administered by needle-free intranasal route as a safe and effective strategy for the treatment of established genital HPV tumors.

The CD4+ T Cell Response to Human Cytomegalovirus in Healthy and Immunocompromised People

While CD8+ T cells specific for human cytomegalovirus (HCMV) have been extensively studied in both healthy HCMV seropositive carriers and patients undergoing immunosuppression, studies on the CD4+ T cell response to HCMV had lagged behind. However, over the last few years there has been a significant advance in our understanding of the importance and contribution that CMV-specific CD4+ T cells make, not only to anti-viral immunity but also in the potential maintenance of latently infected cells. During primary infection with HCMV in adults, CD4+ T cells are important for the resolution of symptomatic disease, while persistent shedding of HCMV into urine and saliva is associated with a lack of HCMV specific CD4+ T cell response in young children. In immunosuppressed solid organ transplant recipients, a delayed appearance of HCMV-specific CD4+ T cells is associated with prolonged viremia and more severe clinical disease, while in haematopoietic stem cell transplant recipients, it has been suggested that HCMV-specific CD4+ T cells are required for HCMV-specific CD8+ T cells to exert their anti-viral effects. In addition, adoptive T-cell immunotherapy in transplant patients has shown that the presence of HCMV-specific CD4+ T cells is required for the maintenance of HCMV-specific CD8+ T cells. HCMV is a paradigm for immune evasion. The presence of viral genes that down-regulate MHC class II molecules and the expression of viral IL-10 both limit antigen presentation to CD4+ T cells, underlining the important role that this T cell subset has in antiviral immunity. This review will discuss the antigen specificity, effector function, phenotype and direct anti-viral properties of HCMV specific CD4+ T cells, as well as reviewing our understanding of the importance of this T cell subset in primary infection and long-term carriage in healthy individuals. In addition, their role and importance in congenital HCMV infection and during immunosuppression in both solid organ and haemopoietic stem cell transplantation is considered.

Serum Chemokine-release Profiles in AML-patients Might Contribute to Predict the Clinical Course of the Disease

In cancer or hematologic disorders, chemokines act as growth- or survival factors, regulating hematopoiesis and angiogenesis, determining metastatic spread and controlling leukocyte infiltration into tumors to inhibit antitumor immune responses. The aim was to quantify the release of CXCL8, -9, -10, CCL2, -5, and IL-12 in AML/MDS-pts' serum by cytometric bead array and to correlate data with clinical subtypes and courses. Minimal differences in serum-levels subdivided into various groups (e.g. age groups, FAB-types, blast-proportions, cytogenetic-risk-groups) were seen, but higher release of CXCL8, -9, -10 and lower release of CCL2 and -5 tendentially correlated with more favorable subtypes (<50 years of age, <80% blasts in PB). Comparing different stages of the disease higher CCL5-release in persisting disease and a significantly higher CCL2-release at relapse were found compared to first diagnosis - pointing to a change of 'disease activity' on a chemokine level. Correlations with later on achieved response to immunotherapy and occurrence of GVHD were seen: Higher values of CXCL8, -9, -10 and CCL2 and lower CCL5-values correlated with achieved response to immunotherapy. Predictive cut-off-values were evaluated separating the groups in 'responders' and 'non-responders'. Higher levels of CCL2 and -5 but lower levels of CXCL8, -9, -10 correlated with occurrence of GVHD. We conclude, that in AML-pts' serum higher values of CXCL8, -9, -10 and lower values of CCL5 and in part of CCL2 correlate with more favorable subtypes and improved antitumor'-reactive function. This knowledge can contribute to develop immune-modifying strategies that promote antileukemic adaptive immune responses.

Molecular cloning, characterization and expression analysis of MHCI and chemokines CXCR3 and CXCR4 gene from freshwater carp, Catla catla

The immune system with large number of molecules protects the host against a plethora of continuously evolving microbes. Major histocompatibility complex (MHC) molecules serve as cardinal elements of the adaptive immune system responsible for the activation of the adaptive immunity in the host. The present study reports MHCI molecule in freshwater carp, Catla catla, and its differential expression in immunologically relevant tissues post-infection with Gram-negative and Gram-positive bacteria. The MHCI sequence of C. catla had 502 bp nucleotides encoding putative 146 amino acids. The phylogenetic analysis exhibited its evolutionary conservation within the Cyprinidae family and formed a different clade with the higher vertebrates. Simultaneously, CXCR3 and CXCR4 chemokines were cloned and characterized for their expression in infected tissues. Analysis of immunologically relevant tissues of the infected fish exhibited an increase of MHCI gene expression and the down-regulation of CXCR3 and CXCR4 chemokines, indicating a tricky interaction between the innate and adaptive immune system. It was found that intestine, skin and spleen played a crucial role in the contribution of the defense activity which instigated the self-immunity. These immune activities can provide useful information to understand the interaction of self and non-self- immune system in freshwater fish, Catla catla.

Unfolded Protein Response (UPR) in Survival, Dormancy, Immunosuppression, Metastasis, and Treatments of Cancer Cells

The endoplasmic reticulum (ER) has diverse functions, and especially misfolded protein modification is in the focus of this review paper. With a highly regulatory mechanism, called unfolded protein response (UPR), it protects cells from the accumulation of misfolded proteins. Nevertheless, not only does UPR modify improper proteins, but it also degrades proteins that are unable to recover. Three pathways of UPR, namely PERK, IRE-1, and ATF6, have a significant role in regulating stress-induced physiological responses in cells. The dysregulated UPR may be involved in diseases, such as atherosclerosis, heart diseases, amyotrophic lateral sclerosis (ALS), and cancer. Here, we discuss the relation between UPR and cancer, considering several aspects including survival, dormancy, immunosuppression, angiogenesis, and metastasis of cancer cells. Although several moderate adversities can subject cancer cells to a hostile environment, UPR can ensure their survival. Excessive unfavorable conditions, such as overloading with misfolded proteins and nutrient deprivation, tend to trigger cancer cell death signaling. Regarding dormancy and immunosuppression, cancer cells can survive chemotherapies and acquire drug resistance through dormancy and immunosuppression. Cancer cells can also regulate the downstream of UPR to modulate angiogenesis and promote metastasis. In the end, regulating UPR through different molecular mechanisms may provide promising anticancer treatment options by suppressing cancer proliferation and progression.

Wnt1 silences chemokine genes in dendritic cells and induces adaptive immune resistance in lung adenocarcinoma

Lung adenocarcinoma (LUAD)-derived Wnts increase cancer cell proliferative/stemness potential, but whether they impact the immune microenvironment is unknown. Here we show that LUAD cells use paracrine Wnt1 signaling to induce immune resistance. In TCGA, Wnt1 correlates strongly with tolerogenic genes. In another LUAD cohort, Wnt1 inversely associates with T cell abundance. Altering Wnt1 expression profoundly affects growth of murine lung adenocarcinomas and this is dependent on conventional dendritic cells (cDCs) and T cells. Mechanistically, Wnt1 leads to transcriptional silencing of CC/CXC chemokines in cDCs, T cell exclusion and cross-tolerance. Wnt-target genes are up-regulated in human intratumoral cDCs and decrease upon silencing Wnt1, accompanied by enhanced T cell cytotoxicity. siWnt1-nanoparticles given as single therapy or part of combinatorial immunotherapies act at both arms of the cancer-immune ecosystem to halt tumor growth. Collectively, our studies show that Wnt1 induces immunologically cold tumors through cDCs and highlight its immunotherapeutic targeting.

CD11c-Positive Dendritic Cells in Triple-negative Breast Cancer

BACKGROUND

Tumor-infiltrating lymphocytes (TILs) and tertiary lymphoid structures (TLSs) are prognostic markers in triple-negative breast cancer (TNBC). Our study analyzed the relationship between cluster of differentiation (CD)11c-positive dendritic cells (DCs) and TILs and TLSs to elucidate mechanisms of TIL influx.

MATERIALS AND METHODS

Immunohistochemical staining for CD4, CD8, and CD11c in tissue microarrays from 681 patients with TNBC was performed. The proportions of TILs and TLSs were reviewed. Two additional TNBC gene expression datasets were used.

RESULTS

CD11c expression showed a significantly positive correlation with the level of TILs and the number of CD4⁺ and CD8⁺ T-cells, as well as an abundance of TLSs. CD11C gene expression was also significantly correlated with expression of CD4, CD8, and genes related to TLSs in both datasets.

CONCLUSION

We demonstrated a strong correlation of CD11c expression, which represents DCs, with TILs and TLSs in TNBC. Further investigation is warranted to identify therapeutic modalities that facilitate recruitment and activation of DCs.

Chemo-immunotherapy improves long-term survival in a preclinical model of MMR-D-related cancer

BACKGROUND

Mismatch Repair Deficiency (MMR-D)-related tumors are highly immunogenic and constitute ideal vaccination targets. In a proof-of-concept study delayed tumorigenesis and prolonged survival has been shown in a clinically-relevant mouse model for MMR-D-related diseases (=MLH1 knock out mice). To refine this approach, vaccination was combined with immune modulatory low-dose chemotherapy to polarize immune regulatory subtypes.

METHODS

Mice (prophylactic: 8-10 weeks; therapeutic: > 36 weeks) received a single injection of cyclophosphamide (CPX, 120 mg/kg bw, i.p.) or gemcitabine (GEM, 100 mg/kg bw, i.p.) prior to vaccination (lysate of a gastrointestinal tumor allograft, 10 mg/kg bw, n = 9 mice/group). The vaccine was given repetitively (10 mg/kg bw, s.c., 4 x / once a week, followed by monthly boosts) until tumor formation or progression. Tumor growth ([18F] FDG PET/CT imaging) and immune responses were monitored (flow cytometry, IFNγ ELISpot). The microenvironment was analyzed by immunofluorescence.

RESULTS

Prophylactic application of GEM + lysate delayed tumorigenesis compared to lysate monotherapy and CPX-pre-treatment (median time of onset: 53 vs. 47 vs. 48 weeks). 33% of mice even remained tumor-free until the experimental endpoint (= 65 weeks). This was accompanied by long-term effect on cytokine plasma levels; splenic myeloid derived suppressor cells (MDSC) as well as regulatory T cell numbers. Assessment of tumor microenvironment from GEM + lysate treated mice revealed low numbers of MDSCs, but enhanced T cell infiltration, in some cases co-expressing PD-L1. Therapeutic chemo-immunotherapy (GEM + lysate) had minor impact on overall survival (median time: 12 (GEM + lysate) vs. 11.5 (lysate) vs. 3 weeks (control)), but induced complete remission in one case. Dendritic and T cell infiltrates increased in both treatment groups. Reactive T cells specifically recognized MLH1-/- tumor cells in IFNγ ELISpot, but lacked response towards NK cell targets YAC-1.

CONCLUSIONS

Combined chemo-immunotherapy impairs tumor onset and growth likely attributable to modulation of immune responses. Depleting or 're-educating' immunosuppressive cell types, such as MDSC, may help moving a step closer to combat cancer.

Selective Effects of mTOR Inhibitor Sirolimus on Naïve and CMV-Specific T Cells Extending Its Applicable Range Beyond Immunosuppression

Cytomegalovirus (CMV) infection/reactivation remains among the most important complications of immunosuppression after transplantation. However, recent clinical observations indicate that mammalian target of rapamycin (mTOR) inhibition with sirolimus may improve the outcome of CMV complications. Underlying mechanisms of this observation, particularly the effect of sirolimus on naïve- and CMV-specific cytotoxic CD8⁺ T-cell (CMV-CTL) functionality is still undiscovered. Here, the influence of sirolimus on naïve and memory CMV-CTLs was determined by CD3/CD28 crosslinking and alloreactivity assays. After stimulating CMV-CTL with HLA-A^*02:01-restricted CMVpp65-peptide loaded artificial antigen-presenting cells (aAPCs), we measured the effect of sirolimus on T-cell proliferation, phenotype, and functionality. Sirolimus significantly improved CMV-specific effector memory T-cell function and negatively influenced naïve T cells. This unique mechanism of action was further characterized by increased secretion of interferon-gamma (IFN-γ), granzyme B (GzB) and enhanced target-cell-dependent cytotoxic capacity of activated CMV-CTLs. Next-generation-sequencing (NGS) was applied to monitor T-cell receptor (TCR)-repertoire dynamics and to verify, that the increased functionality was not related to sirolimus-resistant CTL-clones. Instead, modulation of environmental cues during CMV-CTL development via IL-2 receptor (IL-2R)-driven signal transducer and activator of transcription-5 (STAT-5) signaling under mTOR inhibition allowed fine-tuning of T-cell programming for enhanced antiviral response with stable TCR-repertoire dynamics. We show for the first time that sirolimus acts selectively on human naïve and memory T cells and improves CMV-specific T-cell function via modulation of the environmental milieu. The data emphasize the importance to extend immune monitoring including cytokine levels and T-cell functionality which will help to identify patients who may benefit from individually tailored immunosuppression.

Targeting myeloid derived suppressor cells with all-trans retinoic acid is highly time-dependent in therapeutic tumor vaccination

Tumor immune escape is a critical problem which frequently accounts for the failure of therapeutic tumor vaccines. Among the most potent suppressors of tumor immunity are myeloid derived suppressor cells (MDSCs). MDSCs can be targeted by all-trans-retinoic-acid (atRA), which reduced their numbers and increased response rates in several vaccination studies. However, not much is known about the optimal administration interval between atRA and the vaccine as well as about its mode of action. Here we demonstrate in 2 different murine tumor models that mice unresponsive to a therapeutic vaccine harbored higher MDSC numbers than did responders. Application of atRA overcame MDSC-mediated immunosuppression and restored tumor control. Importantly, atRA was protective only when administered 3 d after vaccination (delayed treatment), whereas simultaneous administration even decreased the anti-tumor immune response and reduced survival. When analyzing the underlying mechanisms, we found that delayed, but not simultaneous atRA treatment with vaccination abrogated the suppressive capacity in monocytic MDSCs and instead caused them to upregulate MHC-class-II. Consistently, MDSCs from patients with colorectal carcinoma also failed to upregulate HLA-DR after ex vivo treatment with TLR-ligation. Overall, we demonstrate that atRA can convert non-responders to responders to vaccination by suppressing MDSCs function and not only by reducing their number. Moreover, we identify a novel, strictly time-dependent mode of action of atRA to be considered during immunotherapeutic protocols in the future.

Inflammation enhances the vaccination potential of CD40-activated B cells in mice

Vaccination with antigen-pulsed CD40-activated B (CD40-B) cells can efficiently lead to the in vivo differentiation of naive CD8⁺ T cells into fully functional effectors. In contrast to bone marrow-derived dendritic cell (BMDC) vaccination, CD40-B cell priming does not allow for memory CD8⁺ T-cell generation but the reason for this deficiency is unknown. Here, we show that compared to BMDCs, murine CD40-B cells induce lower expression of several genes regulated by T-cell receptor signaling, costimulation, and inflammation (signals 1-3) in mouse T cells. The reduced provision of signals 1 and 2 by CD40-B cells can be explained by a reduction in the quality and duration of the interactions with naive CD8⁺ T cells as compared to BMDCs. Furthermore, CD40-B cells produce less inflammatory mediators, such as IL-12 and type I interferon, and increasing inflammation by coadministration of polyriboinosinic-polyribocytidylic acid with CD40-B-cell immunization allowed for the generation of long-lived and functional CD8⁺ memory T cells. In conclusion, it is possible to manipulate CD40-B-cell vaccination to promote the formation of long-lived functional CD8⁺ memory T cells, a key step before translating the use of CD40-B cells for therapeutic vaccination.

Granulocyte colony-stimulating factor impairs CD8(+) T cell functionality by interfering with central activation elements

Besides mobilizing stem cells into the periphery, granulocyte colony-stimulating factor (G-CSF) has been shown to influence various types of innate and adaptive immune cells. For example, it impairs the effector function of cytotoxic T lymphocytes (CTLs). It is assumed that this effect is mediated indirectly by monocytes, regulatory T cells and immunomodulatory cytokines influenced by G-CSF. In this study, isolated G-CSF-treated CD8(+) T cells were stimulated antigen-dependently with peptide-major histocompatibility complex (pMHC)-coupled artificial antigen-presenting cells (aAPCs) or stimulated antigen-independently with anti-CD3/CD28 stimulator beads. By measuring the changes in interferon (IFN)-γ and granzyme B expression at the mRNA and protein level, we showed for the first time that G-CSF has a direct effect on CD8(+) CTLs, which was confirmed based on the reduced production of IFN-γ and granzyme B by the cytotoxic T cell line TALL-104 after G-CSF treatment. By investigating further elements affected by G-CSF in CTLs from stem cell donors and untreated controls, we found a decreased phosphorylation of extracellular-regulated kinase (ERK)1/2, lymphocyte-specific protein tyrosine kinase (Lck) and CD3ζ after G-CSF treatment. Additionally, miRNA-155 and activation marker expression levels were reduced. In summary, our results show that G-CSF directly influences the effector function of cytotoxic CD8(+) T cells and affects various elements of T cell activation.

Immunological principles regulating immunomodulation with biomaterials

The immune system has evolved to recognize and eliminate pathogens; this recognition relies on the identification of structural molecular patterns within unique tissue microenvironments. Therefore, bioengineers can harness these immunological cues to design materials that modulate innate and adaptive immunity in a controlled manner. This review acts as an immunology primer by focusing on the basic molecular and cellular immunology principles governing immunomodulation with biomaterials.