Human in vivo-generated monocyte-derived dendritic cells and macrophages cross-present antigens through a vacuolar pathway

Alveolar macrophages instruct CD8+ T cell expansion by antigen cross-presentation in lung

Lung CD8⁺ memory T cells play central roles in protective immunity to respiratory viruses, such as influenza A virus (IAV). Here, we find that alveolar macrophages (AMs) function as antigen-presenting cells that support the expansion of lung CD8⁺ memory T cells. Intranasal antigen administration to mice subcutaneously immunized with antigen results in a rapid expansion of antigen-specific CD8⁺ T cells in the lung, which is dependent on antigen cross-presentation by AMs. AMs highly express interleukin-18 (IL-18), which mediates subsequent formation of CD103⁺CD8⁺ resident memory T (T_RM) cells in the lung. In a mouse model of IAV infection, AMs are required for expansion of virus-specific CD8⁺ T cells and CD103⁺CD8⁺ T_RM cells and inhibiting virus replication in the lungs during secondary infection. These results suggest that AMs instruct a rapid expansion of antigen-specific CD8⁺ T cells in lung, which protect the host from respiratory virus infection.

Longitudinal transcriptional analysis of peripheral blood leukocytes in COVID-19 convalescent donors

BACKGROUND

SARS-CoV2 can induce a strong host immune response. Many studies have evaluated antibody response following SARS-CoV2 infections. This study investigated the immune response and T cell receptor diversity in people who had recovered from SARS-CoV2 infection (COVID-19).

METHODS

Using the nCounter platform, we compared transcriptomic profiles of 162 COVID-19 convalescent donors (CCD) and 40 healthy donors (HD). 69 of the 162 CCDs had two or more time points sampled.

RESULTS

After eliminating the effects of demographic factors, we found extensive differential gene expression up to 241 days into the convalescent period. The differentially expressed genes were involved in several pathways, including virus-host interaction, interleukin and JAK-STAT signaling, T-cell co-stimulation, and immune exhaustion. A subset of 21 CCD samples was found to be highly "perturbed," characterized by overexpression of PLAU, IL1B, NFKB1, PLEK, LCP2, IRF3, MTOR, IL18BP, RACK1, TGFB1, and others. In addition, one of the clusters, P1 (n = 8) CCD samples, showed enhanced TCR diversity in 7 VJ pairs (TRAV9.1_TCRVA_014.1, TRBV6.8_TCRVB_016.1, TRAV7_TCRVA_008.1, TRGV9_ENST00000444775.1, TRAV18_TCRVA_026.1, TRGV4_ENST00000390345.1, TRAV11_TCRVA_017.1). Multiplexed cytokine analysis revealed anomalies in SCF, SCGF-b, and MCP-1 expression in this subset.

CONCLUSIONS

Persistent alterations in inflammatory pathways and T-cell activation/exhaustion markers for months after active infection may help shed light on the pathophysiology of a prolonged post-viral syndrome observed following recovery from COVID-19 infection. Future studies may inform the ability to identify druggable targets involving these pathways to mitigate the long-term effects of COVID-19 infection.

TRIAL REGISTRATION

https://clinicaltrials.gov/ct2/show/NCT04360278 Registered April 24, 2020.

Human dendritic cell subsets: An updated view of their ontogeny and functional specialization

Human DCs have been divided into several subsets based on their phenotype and ontogeny. Recent high throughput single-cell methods have revealed additional heterogeneity within human DC subsets, and new subpopulations have been proposed. In this review, we provide an updated view of the human DC subsets and of their ontogeny supported by recent clinical studies . We also summarize their main characteristics including their functional specialization.

Metabolic guidance and stress in tumors modulate antigen-presenting cells

Successful antitumor immunity largely relies on efficient T cell priming by antigen-presenting cells (APCs); however, the capacity of APCs is found to be defective in many cancers. Metabolically reprogrammed cancer cells support the energetic and biosynthetic demands of their high proliferation rates by exploiting nutrients available in the tumor microenvironment (TME), which in turn limits proper metabolic reprogramming of APCs during recruitment, differentiation, activation and antigen presentation. Furthermore, some metabolites generated by the TME are unfavorable to antitumor immunity. This review summarizes recent studies on the metabolic features of APCs and their functionality in the TME. Particularly, we will describe how APCs respond to altered TME and how metabolic byproducts from cancer and immunomodulatory cells affect APCs. Finally, we introduce the current status of APC-oriented research and clinical trials targeting metabolic features to boost efficient immunotherapy.

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

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

Mast Cells and Dendritic Cells as Cellular Immune Checkpoints in Immunotherapy of Solid Tumors

The immune checkpoint inhibitors have revolutionized cancer immunotherapy. These inhibitors are game changers in many cancers and for many patients, sometimes show unprecedented therapeutic efficacy. However, their therapeutic efficacy is largely limited in many solid tumors where the tumor-controlled immune microenvironment prevents the immune system from efficiently reaching, recognizing, and eliminating cancer cells. The tumor immune microenvironment is largely orchestrated by immune cells through which tumors gain resistance against the immune system. Among these cells are mast cells and dendritic cells. Both cell types possess enormous capabilities to shape the immune microenvironment. These capabilities stage these cells as cellular checkpoints in the immune microenvironment. Regaining control over these cells in the tumor microenvironment can open new avenues for breaking the resistance of solid tumors to immunotherapy. In this review, we will discuss mast cells and dendritic cells in the context of solid tumors and how these immune cells can, alone or in cooperation, modulate the solid tumor resistance to the immune system. We will also discuss how this modulation could be used in novel immunotherapeutic modalities to weaken the solid tumor resistance to the immune system. This weakening could then help other immunotherapeutic modalities engage against these tumors more efficiently.

An immunotherapy response prediction model derived from proliferative CD4+ T cells and antigen-presenting monocytes in ccRCC

Most patients with clear cell renal cell carcinoma (ccRCC) have an impaired response to immune checkpoint blockade (ICB) therapy. Few biomarkers can predict responsiveness, and there is insufficient evidence to extend them to ccRCC clinical use. To explore subtypes and signatures of immunocytes with good predictive performance for ICB outcomes in the ccRCC context, we reanalyzed two ccRCC single-cell RNA sequencing (scRNA-seq) datasets from patients receiving ICB treatment. A subtype of proliferative CD4⁺ T cells and regulatory T cells and a subtype of antigen-presenting monocytes that have good predictive capability and are correlated with ICB outcomes were identified. These findings were corroborated in independent ccRCC ICB pretreatment bulk RNA-seq datasets. By incorporating the cluster-specific marker genes of these three immunocyte subtypes, we developed a prediction model, which reached an AUC of 93% for the CheckMate cohort (172 samples). Our study shows that the ICB response prediction model can serve as a valuable clinical decision-making tool for guiding ICB treatment of ccRCC patients.

Dendritic Cell Vaccines: A Promising Approach in the Fight against Ovarian Cancer

Simple Summary

With an overall 5-year survival of only 20% for advanced-stage ovarian cancer patients, enduring and effective therapies are a highly unmet clinical need. Current standard-of-care therapies are able to improve progression-free survival; however, patients still relapse. Moreover, immunotherapy has not resulted in clear patient benefits so far. In this situation, dendritic cell vaccines can serve as a potential therapeutic addition against ovarian cancer. In the current review, we provide an overview of the different dendritic cell subsets and the roles they play in ovarian cancer. We focus on the advancements in dendritic cell vaccination against ovarian cancer and highlight the key outcomes and pitfalls associated with currently used strategies. Finally, we address future directions that could be taken to improve the dendritic cell vaccination outcomes in ovarian cancer.

Abstract

Ovarian cancer (OC) is the deadliest gynecological malignancy in developed countries and is the seventh-highest cause of death in women diagnosed with cancer worldwide. Currently, several therapies are in use against OC, including debulking surgery, chemotherapy, as well as targeted therapies. Even though the current standard-of-care therapies improve survival, a vast majority of OC patients relapse. Additionally, immunotherapies have only resulted in meager patient outcomes, potentially owing to the intricate immunosuppressive nexus within the tumor microenvironment. In this scenario, dendritic cell (DC) vaccination could serve as a potential addition to the therapeutic options available against OC. In this review, we provide an overview of current therapies in OC, focusing on immunotherapies. Next, we highlight the potential of using DC vaccines in OC by underscoring the different DC subsets and their functions in OC. Finally, we provide an overview of the advances and pitfalls of current DC vaccine strategies in OC while providing future perspectives that could improve patient outcomes.

Nanoscale organization of the MHC I peptide-loading complex in human dendritic cells

Dendritic cells (DCs) translate local innate immune responses into long-lasting adaptive immunity by priming antigen-specific T cells. Accordingly, there is an ample interest in exploiting DCs for therapeutic purposes, e.g., in personalized immunotherapies. Despite recent advances in elucidating molecular pathways of antigen processing, in DCs the exact spatial organization of the underlying processes is largely unknown. Here, we unraveled the nanoscale organization of the transporter associated with antigen processing (TAP)-dependent peptide-loading machinery in human monocyte-derived DCs (moDC). We detected an unexpected accumulation of MHC I peptide-loading complexes (PLCs) and TAP-dependent peptide compartmentalization in protrusions of activated DCs. Using single-molecule localization microscopy we revealed that PLCs display homogeneously sized assemblies, independent of the DC activation status or cellular localization. Our data indicate that moDCs show augmentation of subcellular PLC density during DC maturation. We observed a twofold density increase in the cell body, while an even fourfold accumulation was detected in the tips of the protrusions at the mature DC stage in comparison to immature DCs. In these tip regions, PLC assemblies are found along highly compressed tubular ER networks. These findings provide novel insights into nanoscale organization of the antigen presentation machinery, and open new perspectives on the T cell stimulatory capacity of DCs.

Refining the DC-targeting vaccination for preventing emerging infectious diseases

The development of safe, long-term, effective vaccines is still a challenge for many infectious diseases. Thus, the search of new vaccine strategies and production platforms that allow rapidly and effectively responding against emerging or reemerging pathogens has become a priority in the last years. Targeting the antigens directly to dendritic cells (DCs) has emerged as a new approach to enhance the immune response after vaccination. This strategy is based on the fusion of the antigens of choice to monoclonal antibodies directed against specific DC surface receptors such as CD40. Since time is essential, in silico approaches are of high interest to select the most immunogenic and conserved epitopes to improve the T- and B-cells responses. The purpose of this review is to present the advances in DC vaccination, with special focus on DC targeting vaccines and epitope mapping strategies and provide a new framework for improving vaccine responses against infectious diseases.

Vaccine adjuvants to engage the cross-presentation pathway

Adjuvants are indispensable components of vaccines for stimulating optimal immune responses to non-replicating, inactivated and subunit antigens. Eliciting balanced humoral and T cell-mediated immunity is paramount to defend against diseases caused by complex intracellular pathogens, such as tuberculosis, malaria, and AIDS. However, currently used vaccines elicit strong antibody responses, but poorly stimulate CD8 cytotoxic T lymphocyte (CTL) responses. To elicit potent CTL memory, vaccines need to engage the cross-presentation pathway, and this requirement has been a crucial bottleneck in the development of subunit vaccines that engender effective T cell immunity. In this review, we focus on recent insights into DC cross-presentation and the extent to which clinically relevant vaccine adjuvants, such as aluminum-based nanoparticles, water-in oil emulsion (MF59) adjuvants, saponin-based adjuvants, and Toll-like receptor (TLR) ligands modulate DC cross-presentation efficiency. Further, we discuss the feasibility of using carbomer-based adjuvants as next generation of adjuvant platforms to elicit balanced antibody- and T-cell based immunity. Understanding of the molecular mechanism of DC cross-presentation and the mode of action of adjuvants will pave the way for rational design of vaccines for infectious diseases and cancer that require balanced antibody- and T cell-based immunity.

Presence of Dendritic Cell Subsets in Sentinel Nodes of Breast Cancer Patients Is Related to Nodal Burden

BACKGROUND: Sentinel lymph nodes (SLNs) are both the first site where breast cancer (BC) metastases form and where anti-tumoral immunity develops. Despite being the most potent antigen-presenting cells, dendritic cells (DCs) located in a nodal tissue can both promote or suppress immune response against cancer in SLNs. METHODS: In SLNs excisions obtained from 123 invasive BC patients, we performed immunohistochemistry (IHC) for CD1a, CD1c, DC-LAMP, and DC-SIGN to identify different DCs populations. Then we investigated the numbers of DCs subsets in tumor-free, micrometastatic, and macrometastatic SLNs with the use of a light microscope. RESULTS: We observed that CD1c+ and DC-SIGN+ DCs were more numerous in SLNs with a larger tumor size. More abundant intratumoral DC-LAMP+ population was related to a higher number of metastatic lymph nodes. Conversely, more abundant CD1a+ DCs were associated with a decreasing nodal burden in SLNs and a lower number of involved lymph nodes. Moreover, densities of the investigated DC populations differed with respect to tumor grade, HER2 overexpression, hormone receptor status, and histologic type of BC. CONCLUSIONS: According to their subtype, DCs are associated with either lower or higher nodal burden in SLNs from invasive BC patients. These relationships appear to be dependent not only on the maturation state of DCs but also on the histological and biological characteristics of the tumor.

Analysis of Gene Expression and TCR/B Cell Receptor Profiling of Immune Cells in Primary Sjögren's Syndrome by Single-Cell Sequencing

Primary Sjögren's syndrome (pSS) is a chronic autoimmune disease that is estimated to affect 35 million people worldwide and is characterized by lymphocytic infiltration, elevated circulating autoantibodies, and proinflammatory cytokines. The key immune cell subset changes and the TCR/BCR repertoire alterations in pSS patients remain unclear. In this study, we sought to comprehensively characterize the transcriptional changes in PBMCs of pSS patients by single-cell RNA sequencing and single-cell V(D)J sequencing. Naive CD8⁺ T cells and mucosal-associated invariant T cells were markedly decreased but regulatory T cells were increased in pSS patients. There were a large number of differentially expressed genes shared by multiple subpopulations of T cells and B cells. Abnormal signaling pathways, including Ag processing and presentation, the BCR signaling pathway, the TCR signaling pathway, and Epstein-Barr virus infection, were highly enriched in pSS patients. Moreover, there were obvious differences in the CD30, FLT3, IFN-II, IL-1, IL-2, IL-6, IL-10, RESISTIN, TGF-β, TNF, and VEGF signaling networks between pSS patients and healthy controls. Single-cell TCR and BCR repertoire analysis showed that there was a lower diversity of T cells in pSS patients than in healthy controls; however, there was no significant difference in the degree of clonal expansion, CDR3 length distribution, or degree of sequence sharing. Notably, our results further emphasize the functional importance of αβ pairing in determining Ag specificity. In conclusion, our analysis provides a comprehensive single-cell map of gene expression and TCR/BCR profiles in pSS patients for a better understanding of the pathogenesis, diagnosis, and treatment of pSS.

Activation of Cellular Players in Adaptive Immunity via Exogenous Delivery of Tumor Cell Lysates

Tumor cell lysates (TCLs) are a good immunogenic source of tumor-associated antigens. Since whole necrotic TCLs can enhance the maturation and antigen-presenting ability of dendritic cells (DCs), multiple strategies for the exogenous delivery of TCLs have been investigated as novel cancer immunotherapeutic solutions. The TCL-mediated induction of DC maturation and the subsequent immunological response could be improved by utilizing various material-based carriers. Enhanced antitumor immunity and cancer vaccination efficacy could be eventually achieved through the in vivo administration of TCLs. Therefore, (1) important engineering methodologies to prepare antigen-containing TCLs, (2) current therapeutic approaches using TCL-mediated DC activation, and (3) the significant sequential mechanism of DC-based signaling and stimulation in adaptive immunity are summarized in this review. More importantly, the recently reported developments in biomaterial-based exogenous TCL delivery platforms and co-delivery strategies with adjuvants for effective cancer vaccination and antitumor effects are emphasized.

Multiomics reveals persistence of obesity-associated immune cell phenotypes in adipose tissue during weight loss and weight regain in mice

Within adipose tissue (AT), immune cells and parenchymal cells closely interact creating a complex microenvironment. In obesity, immune cell derived inflammation contributes to insulin resistance and glucose intolerance. Diet-induced weight loss improves glucose tolerance; however, weight regain further exacerbates the impairment in glucose homeostasis observed with obesity. To interrogate the immunometabolic adaptations that occur in AT during murine weight loss and weight regain, we utilized cellular indexing of transcriptomes and epitopes by sequencing (CITEseq) in male mice. Obesity-induced imprinting of AT immune cells persisted through weight-loss and progressively worsened with weight regain, ultimately leading to impaired recovery of type 2 regulatory cells, activation of antigen presenting cells, T cell exhaustion, and enhanced lipid handling in macrophages in weight cycled mice. This work provides critical groundwork for understanding the immunological causes of weight cycling-accelerated metabolic disease. For further discovery, we provide an open-access web portal of diet-induced AT immune cell imprinting: https://hastylab.shinyapps.io/MAIseq .

Chromatin accessibility analysis reveals regulatory dynamics and therapeutic relevance of Vogt-Koyanagi-Harada disease

The barrier to curing Vogt-Koyanagi-Harada disease (VKH) is thought to reside in a lack of understanding in the roles and regulations of peripheral inflammatory immune cells. Here we perform a single-cell multi-omic study of 166,149 cells in peripheral blood mononuclear cells from patients with VKH, profile the chromatin accessibility and gene expression in the same blood samples, and uncover prominent cellular heterogeneity. Immune cells in VKH blood are highly activated and pro-inflammatory. Notably, we describe an enrichment of transcription targets for nuclear factor kappa B in conventional dendritic cells (cDCs) that governed inflammation. Integrative analysis of transcriptomic and chromatin maps shows that the RELA in cDCs is related to disease complications and poor prognosis. Ligand-receptor interaction pairs also identify cDC as an important predictor that regulated multiple immune subsets. Our results reveal epigenetic and transcriptional dynamics in auto-inflammation, especially the cDC subtype that might lead to therapeutic strategies in VKH.

Robust temporal map of human in vitro myelopoiesis using single-cell genomics

Myeloid cells are central to homeostasis and immunity. Characterising in vitro myelopoiesis protocols is imperative for their use in research, immunotherapies, and understanding human myelopoiesis. Here, we generate a >470K cells molecular map of human induced pluripotent stem cells (iPSC) differentiation into macrophages. Integration with in vivo single-cell atlases shows in vitro differentiation recapitulates features of yolk sac hematopoiesis, before definitive hematopoietic stem cells (HSC) emerge. The diversity of myeloid cells generated, including mast cells and monocytes, suggests that HSC-independent hematopoiesis can produce multiple myeloid lineages. We uncover poorly described myeloid progenitors and conservation between in vivo and in vitro regulatory programs. Additionally, we develop a protocol to produce iPSC-derived dendritic cells (DC) resembling cDC2. Using CRISPR/Cas9 knock-outs, we validate the effects of key transcription factors in macrophage and DC ontogeny. This roadmap of myeloid differentiation is an important resource for investigating human fetal hematopoiesis and new therapeutic opportunities.

Deciphering Innate Immune Cell-Tumor Microenvironment Crosstalk at a Single-Cell Level

The tumor microenvironment encompasses various innate immune cells which regulate tumor progression. Exploiting innate immune cells is a new frontier of cancer immunotherapy. However, the classical surface markers for cell-type classification cannot always well-conclude the phenotype, which will further hinge our understanding. The innate immune cells include dendritic cells, monocytes/macrophages, natural killer cells, and innate lymphoid cells. They play important roles in tumor growth and survival, in some cases promoting cancer, in other cases negating cancer. The precise characterization of innate immune cells at the single-cell level will boost the potential of cancer immunotherapy. With the development of single-cell RNA sequencing technology, the transcriptome of each cell in the tumor microenvironment can be dissected at a single-cell level, which paves a way for a better understanding of the cell type and its functions. Here, we summarize the subtypes and functions of innate immune cells in the tumor microenvironment based on recent literature on single-cell technology. We provide updates on recent achievements and prospects for how to exploit novel functions of tumor-associated innate immune cells and target them for cancer immunotherapy.

CD206+ tumor-associated macrophages cross-present tumor antigen and drive anti-tumor immunity

In many solid cancers, tumor-associated macrophages (TAM) represent the predominant myeloid cell population. Antigen (Ag) cross-presentation leading to tumor Ag–directed cytotoxic CD8⁺ T cell responses is crucial for antitumor immunity. However, the role of recruited monocyte-derived macrophages, including TAM, as potential cross-presenting cells is not well understood. Here, we show that primary human as well as mouse CD206⁺ macrophages are effective in functional cross-presentation of soluble self-Ag and non–self-Ag, including tumor-associated Ag (TAA), as well as viral Ag. To confirm the presence of cross-presenting TAM in vivo, we performed phenotypic and functional analysis of TAM from B16-F10 and CT26 syngeneic tumor models and have identified CD11b+F4/80hiCD206+ TAM to effectively cross-present TAA. We show that CD11b+CD206+ TAM represent the dominant tumor-infiltrating myeloid cell population, expressing a unique cell surface repertoire, promoting Ag cross-presentation and Ag-specific CD8+ T cell activation comparable with cross-presenting CLEC9A+ DCs (cDC1). The presence of cross-presenting CD206+ TAM is associated with reduced tumor burden in mouse syngeneic tumor models and with improved overall survival in cutaneous melanoma patients. Therefore, the demonstration of effective Ag cross-presentation capabilities of CD206+ TAM, including their clinical relevance, expands our understanding of TAM phenotypic diversity and functional versatility.

Tissue-Resident Immune Cells in Humans

Tissue-resident immune cells span both myeloid and lymphoid cell lineages, have been found in multiple human tissues, and play integral roles at all stages of the immune response, from maintaining homeostasis to responding to infectious challenges to resolution of inflammation to tissue repair. In humans, studying immune cells and responses in tissues is challenging, although recent advances in sampling and high-dimensional profiling have provided new insights into the ontogeny, maintenance, and functional role of tissue-resident immune cells. Each tissue contains a specific complement of resident immune cells. Moreover, resident immune cells for each lineage share core properties, along with tissue-specific adaptations. Here we propose a five-point checklist for defining resident immune cell types in humans and describe the currently known features of resident immune cells, their mechanisms of development, and their putative functional roles within various human organs. We also consider these aspects of resident immune cells in the context of future studies and therapeutics.

Macrophages and Metabolic Reprograming in the Tumor Microenvironment

Due to the emergence of traditional drug resistance in tumor treatment, the anti-cancer therapies are facing multiple challenges. Immunotherapy, as a new and universal treatment, has been gradually concerned. The macrophages, as an important part of the immune system, play an important role in it. Many studies have shown that immune state is essential in cancer progression and prognosis, rebuilding the architecture and functional orientation of the tumor region. Most tumors are complex ecosystems that change temporally and spatially under the pressure of proliferation, apoptosis, and extension of every cell in the microenvironment. Here, we review how macrophages states can be dynamically altered in different metabolic states and we also focus on the formation of immune exhaustion. Finally, we look forward to the explorations of clinical treatment for immune metabolism process.

Nanovaccines with cell-derived components for cancer immunotherapy

Cancer nanovaccines as one of immunotherapeutic approaches are able to attack tumors by stimulating tumor-specific immunological responses. However, there still exist multiple challenges to be tackled for cancer nanovaccines to evoke potent antitumor immunity. Particularly, the administration of exogenous materials may cause the off-target immunotherapy responses. In recent years, biomimetic nanovaccines by using cell lysates, cell-derived nanovesicles, or extracted cell membranes as the functional components have received extensive attention. Such nanovaccines based on cell-derived components would show many unique advantages including inherent biocompatibility and the ability to trigger immune responses against a range of tumor-associated antigens. In this review article, we will introduce the recent research progresses of those cell-derived biomimetic nanovaccines for cancer immunotherapy, and discuss the perspectives and challenges associated with the future clinical translation of these emerging vaccine platforms.

Mutations in the TTN Gene are a Prognostic Factor for Patients with Lung Squamous Cell Carcinomas

Purpose

To analyze the relationship between titin (TTN) mutation gene and tumor mutational burden (TMB) and the with prognosis of lung squamous cell carcinomas (LUSC), and to explore the feasibility of TTN as a potential prognostic marker of for LUSC.

Methods

We analyzed the somatic mutation landscape of LUSC samples using datasets obtained from The Cancer Genome Atlas (TCGA) and International Cancer Genome Consortium (ICGC) databases. Sequence data were divided into wild and mutant groups, and differences in TMB values between the groups compared using a Mann–Whitney U-test. The Kaplan Meier method was used to analyze the correlation between TTN mutation and LUSC prognosis, whereas CIBERSORT algorithm was used to calculate the degree of relative enrichment degree of among tumor-infiltrating lymphocytes in LUSC.

Results

Analysis of both datasets revealed high mutations in the TTN gene, with mutants exhibiting a significantly higher TMB value relative to the wild-type (P < 0.001). Prognosis of the TTN mutant group in LUSC was significantly better than that of wild-type (P = 0.009). Kaplan Meier curves showed that TTN mutation may be an independent prognostic factor in LUSC patients (HR: 0.64, 95% CI 0.48–0.85, P = 0.001), while GSEA analysis revealed that TTN mutation plays a potential role in the development of LUSC. Finally, analysis of LUSC immune microenvironment revealed that TTN mutation was significantly associated with enrichment of macrophages M1 (p < 0.05).

Conclusion

TTN mutation is associated with TMB, and is positively correlated with prognosis of LUSC. Therefore, this mutation may serve as a potential prognostic indicator of LUSC.

Single-cell analysis of human primary prostate cancer reveals the heterogeneity of tumor-associated epithelial cell states

Prostate cancer is the second most common malignancy in men worldwide and consists of a mixture of tumor and non-tumor cell types. To characterize the prostate cancer tumor microenvironment, we perform single-cell RNA-sequencing on prostate biopsies, prostatectomy specimens, and patient-derived organoids from localized prostate cancer patients. We uncover heterogeneous cellular states in prostate epithelial cells marked by high androgen signaling states that are enriched in prostate cancer and identify a population of tumor-associated club cells that may be associated with prostate carcinogenesis. ERG-negative tumor cells, compared to ERG-positive cells, demonstrate shared heterogeneity with surrounding luminal epithelial cells and appear to give rise to common tumor microenvironment responses. Finally, we show that prostate epithelial organoids harbor tumor-associated epithelial cell states and are enriched with distinct cell types and states from their parent tissues. Our results provide diagnostically relevant insights and advance our understanding of the cellular states associated with prostate carcinogenesis.

Myeloid Immune Cells CARrying a New Weapon Against Cancer

Chimeric antigen receptor (CAR) engineering for T cells and natural killer cells (NK) are now under clinical evaluation for the treatment of hematologic cancers. Although encouraging clinical results have been reported for hematologic diseases, pre-clinical studies in solid tumors have failed to prove the same effectiveness. Thus, there is a growing interest of the scientific community to find other immune cell candidate to express CAR for the treatment of solid tumors and other diseases. Mononuclear phagocytes may be the most adapted group of cells with potential to overcome the dense barrier imposed by solid tumors. In addition, intrinsic features of these cells, such as migration, phagocytic capability, release of soluble factors and adaptive immunity activation, could be further explored along with gene therapy approaches. Here, we discuss the elements that constitute the tumor microenvironment, the features and advantages of these cell subtypes and the latest studies using CAR-myeloid immune cells in solid tumor models.

Using RNA-Seq to Investigate Immune-Metabolism Features in Immunocompromised Patients With Sepsis

Objective: Sepsis is life threatening and leads to complex inflammation in patients with immunocompromised conditions, such as cancer, and receiving immunosuppressants for autoimmune diseases and organ transplant recipients. Increasing evidence has shown that RNA-Sequencing (RNA-Seq) can be used to define subendotype in patients with sepsis; therefore, we aim to use RNA-Seq to identify transcriptomic features among immunocompromised patients with sepsis.

Methods: We enrolled patients who were admitted to medical intensive care units (ICUs) for sepsis at a tertiary referral centre in central Taiwan. Whole blood on day-1 and day-8 was obtained for RNA-Seq. We used Gene Set Enrichment Analysis (GSEA) to identify the enriched pathway of day-8/day-1 differentially expressed genes and MiXCR to determine the diversity of T cell repertoire.

Results: A total of 18 immunocompromised subjects with sepsis and 18 sequential organ failure assessment (SOFA) score-matched immunocompetent control subjects were enrolled. The ventilator-day, ICU-stay, and hospital-day were similar between the two groups, whereas the hospital mortality was higher in immunocompromised patients than those in immunocompetent patients (50.0 vs. 5.6%, p < 0.01). We found that the top day-8/day-1 upregulated genes in the immunocompetent group were mainly innate immunity and inflammation relevant genes, namely, PRSS33, HDC, ALOX15, FCER1A, and OLR1, whereas a blunted day-8/day-1 dynamic transcriptome was found among immunocompromised patients with septic. Functional pathway analyses of day-8/day-1 differentially expressed genes identified the upregulated functional biogenesis and T cell-associated pathways in immunocompetent patients recovered from sepsis, whereas merely downregulated metabolism-associated pathways were found in immunocompromised patients with septic. Moreover, we used MiXCR to identify a higher diversity of T cell receptor (TCR) in immunocompetent patients both on day-1 and on day-8 than those in immunocompromised patients.

Conclusions: Using RNA-Seq, we found compromised T cell function, altered metabolic signalling, and decreased T cell diversity among immunocompromised patients with septic, and more mechanistic studies are warranted to elucidate the underlying mechanism.

Neuroinflammation in Amyotrophic Lateral Sclerosis and Frontotemporal Dementia and the Interest of Induced Pluripotent Stem Cells to Study Immune Cells Interactions With Neurons

Inflammation is a shared hallmark between amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). For long, studies were conducted on tissues of post-mortem patients and neuroinflammation was thought to be only bystander result of the disease with the immune system reacting to dying neurons. In the last two decades, thanks to improving technologies, the identification of causal genes and the development of new tools and models, the involvement of inflammation has emerged as a potential driver of the diseases and evolved as a new area of intense research. In this review, we present the current knowledge about neuroinflammation in ALS, ALS-FTD, and FTD patients and animal models and we discuss reasons of failures linked to therapeutic trials with immunomodulator drugs. Then we present the induced pluripotent stem cell (iPSC) technology and its interest as a new tool to have a better immunopathological comprehension of both diseases in a human context. The iPSC technology giving the unique opportunity to study cells across differentiation and maturation times, brings the hope to shed light on the different mechanisms linking neurodegeneration and activation of the immune system. Protocols available to differentiate iPSC into different immune cell types are presented. Finally, we discuss the interest in studying monocultures of iPS-derived immune cells, co-cultures with neurons and 3D cultures with different cell types, as more integrated cellular approaches. The hope is that the future work with human iPS-derived cells helps not only to identify disease-specific defects in the different cell types but also to decipher the synergistic effects between neurons and immune cells. These new cellular tools could help to find new therapeutic approaches for all patients with ALS, ALS-FTD, and FTD.

Significance of CD47 and Its Association With Tumor Immune Microenvironment Heterogeneity in Ovarian Cancer

Background

It was reported that tumor heterogeneity and the surrounding tumor microenvironment (TME) in ovarian cancer affects immunotherapy efficacy and patient outcomes. And the TME of ovarian cancer is intrinsically heterogeneous. CD47 plays vital roles in cell functional behavior and immune homeostasis relating to cancer prognosis. But how it affects TME and its contribution to heterogeneity in ovarian cancer has not been fully illustrated. Therefore, we aimed to identify a prognostic biomarker which may help explain tumor immune microenvironment heterogeneity of ovarian cancer.

Methods

Cancer single-cell state atlas (CancerSEA) was used to evaluate functional role of CD47. Several bioinformatics database including Oncomine, Gene Expression Profiling Interaction Analysis (GEPIA), Tumor Immune Estimation Resource (TIMER), The Human Protein Atlas (HPA), Ualcan and Kaplan-Meier plotter (KM plotter) were applied to illustrate correlation of CD47 with ovarian cancer prognosis and immune infiltration. Tumor Immune Single-cell Hub (TISCH) single cell database was employed to evaluate correlation of CD47 with tumor microenvironment. GeneMANIA was implemented to identify regulation networks of CD47. Differentially expressed genes (DEGs) between CD47 high and low expression groups were analyzed with R package DESeq2. Kyoto encyclopedia of genes and genomes (KEGG) and Gene Set Enrichment Analysis (GSEA) were utilized to explore how CD47 affect the immune related cell signaling pathway.

Results

CD47 expression was upregulated and connected to worse OS and PFS in ovarian cancer. Close relation was found between CD47 expression level and immune infiltration in ovarian cancer, especially with Treg cells, Monocytes, Macrophages and T cell exhaustion (P<0.05). The CD47 expression level was relatively low in plasma cells, dendritic cells and Mono/Macro cells of OV_GSE115007, in myofibroblasts, fibroblasts and endothelial cells of OV_GSE118828, compared to malignant cells of OV_GSE118828 dataset. The cell components and distribution in primary and metastatic ovarian cancer are quite distinct, which may lead to TME heterogeneity of ovarian cancer.

Conclusion

Our results indicated that CD47 is closely correlated to ovarian cancer immune microenvironment and might induce ovarian cancer heterogeneity. Therefore, CD47 may be used as a candidate prognostic biomarker and provide us with new insights into potential immunotherapy in ovarian cancer patients.

Capturing tumour heterogeneity in pre- and post-chemotherapy colorectal cancer ascites-derived cells using single-cell RNA-sequencing

Malignant ascites is an abnormal accumulation of fluid within the peritoneal cavity, caused by metastasis of several types of cancers, including colorectal cancer (CRC). Cancer cells in ascites reflect poor prognosis and serve as a good specimen to study tumour heterogeneity, as they represent a collection of multiple metastatic sites in the peritoneum. In the present study, we have employed single-cell RNA-sequencing (scRNA-seq) to explore and characterise ascites-derived cells from a CRC patient. The samples were prepared using mechanical and enzymatic dissociations, and obtained before and after a chemotherapy treatment. Unbiased clustering of 19,653 cells from four samples reveals 14 subclusters with unique transcriptomic patterns in four major cell types: epithelial cells, myeloid cells, fibroblasts, and lymphocytes. Interestingly, the percentages of cells recovered from different cell types appeared to be influenced by the preparation protocols, with more than 90% reduction in the number of myeloid cells recovered by enzymatic preparation. Analysis of epithelial cell subpopulations unveiled only three out of eleven subpopulations with clear contraction after the treatment, suggesting that the majority of the heterogeneous ascites-derived cells were resistant to the treatment, potentially reflecting the poor treatment outcome observed in the patient. Overall, our study showcases highly heterogeneous cancer subpopulations at single-cell resolution, which respond differently to a particular chemotherapy treatment. All in all, this work highlights the potential benefit of single-cell analyses in planning appropriate treatments and real-time monitoring of therapeutic response in cancer patients through routinely discarded ascites samples.

Engineered CAR-Macrophages as Adoptive Immunotherapies for Solid Tumors

Cellular immunotherapies represent a promising approach for the treatment of cancer. Engineered adoptive cell therapies redirect and augment a leukocyte’s inherent ability to mount an immune response by introducing novel anti-tumor capabilities and targeting moieties. A prominent example of this approach is the use of T cells engineered to express chimeric antigen receptors (CARs), which have demonstrated significant efficacy against some hematologic malignancies. Despite increasingly sophisticated strategies to harness immune cell function, efficacy against solid tumors has remained elusive for adoptive cell therapies. Amongst cell types used in immunotherapies, however, macrophages have recently emerged as prominent candidates for the treatment of solid tumors. In this review, we discuss the use of monocytes and macrophages as adoptive cell therapies. Macrophages are innate immune cells that are intrinsically equipped with broad therapeutic effector functions, including active trafficking to tumor sites, direct tumor phagocytosis, activation of the tumor microenvironment and professional antigen presentation. We focus on engineering strategies for manipulating macrophages, with a specific focus on CAR macrophages (CAR-M). We highlight CAR design for macrophages, the production of CAR-M for adoptive cell transfer, and clinical considerations for their use in treating solid malignancies. We then outline recent progress and results in applying CAR-M as immunotherapies. The recent development of engineered macrophage-based therapies holds promise as a key weapon in the immune cell therapy armamentarium.

Coordinated glucocorticoid receptor and MAFB action induces tolerogenesis and epigenome remodeling in dendritic cells

Glucocorticoids (GCs) exert potent anti-inflammatory effects in immune cells through the glucocorticoid receptor (GR). Dendritic cells (DCs), central actors for coordinating immune responses, acquire tolerogenic properties in response to GCs. Tolerogenic DCs (tolDCs) have emerged as a potential treatment for various inflammatory diseases. To date, the underlying cell type-specific regulatory mechanisms orchestrating GC-mediated acquisition of immunosuppressive properties remain poorly understood. In this study, we investigated the transcriptomic and epigenomic remodeling associated with differentiation to DCs in the presence of GCs. Our analysis demonstrates a major role of MAFB in this process, in synergy with GR. GR and MAFB both interact with methylcytosine dioxygenase TET2 and bind to genomic loci that undergo specific demethylation in tolDCs. We also show that the role of MAFB is more extensive, binding to thousands of genomic loci in tolDCs. Finally, MAFB knockdown erases the tolerogenic properties of tolDCs and reverts the specific DNA demethylation and gene upregulation. The preeminent role of MAFB is also demonstrated in vivo for myeloid cells from synovium in rheumatoid arthritis following GC treatment. Our results imply that, once directly activated by GR, MAFB plays a critical role in orchestrating the epigenomic and transcriptomic remodeling that define the tolerogenic phenotype.

Increased expression of hypoxia-induced factor 1α mRNA and its related genes in myeloid blood cells from critically ill COVID-19 patients

BACKGROUND

COVID-19 counts 46 million people infected and killed more than 1.2 million. Hypoxaemia is one of the main clinical manifestations, especially in severe cases. HIF1α is a master transcription factor involved in the cellular response to oxygen levels. The immunopathogenesis of this severe form of COVID-19 is poorly understood.

METHODS

We performed scRNAseq from leukocytes from five critically ill COVID-19 patients and characterized the expression of hypoxia-inducible factor1α and its transcriptionally regulated genes. Also performed metanalysis from the publicly available RNAseq data from COVID-19 bronchoalveolar cells.

RESULTS

Critically-ill COVID-19 patients show a shift towards an immature myeloid profile in peripheral blood cells, including band neutrophils, immature monocytes, metamyelocytes, monocyte-macrophages, monocytoid precursors, and promyelocytes-myelocytes, together with mature monocytes and segmented neutrophils. May be the result of a physiological response known as emergency myelopoiesis. These cellular subsets and bronchoalveolar cells express HIF1α and their transcriptional targets related to inflammation (CXCL8, CXCR1, CXCR2, and CXCR4); virus sensing, (TLR2 and TLR4); and metabolism (SLC2A3, PFKFB3, PGK1, GAPDH and SOD2).

CONCLUSIONS

The up-regulation and participation of HIF1α in events such as inflammation, immunometabolism, and TLR make it a potential molecular marker for COVID-19 severity and, interestingly, could represent a potential target for molecular therapy. Key messages Critically ill COVID-19 patients show emergency myelopoiesis. HIF1α and its transcriptionally regulated genes are expressed in immature myeloid cells which could serve as molecular targets. HIF1α and its transcriptionally regulated genes is also expressed in lung cells from critically ill COVID-19 patients which may partially explain the hypoxia related events.

Modulation of the immune response by heterogeneous monocytes and dendritic cells in lung cancer

Different subpopulations of monocytes and dendritic cells (DCs) may have a key impact on the modulation of the immune response in malignancy. In this review, we summarize the monocyte and DCs heterogeneity and their function in the context of modulating the immune response in cancer. Subgroups of monocytes may play opposing roles in cancer, depending on the tumour growth and progression as well as the type of cancer. Monocytes can have pro-tumour and anti-tumour functions and can also differentiate into monocyte-derived DCs (moDCs). MoDCs have a similar antigen presentation ability as classical DCs, including cross-priming, a process by which DCs activate CD8 T-cells by cross-presenting exogenous antigens. DCs play a critical role in generating anti-tumour CD8 T-cell immunity. DCs have plastic characteristics and show distinct phenotypes depending on their mature state and depending on the influence of the tumour microenvironment. MoDCs and other DC subsets have been attracting increased interest owing to their possible beneficial effects in cancer immunotherapy. This review also highlights key strategies deploying specific DC subpopulations in combination with other therapies to enhance the anti-tumour response and summarizes the latest ongoing and completed clinical trials using DCs in lung cancer.

Strategy and clinical application of up-regulating cross presentation by DCs in anti-tumor therapy

The cross presentation of exogenous antigen (Ag) by dendritic cells (DCs) facilitates a diversified mode of T-cell activation, orchestrates specific humoral and cellular immunity, and contributes to an efficient anti-tumor immune response. DCs-mediated cross presentation is subject to both intrinsic and extrinsic factors, including the homing and phenotype of DCs, the spatiotemporal trafficking and degradation kinetics of Ag, and multiple microenvironmental clues, with many details largely unexplored. Here, we systemically review the current mechanistic understanding and regulation strategies of cross presentation by heterogeneous DC populations. We also provide insights into the future exploitation of DCs cross presentation for a better clinical efficacy in anti-tumor therapy.

The Therapeutic Potential of Tackling Tumor-Induced Dendritic Cell Dysfunction in Colorectal Cancer

Colorectal cancer (CRC) is the third most diagnosed malignancy and the second leading cause of cancer-related deaths worldwide. Locally advanced and metastatic disease exhibit resistance to therapy and are prone to recurrence. Despite significant advances in standard of care and targeted (immuno)therapies, the treatment effects in metastatic CRC patients have been modest. Untreatable cancer metastasis accounts for poor prognosis and most CRC deaths. The generation of a strong immunosuppressive tumor microenvironment (TME) by CRC constitutes a major hurdle for tumor clearance by the immune system. Dendritic cells (DCs), often impaired in the TME, play a critical role in the initiation and amplification of anti-tumor immune responses. Evidence suggests that tumor-mediated DC dysfunction is decisive for tumor growth and metastasis initiation, as well as for the success of immunotherapies. Unravelling and understanding the complex crosstalk between CRC and DCs holds promise for identifying key mechanisms involved in tumor progression and spread that can be exploited for therapy. The main goal of this review is to provide an overview of the current knowledge on the impact of CRC-driven immunosuppression on DCs phenotype and functionality, and its significance for disease progression, patient prognosis, and treatment response. Moreover, present knowledge gaps will be highlighted as promising opportunities to further understand and therapeutically target DC dysfunction in CRC. Given the complexity and heterogeneity of CRC, future research will benefit from the use of patient-derived material and the development of in vitro organoid-based co-culture systems to model and study DCs within the CRC TME.

Dynamics of TCR repertoire and T cell function in COVID-19 convalescent individuals

SARS-CoV-2 outbreak has been declared by World Health Organization as a worldwide pandemic. However, there are many unknowns about the antigen-specific T-cell-mediated immune responses to SARS-CoV-2 infection. Here, we present both single-cell TCR-seq and RNA-seq to analyze the dynamics of TCR repertoire and immune metabolic functions of blood T cells collected from recently discharged COVID-19 patients. We found that while the diversity of TCR repertoire was increased in discharged patients, it returned to basal level ~1 week after becoming virus-free. The dynamics of T cell repertoire correlated with a profound shift of gene signatures from antiviral response to metabolism adaptation. We also demonstrated that the top expanded T cell clones (~10% of total T cells) display the key anti-viral features in CD8⁺ T cells, confirming a critical role of antigen-specific T cells in fighting against SARS-CoV-2. Our work provides a basis for further analysis of adaptive immunity in COVID-19 patients, and also has implications in developing a T-cell-based vaccine for SARS-CoV-2.

Single-Cell RNA Sequencing Identifies New Inflammation-Promoting Cell Subsets in Asian Patients With Chronic Periodontitis

Periodontitis is a highly prevalent chronic inflammatory disease leading to periodontal tissue breakdown and subsequent tooth loss, in which excessive host immune response accounts for most of the tissue damage and disease progression. Despite of the imperative need to develop host modulation therapy, the inflammatory responses and cell population dynamics which are finely tuned by the pathological microenvironment in periodontitis remained unclear. To investigate the local microenvironment of the inflammatory response in periodontitis, 10 periodontitis patients and 10 healthy volunteers were involved in this study. Single-cell transcriptomic profilings of gingival tissues from two patients and two healthy donors were performed. Histology, immunohistochemistry, and flow cytometry analysis were performed to further validate the identified cell subtypes and their involvement in periodontitis. Based on our single-cell resolution analysis, we identified HLA-DR-expressing endothelial cells and CXCL13⁺ fibroblasts which are highly associated with immune regulation. We also revealed the involvement of the proinflammatory NLRP3⁺ macrophages in periodontitis. We further showed the increased cell-cell communication between macrophage and T/B cells in the inflammatory periodontal tissues. Our data generated an intriguing catalog of cell types and interaction networks in the human gingiva and identified new inflammation-promoting cell subtypes involved in chronic periodontitis, which will be helpful in advancing host modulation therapy.

Regulation of dendritic cell function by Fc-γ-receptors and the neonatal Fc receptor

Dendritic cells (DCs) express receptors to sense pathogens and/or tissue damage and to communicate with other immune cells. Among those receptors, Fc receptors (FcRs) are triggered by the Fc region of antibodies produced during adaptive immunity. In this review, the role of FcγR and neonatal Fc receptor (FcRn) in DC immunity will be discussed. Their expression in DC subsets and impact on antigen uptake and presentation, DC maturation and polarisation of T cell responses will be described. Lastly, we will discuss the importance of FcR-mediated DC function in the context of immunity during viral infection, inflammatory disease, cancer and immunotherapy.

Monocyte-derived APCs are central to the response of PD1 checkpoint blockade and provide a therapeutic target for combination therapy

Background

PD1 immune checkpoint blockade (αPD1 ICB) has shown unparalleled success in treating many types of cancer. However, response to treatment does not always lead to tumor rejection. While αPD1 ICB relies on cytotoxic CD8⁺ T cells, antigen-presenting cells (APCs) at the tumor site are also needed for costimulation of tumor-infiltrating lymphocytes (TILs). It is still unclear how these APCs develop and function before and during αPD1 ICB or how they are associated with tumor rejection.

Methods

Here, we used B16 mouse melanoma and MC38 colorectal carcinoma tumor models, which show differential responses to αPD1 ICB. The immune composition of ICB insensitive B16 and sensitive MC38 were extensively investigated using multi-parameter flow cytometry and unsupervised clustering and trajectory analyses. We additionally analyzed existing single cell RNA sequencing data of the myeloid compartment of patients with melanoma undergoing αPD1 ICB. Lastly, we investigated the effect of CD40 agonistic antibody on the tumor-infiltrating monocyte-derived cells during αPD1 ICB.

Results

We show that monocyte-derived dendritic cells (moDCs) express high levels of costimulatory molecules and are correlated with effector TILs in the tumor microenvironment (TME) after αPD1 ICB only in responding mouse tumor models. Tumor-resident moDCs showed distinct differentiation from monocytes in both mouse and human tumors. We further confirmed significant enrichment of tumor-resident differentiated moDCs in patients with melanoma responding to αPD1 ICB therapy compared with non-responding patients. Moreover, moDCs could be targeted by agonistic anti-CD40 antibody, supporting moDC differentiation, effector T-cell expansion and anti-tumor immunity.

Conclusion

The combined analysis of myeloid and lymphoid populations in the TME during successful and non-successful PD1 ICB led to the discovery of monocyte-to-DC differentiation linked to expanding T-cell populations. This differentiation was found in patients during ICB, which was significantly higher during successful ICB. The finding of tumor-infiltrating monocytes and differentiating moDCs as druggable target for rational combination therapy opens new avenues of anti-tumor therapy design.

Phagocytic function of tumor-associated macrophages as a key determinant of tumor progression control: a review

Tumor-associated macrophage (TAM) phagocytic activity is emerging as a new mechanism to harness for cancer treatment. Currently, many approaches are investigated at the preclinical level and some modalities have now reached clinical trials, including the targeting of the phagocytosis inhibitor CD47. The rationale for increasing TAM phagocytic activity is to improve innate anticancer immunity, and to promote T-cell mediated adaptive immune responses. In this context, a clear understanding of the impact of TAM phagocytosis on both innate and adaptive immunity is critical. Indeed, uncertainties persist regarding the capacity of TAM to present tumor antigens to CD8 T cells by cross-presentation. This process is critical for an optimal cytotoxic T-cell immune response and can be mediated by dendritic cells but also potentially by macrophages. In addition, the engulfment of cancer cells affects TAM functionality, as apoptotic cell uptake (a process termed efferocytosis) promotes macrophage anti-inflammatory functions. Because of the abundance of TAM in most solid tumors and the common use of apoptosis inducers such as radiotherapy to treat patients with cancer, efferocytosis potentially affects the overall immune balance within the tumor microenvironment (TME). In this review, we will discuss how cancer cell phagocytosis by TAM impacts antitumor immunity. First, we will focus on the potential of the phagocytic activity of TAM per se to control tumor progression. Second, we will examine the potential of TAM to act as antigen presenting cells for tumor specific CD8 T cells, considering the different characteristics of this process in the tumor tissue and at the molecular level. Finally, we will see how phagocytosis and efferocytosis affect TAM functionality and how these mechanisms impact on antitumor immunity. A better understanding of these aspects will enable us to better predict and interpret the consequences of cancer therapies on the immune status of the TME. Future cancer treatment regimens can thereby be designed to not only impact directly on cancer cells, but also to favorably modulate TAM phagocytic activity to benefit from the potential of this central immune player to achieve more potent therapeutic efficacy.

May the Force Be with You (Or Not): The Immune System under Microgravity

All terrestrial organisms have evolved and adapted to thrive under Earth's gravitational force. Due to the increase of crewed space flights in recent years, it is vital to understand how the lack of gravitational forces affects organisms. It is known that astronauts who have been exposed to microgravity suffer from an array of pathological conditions including an impaired immune system, which is one of the most negatively affected by microgravity. However, at the cellular level a gap in knowledge exists, limiting our ability to understand immune impairment in space. This review highlights the most significant work done over the past 10 years detailing the effects of microgravity on cellular aspects of the immune system.

CD169 Defines Activated CD14+ Monocytes With Enhanced CD8+ T Cell Activation Capacity

Monocytes are antigen-presenting cells (APCs) that play diverse roles in promoting or regulating inflammatory responses, but their role in T cell stimulation is not well defined. In inflammatory conditions, monocytes frequently show increased expression of CD169/Siglec-1, a type-I interferon (IFN-I)-regulated protein. However, little is known about the phenotype and function of these CD169⁺ monocytes. Here, we have investigated the phenotype of human CD169⁺ monocytes in different diseases, their capacity to activate CD8⁺ T cells, and the potential for a targeted-vaccination approach. Using spectral flow cytometry, we detected CD169 expression by CD14⁺ CD16^- classical and CD14⁺ CD16⁺ intermediate monocytes and unbiased analysis showed that they were distinct from dendritic cells, including the recently described CD14-expressing DC3. CD169⁺ monocytes expressed higher levels of co-stimulatory and HLA molecules, suggesting an increased activation state. IFNα treatment highly upregulated CD169 expression on CD14⁺ monocytes and boosted their capacity to cross-present antigen to CD8⁺ T cells. Furthermore, we observed CD169⁺ monocytes in virally-infected patients, including in the blood and bronchoalveolar lavage fluid of COVID-19 patients, as well as in the blood of patients with different types of cancers. Finally, we evaluated two CD169-targeting nanovaccine platforms, antibody-based and liposome-based, and we showed that CD169⁺ monocytes efficiently presented tumor-associated peptides gp100 and WT1 to antigen-specific CD8⁺ T cells. In conclusion, our data indicate that CD169⁺ monocytes are activated monocytes with enhanced CD8⁺ T cell stimulatory capacity and that they emerge as an interesting target in nanovaccine strategies, because of their presence in health and different diseases.

Mimicking Pathogens to Augment the Potency of Liposomal Cancer Vaccines

Liposomes have emerged as interesting vehicles in cancer vaccination strategies as their composition enables the inclusion of both hydrophilic and hydrophobic antigens and adjuvants. In addition, liposomes can be decorated with targeting moieties to further resemble pathogenic particles that allow for better engagement with the immune system. However, so far liposomal cancer vaccines have not yet reached their full potential in the clinic. In this review, we summarize recent preclinical studies on liposomal cancer vaccines. We describe the basic ingredients for liposomal cancer vaccines, tumor antigens, and adjuvants, and how their combined inclusion together with targeting moieties potentially derived from pathogens can enhance vaccine immunogenicity. We discuss newly identified antigen-presenting cells in humans and mice that pose as promising targets for cancer vaccines. The lessons learned from these preclinical studies can be applied to enhance the efficacy of liposomal cancer vaccination in the clinic.

The Crosstalk Between Dendritic Cells, Cytokine-Induced Killer Cells And Cancer Cells From The Perspective Of Combination Therapy

Dendritic cells (DCs) are considered the most potent professional antigen-presenting cells (APCs) that elicit adaptive antitumour immunity. DCs integrate multiple environmental signals by efficiently processing tumour-associated antigens (TAAs) and migrating to draining lymph nodes (dLNs), where they present foreign antigens to T cells for priming. DCs thus serve as a major link between innate and adaptive immunity. Although DCs (mostly monocyte-derived DCs [mo-DCs]) have already been used in cancer therapies, such approaches have shown limited efficacy. Mo-DCs have the unique ability to present antigens to T cells in peripheral tissues. CD3+CD56+ cytokine-induced killer (CIK) cells are characterized by both MHC-restricted and MHC-unrestricted antitumour cytotoxicity against a broad range of cancer cells. This review presents an overview of the mechanisms by which mo-DCs and CIK cells’ interact with each other and with tumours. The maturation of DCs was identified as a crucial step in the development of effective DC-based vaccines against cancer. A further improved adoptive immunotherapy strategy involves a combination of mature mo-DCs and CIK cells. Combination therapy presents many opportunities for cancer treatment, as reported by a number of clinical trials. However, there is a lack of fundamental studies on the interaction of in vitro-generated mo-DCs with CIK cells. We discuss several methods of boosting DC-based vaccines and review the current knowledge of contact-dependent and cytokine-induced interactions of mo-DCs with CIK cells. We highlight that the combination of mo-DCs with CIK cells activates MHC-restricted and MHC-unrestricted immune responses.

Profiling of T Cell Repertoire in SARS-CoV-2-Infected COVID-19 Patients Between Mild Disease and Pneumonia

The coronavirus disease 2019 (COVID-19) pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has become a public health emergency. The most common symptoms of COVID-19 are fever, cough, and fatigue. While most patients with COVID-19 present with mild illness, some patients develop pneumonia, an important risk factor for mortality, at early stage of viral infection, putting these patients at increased risk of death. So far, little has been known about differences in the T cell repertoires between COVID-19 patients with and without pneumonia during SARS-CoV-2 infection. Herein, we aimed to investigate T cell receptor (TCR) repertoire profiles and patient-specific SARS-CoV-2-associated TCR clusters between COVID-19 patients with mild disease (no sign of pneumonia) and pneumonia. The TCR sequencing was conducted to characterize the peripheral TCR repertoire profile and diversity. The TCR clustering and CDR3 annotation were exploited to further discover groups of patient-specific TCR clonotypes with potential SARS-CoV-2 antigen specificities. Our study indicated a slight decrease in the TCR repertoire diversity and a skewed CDR3 length usage in patients with pneumonia compared to those with mild disease. The SARS-CoV-2-associated TCR clusters enriched in patients with mild disease exhibited significantly higher TCR generation probabilities and most of which were highly shared among patients, compared with those from pneumonia patients. Importantly, using similarity network-based clustering followed by the sequence conservation analysis, we found different patterns of CDR3 sequence motifs between mild disease- and pneumonia-specific SARS-CoV-2-associated public TCR clusters. Our results showed that characteristics of overall TCR repertoire and SARS-CoV-2-associated TCR clusters/clonotypes were divergent between COVID-19 patients with mild disease and patients with pneumonia. These findings provide important insights into the correlation between the TCR repertoire and disease severity in COVID-19 patients.

Single-cell Transcriptomics Uncover a Novel Role of Myeloid Cells and T-lymphocytes in the Fibrotic Microenvironment in Peyronie's Disease

BACKGROUND

Peyronie's disease (PD) is an acquired fibrotic disease affecting the penile tunica albuginea that can lead to curvature and deformities, shortening, and erectile dysfunction. Although immunological mechanisms have been suggested for the pathophysiology of PD, these have not been investigated using single-cell transcriptomics.

OBJECTIVE

To investigate the immunological signature of plaques from PD patients using immunohistochemistry (IHC) and single-cell RNA sequencing (scRNA-Seq).

DESIGN, SETTING, AND PARTICIPANTS

Tunica albuginea biopsy was performed in patients undergoing penile surgery for either PD (n = 12) or plication or penile cancer (control, n = 6). The inclusion criteria for PD patients were stable chronic disease (≥12 mo in duration) and no previous penile surgery or intralesional injection therapy.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

IHC was performed on surgical samples from ten patients with PD and five control subjects. An additional two PD and one control sample were used for scRNA-Seq (droplet-based; 10X Genomics). Cell clusters were visualised using heatmaps and t-distributed stochastic neighbour embedding plots (BioTuring v2.7.5).

RESULTS AND LIMITATIONS

IHC revealed the presence of myeloid dendritic cells (DCs; CD68⁺, TLR4⁺, CD206⁺), cytotoxic T lymphocytes (CTLs; CD3⁺, CD8⁺), and B lymphocytes (CD20⁺) in PD plaques, which were absent in controls. scRNA-Seq yielded results for 3312 PD and 5658 control cells. Cell clusters contained fibroblasts (COL1A2⁺), myofibroblasts (COL1A2⁺, ACTA2⁺), smooth muscle cells (ACTA2⁺, DES⁺), endothelial cells (VWF⁺), myeloid cells (CD14⁺), T lymphocytes (CD3D⁺), and neutrophils (ALPL⁺). Myeloid cell subclustering showed infiltration of monocyte-derived cells; control tissue contained classical DCs and resident macrophages. Lymphocyte subclustering revealed mucosal-associated invariant T (MAIT) cells and CTLs in PD. Differential gene expression suggests an increase in inflammatory and immune responses in chronic PD. The study is limited by the small scRNA-seq sample size (n = 3) for IHC, mitigated by a larger cohort of historic paraffin-embedded samples (n = 15), which showed largely parallel findings. Owing to tissue stiffness and extracellular matrix adhesion, our single-cell yield was lower for PD than for the control sample.

CONCLUSIONS

Our data suggest that even in the chronic PD stage (painless and stable curvature) there is a sustained inflammatory reaction. While vascularisation and collagen production are elevated, the inflammation is driven by specialised monocyte-derived CTL and MAIT cells. These findings could uncover new avenues for medical treatment of PD.

PATIENT SUMMARY

We looked at the role of the immune system in patients suffering from Peyronie's disease, a condition causing shortening and curvature of the penis. We found that even in a stable, chronic stage of the disease, there is activation of the immune system. Our results suggest that there is potential for novel treatments for this condition.

Palmitoylated antigens for the induction of anti-tumor CD8+ T cells and enhanced tumor recognition

Induction of tumor-specific cytotoxic CD8⁺ T cells (CTLs) via immunization relies on the presentation of tumor-associated peptides in major histocompatibility complex (MHC) class I molecules by dendritic cells (DCs). To achieve presentation of exogenous peptides into MHC class I, cytosolic processing and cross-presentation are required. Vaccination strategies aiming to induce tumor-specific CD8⁺ T cells via this exogenous route therefore pose a challenge. In this study, we describe improved CD8⁺ T cell induction and in vivo tumor suppression of mono-palmitic acid-modified (C16:0) antigenic peptides, which can be attributed to their unique processing route, efficient receptor-independent integration within lipid bilayers, and continuous intracellular accumulation and presentation through MHC class I. We propose that this membrane-integrating feature of palmitoylated peptides can be exploited as a tool for quick and efficient antigen enrichment and MHC class I loading. Importantly, both DCs and non-professional antigen-presenting cells (APCs), similar to tumor cells, facilitate anti-tumor immunity by efficient CTL priming via DCs and effective recognition of tumors through enhanced presentation of antigens.

Human anogenital monocyte-derived dendritic cells and langerin+cDC2 are major HIV target cells

Tissue mononuclear phagocytes (MNP) are specialised in pathogen detection and antigen presentation. As such they deliver HIV to its primary target cells; CD4 T cells. Most MNP HIV transmission studies have focused on epithelial MNPs. However, as mucosal trauma and inflammation are now known to be strongly associated with HIV transmission, here we examine the role of sub-epithelial MNPs which are present in a diverse array of subsets. We show that HIV can penetrate the epithelial surface to interact with sub-epithelial resident MNPs in anogenital explants and define the full array of subsets that are present in the human anogenital and colorectal tissues that HIV may encounter during sexual transmission. In doing so we identify two subsets that preferentially take up HIV, become infected and transmit the virus to CD4 T cells; CD14⁺CD1c⁺ monocyte-derived dendritic cells and langerin-expressing conventional dendritic cells 2 (cDC2).

The Tumour Vasculature as a Target to Modulate Leucocyte Trafficking

Simple Summary

Tumour blood vessels, characterised by abnormal morphology and function, create an immunosuppressive tumour microenvironment via restricting the appropriate leucocyte subsets trafficking. Strategies to trigger phenotypic alteration in tumour vascular system to resemble normal vascular system, named vascular normalisation, promote effective trafficking of leucocytes into tumours through enhancing the interactions between leucocytes and endothelial cells. This review specifically demonstrates how targeting tumour blood vessels modulates the critical steps of leucocyte trafficking. Furthermore, selective regulation of leucocyte subsets trafficking in tumours can be achieved by vasculature-targeting strategies, contributing to improved immunotherapy and thereby delayed tumour progression.

Abstract

The effectiveness of immunotherapy against solid tumours is dependent on the appropriate leucocyte subsets trafficking and accumulating in the tumour microenvironment (TME) with recruitment occurring at the endothelium. Such recruitment involves interactions between the leucocytes and the endothelial cells (ECs) of the vessel and occurs through a series of steps including leucocyte capture, their rolling, adhesion, and intraluminal crawling, and finally leucocyte transendothelial migration across the endothelium. The tumour vasculature can curb the trafficking of leucocytes through influencing each step of the leucocyte recruitment process, ultimately producing an immunoresistant microenvironment. Modulation of the tumour vasculature by strategies such as vascular normalisation have proven to be efficient in facilitating leucocyte trafficking into tumours and enhancing immunotherapy. In this review, we discuss the underlying mechanisms of abnormal tumour vasculature and its impact on leucocyte trafficking, and potential strategies for overcoming the tumour vascular abnormalities to boost immunotherapy via increasing leucocyte recruitment.

A Shift Towards an Immature Myeloid Profile in Peripheral Blood of Critically Ill COVID-19 Patients

BACKGROUND

SARS-CoV-2, the etiological agent causing COVID-19, has infected more than 27 million people with over 894000 deaths worldwide since its emergence in December 2019. Factors for severe diseases, such as diabetes, hypertension, and obesity have been identified however, the precise pathogenesis is poorly understood. To understand its pathophysiology and to develop effective therapeutic strategies, it is essential to define the prevailing immune cellular subsets.

METHODS

We performed whole circulating immune cells scRNAseq from five critically ill COVID-19 patients, trajectory and gene ontology analysis.

RESULTS

Immature myeloid populations, such as promyelocytes-myelocytes, metamyelocytes, band neutrophils, monocytoid precursors, and activated monocytes predominated. The trajectory with pseudotime analysis supported the finding of immature cell states. While the gene ontology showed myeloid cell activation in immune response, DNA and RNA processing, defense response to the virus, and response to type 1 interferon. Lymphoid lineage was scarce. Expression of genes such as C/EBPβ, IRF1and FOSL2 potentially suggests the induction of trained immunity.

CONCLUSIONS

Our results uncover transcriptomic profiles related to immature myeloid lineages and suggest the potential induction of trained immunity.