Immune regulation by CD8+ Treg cells: novel possibilities for anticancer immunotherapy

The Mutational and Microenvironmental Landscape of Cutaneous Squamous Cell Carcinoma: A Review

Cutaneous squamous cell carcinoma (cSCC) manifests through the complex interactions of UV-induced DNA damage, genetic mutations, and alterations in the tumor microenvironment. A high mutational burden is present in cSCC, as well as both cSCC precursors and normal skin, making driver genes difficult to differentiate. Despite this, several key driver genes have been identified, including TP53, the NOTCH family, CDKN2A, PIK3CA, and EGFR. In addition to mutations, the tumor microenvironment and the manipulation and evasion of the immune system play a critical role in cSCC progression. Novel therapeutic approaches, such as immunotherapy and EGFR inhibitors, have been used to target these dysregulations, and have shown promise in treating advanced cSCC cases, emphasizing the need for targeted interventions considering both genetic and microenvironmental factors for improved patient outcomes.

Roles of exosomes in immunotherapy for solid cancers

Although immunotherapy has made breakthrough progress, its efficacy in solid tumours remains unsatisfactory. Exosomes are the main type of extracellular vesicles that can deliver various intracellular molecules to adjacent or distant cells and organs, mediating various biological functions. Studies have found that exosomes can both activate the immune system and inhibit the immune system. The antigen and major histocompatibility complex (MHC) carried in exosomes make it possible to develop them as anticancer vaccines. Exosomes derived from blood, urine, saliva and cerebrospinal fluid can be used as ideal biomarkers in cancer diagnosis and prognosis. In recent years, exosome-based therapy has made great progress in the fields of drug transportation and immunotherapy. Here, we review the composition and sources of exosomes in the solid cancer immune microenvironment and further elaborate on the potential mechanisms and pathways by which exosomes influence immunotherapy for solid cancers. Moreover, we summarize the potential clinical application prospects of engineered exosomes and exosome vaccines in immunotherapy for solid cancers. Eventually, these findings may open up avenues for determining the potential of exosomes for diagnosis, treatment, and prognosis in solid cancer immunotherapy.

The future of cancer immunotherapy: DNA vaccines leading the way

Immuno-oncology has revolutionized cancer treatment and has opened up new opportunities for developing vaccination methods. DNA-based cancer vaccines have emerged as a promising approach to activating the bodily immune system against cancer. Plasmid DNA immunizations have shown a favorable safety profile and there occurs induction of generalized as well as tailored immune responses in preclinical and early-phase clinical experiments. However, these vaccines have notable limitations in immunogenicity and heterogeneity and these require refinements. DNA vaccine technology has been focusing on improving vaccine efficacy and delivery, with parallel developments in nanoparticle-based delivery systems and gene-editing technologies such as CRISPR/Cas9. This approach has showcased great promise in enhancing and tailoring the immune response to vaccination. Strategies to enhance the efficacy of DNA vaccines include the selection of appropriate antigens, optimizing insertion in a plasmid, and studying combinations of vaccines with conventional strategies and targeted therapies. Combination therapies have attenuated immunosuppressive activities in the tumor microenvironment and enhanced the capability of immune cells. This review provides an overview of the current framework of DNA vaccines in oncology and focuses on novel strategies, including established combination therapies and those still under development.The challenges that oncologists, scientists, and researchers need to overcome to establish DNA vaccines as an avant-garde approach to defeating cancer, are also emphasized. The clinical implications of the immunotherapeutic approaches and the need for predictive biomarkers have also been reviewed upon. We have also tried to extend the role of Neutrophil extracellular traps (NETs) to the DNA vaccines. The clinical implications of the immunotherapeutic approaches have also been reviewed upon. Ultimately, refining and optimizing DNA vaccines will enable harnessing the immune system's natural ability to recognize and eliminate cancer cells, leading the world towards a revolution in cancer cure.

Circulating CD4+ Treg, CD8+ Treg, and CD3+ γδ T Cell Subpopulations in Ovarian Cancer

Background and Objectives: Regulatory T cells (Tregs) are usually enriched in ovarian cancer (OC), and their immunosuppressive function plays a key role in tumorigenesis and progression. We mainly explored the phenotypical characterization of Treg-related markers on αβ and γδ T cell subsets in patients with OC. Materials and Methods: Thirty-six untreated patients with OC at the Women's Hospital of Nanjing Medical University from September 2019 to August 2021 were enrolled. Phenotypical characterization of Tregs-related markers were detected by flow cytometry (FCM). Enzyme-linked immunosorbent assay was used to detect the levels of carbohydrate antigen (CA125) and transforming growth factor β (TGF-β). The level of human epididymis protein 4 (HE4) was detected by electrochemiluminescence immunoassay. Results: Circulating CD4⁺ Tregs, CD8⁺ Tregs, and CD3⁺γδ T cell subpopulations from OC patients have elevated Foxp3, CD25, CD122, Vδ1, and reduced CD28 expression compared to benign ovarian tumor (BOT) patients and healthy controls (HC). The upregulation of Foxp3 and Vδ1 and the downregulation of CD28 were highly specific for maintaining the immunosuppression function of CD4⁺ Tregs, CD3⁺γδ T cells, and CD8⁺ Tregs in OC patients. These Treg subpopulations were able to discriminate OC from BOT and HC. The levels of CA125, HE4, and TGF-β were increased in OC patients. A significant positive correlation between Treg subpopulations and CA125, HE4, and TGF-β was revealed. Conclusions: Proportions of CD4⁺ Tregs, CD8+ Tregs, and CD3⁺γδ T cell subsets were significantly increased in OC patients and were positively correlated with FIGO stage/metastasis status, CA125, HE4, and TGF-β. These indicators have the potential to be used as immunosurveillance biomarkers for OC.

Understanding the squamous cell carcinoma immune microenvironment

Primary cutaneous squamous cell carcinoma (cSCC) is the second most common human cancer with a rising incidence of about 1.8 million in the United States annually. Primary cSCC is usually curable by surgery; however, in some cases, cSCC eventuates in nodal metastasis and death from disease specific death. cSCC results in up to 15,000 deaths each year in the United States. Until recently, non-surgical options for treatment of locally advanced or metastatic cSCC were largely ineffective. With the advent of checkpoint inhibitor immunotherapy, including cemiplimab and pembrolizumab, response rates climbed to 50%, representing a vast improvement over chemotherapeutic agents used previously. Herein, we discuss the phenotype and function of SCC associated Langerhans cells, dendritic cells, macrophages, myeloid derived suppressor cells and T cells as well as SCC-associated lymphatics and blood vessels. Possible role(s) of SCC-associated cytokines in progression and invasion are reviewed. We also discuss the SCC immune microenvironment in the context of currently available and pipeline therapeutics.

Recent highlights in the immunomodulatory aspects of Treg cell-derived extracellular vesicles: special emphasis on autoimmune diseases and transplantation

In order to maintain immunological tolerance to self and non-self antigens, one’s T regulatory (Treg) cells play a critical role in the regulation of detrimental inflammation. Treg cells inhibit the immune system in a variety of ways, some of which are contact-dependent and the others are soluble factors. Extracellular vesicles (EVs) are mainly secretory membrane structures that play a pivotal role in intercellular communication in both the local and systemic environments, enabling the transport of proteins, lipids, and nucleic acids between immune and non-immune cells. A number of studies have shown that Treg-derived EVs are specially formulated intercellular exchanging devices capable of regulating immunological responses by producing a cell-free tolerogenic milieu. Some of the processes suggested include miRNA-induced gene shutdown and upmodulation, surface protein activity, and enzyme transfer. Instead of being influenced by external circumstances like Tregs, exosomes’ cohesive structure allows them to transmit their charge intact across the blood–brain barrier and deliver it to the target cell with particular receptors. These properties have resulted in the use of Treg-derived EVs' immunomodulatory effects moving beyond laboratory research and into preclinical applications in animal models of a variety of inflammatory, autoimmune, and transplant rejection disorders. However, insufficient evidence has been produced to permit enrollment in human clinical studies. As such, we begin our research by introducing the most potent immunosuppressive elements discovered in Treg-derived EVs elucidating likely mechanisms of action in inhibiting immunological responses. Following that, we address recent research on the potential of suppressive EVs to regulate autoimmune inflammatory responses and improve tissue transplant survival.

Metabolic reprogramming of the tumor immune microenvironment in ovarian cancer: A novel orientation for immunotherapy

Ovarian cancer is the most lethal gynecologic tumor, with the highest mortality rate. Numerous studies have been conducted on the treatment of ovarian cancer in the hopes of improving therapeutic outcomes. Immune cells have been revealed to play a dual function in the development of ovarian cancer, acting as both tumor promoters and tumor suppressors. Increasingly, the tumor immune microenvironment (TIME) has been proposed and confirmed to play a unique role in tumor development and treatment by altering immunosuppressive and cytotoxic responses in the vicinity of tumor cells through metabolic reprogramming. Furthermore, studies of immunometabolism have provided new insights into the understanding of the TIME. Targeting or activating metabolic processes of the TIME has the potential to be an antitumor therapy modality. In this review, we summarize the composition of the TIME of ovarian cancer and its metabolic reprogramming, its relationship with drug resistance in ovarian cancer, and recent research advances in immunotherapy.

Nanomedicine Strategies for Heating "Cold" Ovarian Cancer (OC): Next Evolution in Immunotherapy of OC

Immunotherapy has revolutionized cancer treatment, dramatically improving survival rates of melanoma and lung cancer patients. Nevertheless, immunotherapy is almost ineffective against ovarian cancer (OC) due to its cold tumor immune microenvironment (TIM). Many traditional medications aimed at remodeling TIM are often associated with severe systemic toxicity, require frequent dosing, and show only modest clinical efficacy. In recent years, emerging nanomedicines have demonstrated extraordinary immunotherapeutic effects for OC by reversing the TIM because the physical and biochemical features of nanomedicines can all be harnessed to obtain optimal and expected tissue distribution and cellular uptake. However, nanomedicines are far from being widely explored in the field of OC immunotherapy due to the lack of appreciation for the professional barriers of nanomedicine and pathology, limiting the horizons of biomedical researchers and materials scientists. Herein, a typical cold tumor-OC is adopted as a paradigm to introduce the classification of TIM, the TIM characteristics of OC, and the advantages of nanomedicines for immunotherapy. Subsequently, current nanomedicines are comprehensively summarized through five general strategies to substantially enhance the efficacy of immunotherapy by heating the cold OC. Finally, the challenges and perspectives of this expanding field for improved development of clinical applications are also discussed.

FoxP3+ CD8 T-cells in acute HIV infection and following early antiretroviral therapy initiation

Objectives

Besides CD4 regulatory T-cells (Tregs), immunosuppressor FoxP3+ CD8 T-cells are emerging as an important subset of Tregs, which contribute to immune dysfunction and disease progression in HIV infection. However, FoxP3+ CD8 T-cell dynamics in acute HIV infection and following early antiretroviral therapy (ART) initiation remain understudied.

Methods

Subsets of FoxP3+ CD8 T-cells were characterized both prospectively and cross-sectionally in PBMCs from untreated acute (n=26) and chronic (n=10) HIV-infected individuals, early ART-treated in acute infection (n=10, median of ART initiation: 5.5 months post-infection), ART-treated in chronic infection (n=10), elite controllers (n=18), and HIV-uninfected controls (n=21).

Results

Acute and chronic infection were associated with increased total, effector memory, and terminally differentiated FoxP3+ CD8 T-cells, while early ART normalized only the frequencies of total FoxP3+ CD8 T-cells. We observed an increase in FoxP3+ CD8 T-cell immune activation (HLADR+/CD38+), senescence (CD57+/CD28-), and PD-1 expression during acute and chronic infection, which were not normalized by early ART. FoxP3+ CD8 T-cells in untreated participants expressed higher levels of immunosuppressive LAP(TGF-β1) and CD39 than uninfected controls, whereas early ART did not affect their expression. The expression of gut-homing markers CCR9 and Integrin-β7 by total FoxP3+ CD8 T-cells and CD39+ and LAP(TGF-β1)+ FoxP3+ CD8 T-cells increased in untreated individuals and remained higher than in uninfected controls despite early ART. Elite controllers share most of the FoxP3+ CD8 T-cell characteristics in uninfected individuals.

Conclusions

Although early ART normalized total FoxP3+ CD8 T-cells frequencies, it did not affect the persistent elevation of the gut-homing potential of CD39+ and LAP(TGF-β1)+ FoxP3+ CD8 T-cell, which may contribute to immune dysfunction.

Plasmacytoid Dendritic Cells, a Novel Target in Myeloid Neoplasms

Plasmacytoid dendritic cells (pDC) are the main type I interferon producing cells in humans and are able to modulate innate and adaptive immune responses. Tumor infiltration by plasmacytoid dendritic cells is already well described and is associated with poor outcomes in cancers due to the tolerogenic activity of pDC. In hematological diseases, Blastic Plasmacytoid Dendritic Cells Neoplasm (BPDCN), aggressive leukemia derived from pDCs, is well described, but little is known about tumor infiltration by mature pDC described in Myeloid Neoplasms (MN). Recently, mature pDC proliferation (MPDCP) has been described as a differential diagnosis of BPDCN associated with acute myeloid leukemia (pDC-AML), myelodysplastic syndrome (pDC-MDS) and chronic myelomonocytic leukemia (pDC-CMML). Tumor cells are myeloid blasts and/or mature myeloid cells from related myeloid disorders and pDC derived from a clonal proliferation. The poor prognosis associated with MPDCP requires a better understanding of pDC biology, MN oncogenesis and immune response. This review provides a comprehensive overview about the biological aspects of pDCs, the description of pDC proliferation in MN, and an insight into putative therapies in pDC-AML regarding personalized medicine.

Circulating and Tumor-Infiltrating Immune Checkpoint-Expressing CD8+ Treg/T Cell Subsets and Their Associations with Disease-Free Survival in Colorectal Cancer Patients

Simple Summary

Colorectal cancer is one of the leading causes of global cancer-related mortality. Tumor-infiltrating effector immune cells play critical roles in tumor control, and their activity can dictate disease outcomes. In this study, we provide evidence of the associations between different CD8⁺ T cell subpopulations with disease-free survival (DFS) in CRC patients. We report associations between higher levels of certain circulating and tumor-infiltrating CD8⁺ T cell subsets and improved clinical outcomes in CRC patients.

Abstract

T cells in the tumor microenvironment (TME) have diverse roles in anti-tumor immunity, including orchestration of immune responses and anti-tumor cytotoxic attack. However, different T cell subsets may have opposing roles in tumor progression, especially in inflammation-related cancers such as colorectal cancer (CRC). In this study, we phenotypically characterized CD3⁺CD4^- (CD8⁺) T cells in colorectal tumor tissues (TT), normal colon tissues (NT) and in circulation of CRC patients. We investigated the expression levels of key immune checkpoints (ICs) and Treg-related markers in CD8⁺ T cells. Importantly, we investigated associations between different tumor-infiltrating CD8⁺ T cell subpopulations and disease-free survival (DFS) in CRC patients. We found that FoxP3 expression and ICs including PD-1, CTLA-4, TIM-3, and LAG-3 were significantly increased in tumor-infiltrating CD8⁺ T cells compared with NT and peripheral blood. In the TME, we found that TIM-3 expression was significantly increased in patients with early stages and absent lymphovascular invasion (LVI) compared to patients with advanced stages and LVI. Importantly, we report that high levels of certain circulating CD8⁺ T cell subsets (TIM-3-expressing, FoxP3⁻Helios⁻TIM-3⁺ and FoxP3⁻Helios⁺TIM-3⁺ cells) in CRC patients were associated with better DFS. Moreover, in the TME, we report that elevated levels of CD25⁺ and TIM-3⁺ T cells, and FoxP3⁺Helios⁻TIM-3⁺ Tregs were associated with better DFS.

Leukemia derived dendritic cell (DCleu) mediated immune response goes along with reduced (leukemia-specific) regulatory T-cells

The blastmodulatory Kit-M, composed of granulocyte-macrophage colony-stimulating-factor (GM-CSF) and Prostaglandin E1 (PGE₁), is known to convert myeloid leukaemic blasts (from AML patients) into leukaemia derived dendritic cells (DC_leu), which activate immunoreactive cells to gain antileukemic/leukaemia-specific activity. In this study we had a special focus on the influence of Kit-M treated, DC/DCleu containing patients'whole blood (WB, n = 16) on the provision of immunosuppressive regulatory T-cells. We could confirm that Kit-M significantly increased frequencies of (mature) dendritic cells (DC) and DC_leu from leukemic whole blood (WB) without induction of blast proliferation. After mixed lymphocyte culture (MLC) with patients' T-cells we confirmed that DC_leu mediated leukemia-specific responses- going along with activated and leukemia-specific T- and NK-cells in an intracellular cytokine staining assay (ICS) and a degranulation assay (Deg)- resulted in an increased anti-leukemic cytotoxicity (Cytotoxicity Fluorolysis Assay = CTX). We could demonstrate that (leukemia-specific) CD4⁺ and CD8⁺ regulatory T-cell population (T_reg) decreased significantly after MLC compared to controls. We found significant positive correlations of leukemia-specific CD3⁺CD4⁺ cells with frequencies of (mature) DC_leu. Achieved anti-leukemic cytotoxicity correlated significantly positive with leukemia-specific CD3⁺CD8⁺ cells and significantly negatively with (leukemia-specific) T_reg. In summary we demonstrate that immunesuppressive (leukemia-specific) regulatory T-cells are significantly downregulated after Kit-M triggered MLC- going along with a (reinstalled) antileukemic reactivity of the immune system (as demonstrated with functional assays ICS, Deg, CTX).

Impact of Early ARV Initiation on Relative Proportions of Effector and Regulatory CD8 T Cell in Mesenteric Lymph Nodes and Peripheral Blood During Acute SIV Infection of Rhesus Macaques

CD8 T cells are key players in the clearance of human immunodeficiency virus (HIV)-infected cells, such that CD8 T-cell dysfunction contributes to viral persistence despite antiretroviral (ARV) therapy. Mesenteric lymph nodes (MLNs) are major sites of gut mucosal immunity. While different CD8 T cell subsets such as CD8 alpha-alpha (CD8αα), CD8 alpha-beta (CD8αβ), CD8 regulatory T cells (Treg), and mucosa-associated invariant T cells (MAIT) are present in the gut and exhibit distinct functions, their dynamics remain poorly understood due to the lack of accessibility to these tissues in humans. We thus assessed CD8 T cells in MLNs versus peripheral blood in simian immunodeficiency virus (SIV)-infected rhesus macaques (RMs) following early ARV therapy initiation. SIV infection was associated with an increase over time of both CD8αβ and CD8αα T cells in the blood and MLNs, whereas early ARV initiation significantly decreased the frequencies of CD8αα but not CD8αβ T cells in MLNs. A significant decrease in the expression of chemokine receptors CCR6 and CXCR3 by CD8 T cells, which are essential for T-cell trafficking to the inflammatory sites, was observed in chronically SIV-infected RMs. Surprisingly, while MAIT cells are increased in ARV-treated RMs, their frequencies in MLN are extremely low and were not impacted by ARV. The acute infection resulted in an early CD39⁺FoxP3⁺ CD8 Tregs increase in both compartments, which was normalized after early ARV. Frequencies of CD8 Treg cells were positively correlated with frequencies of CD4 Tregs and accordingly negatively correlated with the Th17/Treg ratio in the blood but not in MLNs. Overall, our results underscore the difference in CD8 T-cell subset dynamics in the blood and MLNs.

IMPORTANCE Changes in CD8 T-cell subsets during acute SIV/HIV infections and following early ARV initiation in gut lymphoid tissues are poorly understood. Using an acute SIV infection model in rhesus macaques, we assessed the impact of early ARV, initiated 4 days postinfection, on relative proportions of CD8 T-cell subsets in MLNs compared to blood. We found that acute SIV infection and early ARV initiation differentially affect the distribution of effector CD8 T cells, CD8 MAIT cells, and CD8 Tregs in MLNs compared to blood. Overall, early ARV initiation maintains the frequency of effector CD8 T cells while reducing immunosuppressive CD39⁺ CD8 Tregs. Our study provides deeper insight into the dynamics of the CD8 T-cell compartment in gut mucosal immune surveillance during acute SIV infection and following early ARV initiation.

Simultaneous disruption of circulating miR-21 and cytotoxic T lymphocytes (CTLs): Prospective diagnostic and prognostic markers for esophageal squamous cell carcinoma (ESCC)

BACKGROUND

Esophageal squamous cell carcinoma (ESCC) as the most prominent type of esophageal cancer (EC) in developing countries encompasses a substantial contribution of cancer-related mortalities and morbidities. Cytotoxic T lymphocytes (CTLs) are the major subset of effector T cells against cancer. However, the microRNAs involved in the development and regulation of CTLs could be disrupted in cancers such as EC.

METHODS

Here, we evaluated the population of IL-10, TGF-β, IFN-γ, and IL-17a-producing CD3+CD8+ T cells, their association with the circulating levels of miR-21 and miR-29b, and their diagnostic and/or prognostic (after 160 weeks of follow-up) utilities in 34 ESCC patients (12 newly diagnosed: ND, 24 under-treatment: UT) and 34 matched healthy donors.

RESULTS

The population of IL-10 and TGF-β-producing CTLs (CD8+ Tregs) were considerably expanded, in addition to the overexpression of miR-21 in both groups (ND and UT) of ESCC patients, while the frequency of Tc17 and CD8+ Treg cells increased only in UT patients. The expression means of TGF-β and IL-10 in CTLs were considered to be excellent biomarkers (1 ≥ area under the curve: AUC ≥0.9) in distinguishing ESCC patients and associated subgroups from healthy subjects. Moreover, the lower expressions of TGF-β, IL-17a, IL-10, and IFN-γ in CTLs were associated with ESCC better prognosis.

CONCLUSIONS

The association between the impaired function of CD3+ CD8+ T cell subsets and miR-21 expression could be introduced as novel therapeutic targets and powerful diagnostic and prognostic markers for ESCC.

The TNF-α/TNFR2 Pathway: Targeting a Brake to Release the Anti-tumor Immune Response

Newly discovered anti-cancer immunotherapies, such as immune checkpoint inhibitors and chimeric antigen receptor T cells, focus on spurring the anti-tumor effector T cell (Teff) response. Although such strategies have already demonstrated a sustained beneficial effect in certain malignancies, a substantial proportion of treated patients does not respond. CD4⁺FOXP3⁺ regulatory T cells (Tregs), a suppressive subset of T cells, can impair anti-tumor responses and reduce the efficacy of currently available immunotherapies. An alternative view that has emerged over the last decade proposes to tackle this immune brake by targeting the suppressive action of Tregs on the anti-tumoral response. It was recently demonstrated that the tumor necrosis factor alpha (TNF-α) tumor necrosis factor receptor 2 (TNFR2) is critical for the phenotypic stabilization and suppressive function of human and mouse Tregs. The broad non-specific effects of TNF-α infusion in patients initially led clinicians to abandon this signaling pathway as first-line therapy against neoplasms. Previously unrecognized, TNFR2 has emerged recently as a legitimate target for anti-cancer immune checkpoint therapy. Considering the accumulation of pre-clinical data on the role of TNFR2 and clinical reports of TNFR2⁺ Tregs and tumor cells in cancer patients, it is now clear that a TNFR2-centered approach could be a viable strategy, once again making the TNF-α pathway a promising anti-cancer target. Here, we review the role of the TNFR2 signaling pathway in tolerance and the equilibrium of T cell responses and its connections with oncogenesis. We analyze recent discoveries concerning the targeting of TNFR2 in cancer, as well as the advantages, limitations, and perspectives of such a strategy.

Complement factor B regulates cellular senescence and is associated with poor prognosis in pancreatic cancer

BACKGROUND

The interplay between cancer cells and stromal components, including soluble mediators released from cancer cells, contributes to the progression of pancreatic ductal adenocarcinoma (PDAC). Here, we set out to identify key secreted proteins involved in PDAC progression.

METHODS

We performed secretome analyses of culture media of mouse pancreatic intraepithelial neoplasia (PanIN) and PDAC cells using Stable Isotope Labeling by Amino acid in Cell culture (SILAC) with click chemistry and liquid chromatography-mass spectrometry (LC-MS/MS). The results obtained were verified in primary PDAC tissue samples and cell line models.

RESULTS

Complement factor B (CFB) was identified as one of the robustly upregulated proteins, and found to exhibit elevated expression in PDAC cells compared to PanIN cells. Endogenous CFB knockdown by a specific siRNA dramatically decreased the proliferation of PDAC cells, PANC-1 and MIA PaCa-II. CFB knockdown induced increases in the number of senescence-associated-β-galactosidase (SA-β-gal) positive cells exhibiting p21 expression upregulation, which promotes cellular senescence with cyclinD1 accumulation. Furthermore, CFB knockdown facilitated downregulation of proliferating cell nuclear antigen and led to cell cycle arrest in the G1 phase in PDAC cells. Using immunohistochemistry, we found that high stromal CFB expression was associated with unfavorable clinical outcomes with hematogenous dissemination after surgery in human PDAC patients. Despite the presence of enriched CD8+ tumor infiltrating lymphocytes in the PDAC tumor microenvironments, patients with a high stromal CFB expression exhibited a significantly poorer prognosis compared to those with a low stromal CFB expression. Immunofluorescence staining revealed a correlation between stromal CFB expression in the tumor microenvironment and an enrichment of immunosuppressive regulatory T-cells (Tregs), myeloid-derived suppressor cells (MDSCs) and tumor-associated macrophages (TAMs). We also found that high stromal CFB expression showed a positive correlation with high CD8+/Foxp3+ Tregs populations in PDAC tissues.

CONCLUSIONS

Our data indicate that CFB, a key secreted protein, promotes proliferation by preventing cellular senescence and is associated with immunological tumor promotion in PDAC. These findings suggest that CFB may be a potential target for the treatment of PDAC.

Immune Equilibrium Depends on the Interaction Between Recognition and Presentation Landscapes

In this review, we described the structure and organization of antigen-recognizing repertoires of B and T cells from the standpoint of modern immunology. We summarized the latest advances in bioinformatics analysis of sequencing data from T and B cell repertoires and also presented contemporary ideas about the mechanisms of clonal diversity formation at different stages of organism development. At the same time, we focused on the importance of the allelic variants of the HLA genes and spectra of presented antigens for the formation of T-cell receptors (TCR) landscapes. The main idea of this review is that immune equilibrium and proper functioning of immunity are highly dependent on the interaction between the recognition and the presentation landscapes of antigens. Certain changes in these landscapes can occur during life, which can affect the protective function of adaptive immunity. We described some mechanisms associated with these changes, for example, the conversion of effector cells into regulatory cells and vice versa due to the trans-differentiation or bystander effect, changes in the clonal organization of the general TCR repertoire due to homeostatic proliferation or aging, and the background for the altered presentation of some antigens due to SNP mutations of MHC, or the alteration of the presenting antigens due to post-translational modifications. The authors suggest that such alterations can lead to an increase in the risk of the development of oncological and autoimmune diseases and influence the sensitivity of the organism to different infectious agents.

Resveratrol for targeting the tumor microenvironment and its interactions with cancer cells

Tumor resistance to therapy modalities is one of the major challenges to the eradication of cancer cells and complete treatment. Tumor includes a wide range of cancer and non-cancer cells that play key roles in the proliferation of cancer cells and suppression of anti-tumor immunity. For overcoming tumor resistance to therapy, it is important to have in-depth knowledge relating to intercellular communications within the tumor microenvironment (TME). TME includes various types of immune cells such as CD4 + T lymphocytes, cytotoxic T lymphocytes (CTLs), natural killer (NK) cells, macrophages, and T regulatory cells (Tregs). Furthermore, some non-immune cells like cancer stem cells (CSCs), mesenchymal stem cells (MSCs), and cancer-associated fibroblasts (CAFs) are involved in the promotion of tumor growth. The interactions between these cells with cancer cells play a key role in tumor growth or inhibition. Resveratrol as a natural agent has shown the ability to modulate the immune system to potentiate anti-tumor immunity and also help to attenuate cancer cells and CSCs resistance. Thus, this review explains how resveratrol can modulate interactions within TME.

Potential Impact of Human Cytomegalovirus Infection on Immunity to Ovarian Tumours and Cancer Progression

Ovarian cancer (OC) is one of the most common, and life-threatening gynaecological cancer affecting females. Almost 75% of all OC cases are diagnosed at late stages, where the 5-year survival rate is less than 30%. The aetiology of the disease is still unclear, and there are currently no screening method nor effective treatment strategies for the advanced disease. A growing body of evidence shows that human cytomegalovirus (HCMV) infecting more than 50% of the world population, may play a role in inducing carcinogenesis through its immunomodulatory activities. In healthy subjects, the primary HCMV infection is essentially asymptomatic. The virus then establishes a life-long chronic latency primarily in the hematopoietic progenitor cells in the bone marrow, with periodic reactivation from latency that is often characterized by high levels of circulating pro-inflammatory cytokines. Currently, infection-induced chronic inflammation is considered as an essential process for OC progression and metastasis. In line with this observation, few recent studies have identified high expressions of HCMV proteins on OC tissue biopsies that were associated with poor survival outcomes. Active HCMV infection in the OC tumour microenvironment may thus directly contribute to OC progression. In this review, we highlight the potential impact of HCMV infection-induced immunomodulatory effects on host immune responses to OC that may promote OC progression.

Heterogeneity of T Cells in Atherosclerosis Defined by Single-Cell RNA-Sequencing and Cytometry by Time of Flight

The infiltration and accumulation of pro- and anti-inflammatory leukocytes within the intimal layer of the arterial wall is a hallmark of developing and progressing atherosclerosis. While traditionally perceived as macrophage- and foam cell-dominated disease, it is now established that atherosclerosis is a partial autoimmune disease that involves the recognition of peptides from ApoB (apolipoprotein B), the core protein of LDL (low-density lipoprotein) cholesterol particles, by CD4+ T-helper cells and autoantibodies against LDL and ApoB. Autoimmunity in the atherosclerotic plaque has long been understood as a pathogenic T-helper type-1 driven response with proinflammatory cytokine secretion. Recent developments in high-parametric cell immunophenotyping by mass cytometry, single-cell RNA-sequencing, and in tools exploring antigen-specificity have established the existence of several unforeseen layers of T-cell diversity with mixed TH1 and T regulatory cells transcriptional programs and unpredicted fates. These findings suggest that pathogenic ApoB-reactive T cells evolve from atheroprotective and immunosuppressive CD4+ T regulatory cells that lose their protective properties over time. Here, we discuss T-cell heterogeneity in atherosclerosis with a focus on plasticity, antigen-specificity, exhaustion, maturation, tissue residency, and its potential use in clinical prediction.

Advances in the treatment of graft-versus-host disease with immunomodulatory cells

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) has been widely used to treat hematological malignancies and genetic diseases. Graft-versus-host disease (GVHD) induced by donor immune system is the most common complication, contributing to severe morbidity and mortality after allo-HSCT. Currently, in terms of the prevention and treatment of GVHD, the major first-line therapeutic drugs are corticosteroids. However, most patients with systemic corticosteroid treatment are prone to steroid-refractory and poor prognosis. The use of several immune cells including Tregs, Bregs and mesenchymal stromal cells (MSCs) as an alternative on prevention or therapy of GVHD has been demonstrated to be beneficial. However, there are still many defects to a certain degree. Based on immune cells, it is promising to develop new and better approaches to improve GVHD. In this article, we will review the current advance of immune cells (Tregs, Bregs, MSCs) with negative regulation in the treatment of GVHD and present emerging strategies for the prevention and treatment of GVHD by other immune regulatory cells and chimeric antigen receptor (CAR) Tregs. In addition, these new therapeutic options need to be further evaluated in well-designed prospective multicenter trials to determine the optimal treatment for GVHD patients and improve their prognosis.

Immunoregulatory Cells in Myasthenia Gravis

Myasthenia gravis (MG) is a T cell-dependent, B-cell mediated autoimmune disease caused by antibodies against the nicotinic acetylcholine receptor or other components of the post-synaptic muscle endplate at the neuromuscular junction. These specific antibodies serve as excellent biomarkers for diagnosis, but do not adequately substitute for clinical evaluations to predict disease severity or treatment response. Several immunoregulatory cell populations are implicated in the pathogenesis of MG. The immunophenotype of these populations has been well-characterized in human peripheral blood. CD4⁺FoxP3⁺ regulatory T cells (Tregs) are functionally defective in MG, but there is a lack of consensus on whether they show numerical perturbations. Myeloid-derived suppressor cells (MDSCs) have also been explored in the context of MG. Adoptive transfer of CD4⁺FoxP3⁺ Tregs or MDSCs suppresses ongoing experimental autoimmune MG (EAMG), a rodent model of MG, suggesting a protective role of both populations in this disease. An imbalance between follicular Tregs and follicular T helper cells is found in untreated MG patients, correlating with disease manifestations. There is an inverse correlation between the frequency of circulating IL-10–producing B cells and clinical status in MG patients. Taken together, both functional and numerical defects in various populations of immunoregulatory cells in EAMG and human MG have been demonstrated, but how they relate to pathogenesis and whether these cells can serve as biomarkers of disease activity in humans deserve further exploration.

Suppression of Chlamydial Pathogenicity by Nonspecific CD8+ T Lymphocytes

Chlamydia trachomatis, a leading infectious cause of tubal infertility, induces upper genital tract pathology, such as hydrosalpinx, which can be modeled with Chlamydia muridarum infection in mice. Following C. muridarum inoculation, wild-type mice develop robust hydrosalpinx, but OT1 mice fail to do so because their T cell receptors are engineered to recognize a single ovalbumin epitope (OVA457-462). These observations have demonstrated a critical role of Chlamydia-specific T cells in chlamydial pathogenicity. In the current study, we have also found that OT1 mice can actively inhibit chlamydial pathogenicity. First, depletion of CD8+ T cells from OT1 mice led to the induction of significant hydrosalpinx by Chlamydia, indicating that CD8+ T cells are necessary to inhibit chlamydial pathogenicity. Second, adoptive transfer of CD8+ T cells from OT1 mice to CD8 knockout mice significantly reduced chlamydial induction of hydrosalpinx, demonstrating that OT1 CD8+ T cells are sufficient for attenuating chlamydial pathogenicity in CD8 knockout mice. Finally, CD8+ T cells from OT1 mice also significantly inhibited hydrosalpinx development in wild-type mice following an intravaginal inoculation with Chlamydia Since T cells in OT1 mice are engineered to recognize only the OVA457-462 epitope, the above observations have demonstrated a chlamydial antigen-independent immune mechanism for regulating chlamydial pathogenicity. Further characterization of this mechanism may provide information for developing strategies to reduce infertility-causing pathology induced by infections.

CTLA-4 immunotherapy exposes differences in immune response along with different tumor progression in colorectal cancer

Tumor growth is accompanied by a changing tumor microenvironment and mutations that increase the resistance to therapy. Here, we used syngeneic models to evaluate the drug response of tumors of the same type of different sizes. We used the in vivo efficacy and Ki-67 immunohistochemistry (IHC) assay to assess the difference in responses in response to treatment with the same concentration of anti-CTLA-4. Flow cytometry analysis revealed changes in the immune subpopulations changes the spleen, peripheral blood, lymph node, and tumor tissue across different tumor growth phases. For example, naive CD4+T, CD4+TCM, CD8+TEM, T, B, Treg, CD8+TCM exhibited different percentages depending on the specific immune organ. To further expose the changes in the immune microenvironment, the level of expression of PD-1 and CTLA-4 showed statistically significant difference in related subsets for each four immune tissues in different tumor sizes. In addition, the ratios of CD4 + Teff/ CD4 + Treg and CD8 + T/Treg in corresponding immune tissue were also associated with statistically significant differences alongside tumor growth in different animal models. These results reveal the ongoing changes in the immune microenvironment during tumor progression and anti-CTLA-4 antibody immunotherapy effect depends on the expression level of immune factors.

Decreased cytotoxic T cells and TCR clonality in organ transplant recipients with squamous cell carcinoma

T-cell landscape differences between cutaneous squamous cell carcinoma (cSCC) tumors in immune competent (SCC in IC) and immunocompromised organ transplant recipients (TSCC in OTR) are unclear. We developed an analytical method to define tumor infiltrating lymphocyte (TIL) phenotype in cSCC from immune competent and immune suppressed patients using single-cell TCR sequencing and gene expression data. TSCC exhibits reduced proportions of cytotoxic and naïve TILs and similar numbers of regulatory TILs. Fewer, more heterogeneous TCR clonotypes are observed in TIL from OTR. Most TCR sequences for top ten clonotypes correspond to known antigens, while 24% correspond to putative neoantigens. OTR show increased cSCC events over 12 months possibly due to reduced cytotoxic T-cells. Our novel method of barcoding CD8+ T-cells is the first providing gene expression and TCR sequences in cSCC. Knowledge regarding putative antigens recognized by TCRs with phenotypic function of T-cells bearing those TCRs could facilitate personalized cSCC treatments.

Exposure of pregnant rats to staphylococcal enterotoxin B attenuates the response of increased Tregs to re-exposure to SEB in the thymus of adult offspring

Regulatory T cells (Tregs) play an essential role during homeostasis and tolerance of the immune system. Based on our previous study that exposure of pregnant rats to staphylococcal enterotoxin B (SEB) can alter the percentage of CD4/CD8 subsets in the thymus of the offspring, in this study, we focus on the influence of exposure of pregnant rats to SEB on number, function and response of Tregs in the thymus of the offspring. Pregnant rats at gestational day of 16 were intravenously injected with 15 μg SEB and the thymuses of the neonatal and adult offspring were harvested for this study. We found that exposure of pregnant rats to SEB could significantly increase the absolute number of Tregs and the FoxP3 expression level in the thymus of not only neonatal but also adult offspring. Re-exposure of adult offspring to SEB remarkably reduced the suppressive capacity of Tregs to CD4⁺ T cells and the expression levels of TGF-β and IL-10 in the thymus, but had no effect on production of IL-4 and IFN-γ. Furthermore, it also notedly decreased the absolute number of Tregs and the FoxP3 expression level. These data suggest that prenatal exposure of pregnant rats to SEB attenuates the response of increased Tregs to re-exposure to SEB in the thymus of adult offspring.

Immune co-culture cell microarray - a feasible tool for high-throughput functional investigation of lymphocyte-cancer interactions

Omics analyses often result in dozens to hundreds of potential targets, requiring validation for their biological relevance. Current high-throughput functional investigation methods are frequently labor-intensive, expensive, and display low reproducibility. The Immune Co-Culture Cell Microarray (ICCM) is a formalin-fixed paraffin-embedded cell block microarray based on co-cultures of patient-derived tumor-infiltrating lymphocytes and their autologous melanoma cells. Each ICCM slide represents the same experiment and can be stained using standard immunohistochemistry and immunofluorescence techniques. Functional dynamics assessment of both proteins and microRNAs using ICCM stained slides demonstrated similar findings to flow cytometry assays and to previously published patient-derived biopsy reports.

Impaired lipid biosynthesis hinders anti-tumor efficacy of intratumoral iNKT cells

Dysfunction of invariant natural killer T (iNKT) cells in tumor microenvironment hinders their anti-tumor efficacy, and the underlying mechanisms remain unclear. Here we report that iNKT cells increase lipid biosynthesis after activation, and that is promoted by PPARγ and PLZF synergically through enhancing transcription of Srebf1. Among those lipids, cholesterol is required for the optimal IFN-γ production from iNKT cells. Lactic acid in tumor microenvironment reduces expression of PPARγ in intratumoral iNKT cells and consequently diminishes their cholesterol synthesis and IFN-γ production. Importantly, PPARγ agonist pioglitazone, a thiazolidinedione drug for type 2 diabetes, successfully restores IFN-γ production in tumor-infiltrating iNKT cells from both human patients and mouse models. Combination of pioglitazone and alpha-galactosylceramide treatments significantly enhances iNKT cell-mediated anti-tumor immune responses and prolongs survival of tumor-bearing mice. Our studies provide a strategy to augment the anti-tumor efficacy of iNKT cell-based immunotherapies via promoting their lipid biosynthesis.

Lipid metabolism has been linked to iNKT function largely as it impacts processing and presentation of lipids they recognize. Here the authors show that iNKT-intrinsic lipid biosynthesis is important for their function but is impaired in tumors, and its restoration with PPARγ agonist drugs promotes anti-tumor iNKT response.

Enhanced Anti-melanoma Efficacy of a Pim-3-Targeting Bifunctional Small Hairpin RNA via Single-Stranded RNA-Mediated Activation of Plasmacytoid Dendritic Cells

Melanoma is the most serious type of skin cancer. The immunosuppressive tumor microenvironment and aberrant expression of some proto-oncogenes are the main cause of melanoma development. We have constructed a single-stranded RNA (ssRNA)–Pim-3–small hairpin RNA (shRNA) dual-function vector, which activates the toll-like receptor (TLR)7 to stimulate the antitumor immune response through ssRNA fragments and simultaneously silences the proto-oncogene Pim-3 to intensify apoptosis of the tumor cells via shRNA. Here, we found that therapy with the ssRNA-Pim-3-shRNA dual-function vector not only promotes the apoptosis and inhibits the proliferation of B16F10 melanoma cells by inhibiting the expression of Pim-3 but also enhances the activation of CD8⁺ T cells and natural killer (NK) cells and simultaneously reduces the proportion of intratumoral regulatory T cells (Tregs) and myeloid-derived suppressor cells (MDSCs). Together, these features effectively inhibit the growth of melanoma. Intriguingly, the bifunctional therapeutic effect that reverses the tumor immunosuppressive microenvironment is dependent on the activation of plasmacytoid dendritic cells (pDCs) and the secretion of type I interferon (IFN). Our study suggests that ssRNA-Pim-3-shRNA dual-function therapy is expected to become a promising therapeutic strategy for melanoma and other solid tumors with immunosuppressive microenvironment.

A Review of the Potential Role of Human Cytomegalovirus (HCMV) Infections in Breast Cancer Carcinogenesis and Abnormal Immunity

Previously recognized classical human onco-viruses can regulate complex neoplastic events, and are estimated to play a role during carcinogenesis in 15-20% of cancer cases. Although the DNA and gene products of several viruses have been found in breast tumors, none of the classical onco-viruses have definitely been linked to the initiation of breast cancer. However, recent evidence shows that human cytomegalovirus (HCMV) gene products are found in >90% of tumors and metastases of breast cancers, and their increased expression can be correlated to a more aggressive breast cancer phenotype. Supporting the active role of HCMV in breast cancer, a specific HCMV strain, HCMV-DB, was recently shown to exert oncogenic transformational activity in breast epithelial cells in vitro, and to give rise to fast-growing, triple-negative breast tumors when injected into immune deficient mice. The same observation holds true for clinical studies implying increased HCMV protein expression in triple negative breast cancer biopsies. In addition to functionally being able to hijack tumor-promoting cellular events, HCMV is known to exhibit a wide range of immunosuppressive effects, which can have radical impact on the tumor microenvironment. HCMV infected cells can avoid recognition and elimination by the immune system by orchestrating polarization of immunosuppressive type II macrophages, preventing antigen presentation, by expressing T cell inhibitory molecules, and possibly, by the induction of regulatory T (Treg) cell responses. These actions would be especially deleterious for the antigenic activation and proliferation of tumor specific CD8⁺ cytotoxic T lymphocytes (CTLs), whose effector functions have recently been targeted by successful, experimental immunotherapy protocols. The recognition of alternative causes and drivers of breast cancer is a pivotal research topic for the development of diagnostics and novel, effective preventive and therapeutic strategies targeting both tumor cells and their microenvironments.

Phenotypic characterisation of regulatory T cells in dogs reveals signature transcripts conserved in humans and mice

Regulatory T cells (Tregs) are a double-edged regulator of the immune system. Aberrations of Tregs correlate with pathogenesis of inflammatory, autoimmune and neoplastic disorders. Phenotypically and functionally distinct subsets of Tregs have been identified in humans and mice on the basis of their extensive portfolios of monoclonal antibodies (mAb) against Treg surface antigens. As an important veterinary species, dogs are increasingly recognised as an excellent model for many human diseases. However, insightful study of canine Tregs has been restrained by the limited availability of mAb. We therefore set out to characterise CD4+CD25high T cells isolated ex vivo from healthy dogs and showed that they possess a regulatory phenotype, function, and transcriptomic signature that resembles those of human and murine Tregs. By launching a cross-species comparison, we unveiled a conserved transcriptomic signature of Tregs and identified that transcript hip1 may have implications in Treg function.

The Tolerogenic Function of Regulatory T Cells in Pregnancy and Cancer

Regulatory T cells, a subpopulation of suppressive T cells, are potent mediators of self-tolerance and essential for the suppression of triggered immune responses. The immune modulating capacity of these cells play a major role in both transplantation, autoimmune disease, allergy, cancer and pregnancy. During pregnancy, low numbers of regulatory T cells are associated with pregnancy failure and pregnancy complications such as pre-eclampsia. On the other hand, in cancer, low numbers of immunosuppressive T cells are correlated with better prognosis. Hence, maternal immune tolerance toward the fetus during pregnancy and the escape from host immunosurveillance by cancer seem to be based on similar immunological mechanisms being highly dependent on the balance between immune activation and suppression. As regulatory T cells hold a crucial role in several biological processes, they may also be promising subjects for therapeutic use. Especially in the field of cancer, cell therapy and checkpoint inhibitors have demonstrated that immune-based therapies have a very promising potential in treatment of human malignancies. However, these therapies are often accompanied by adverse autoimmune side effects. Therefore, expanding the knowledge to recognize the complexities of immune regulation pathways shared across different immunological scenarios is extremely important in order to improve and develop new strategies for immune-based therapy. The intent of this review is to highlight the functional characteristics of regulatory T cells in the context of mechanisms of immune regulation in pregnancy and cancer, and how manipulation of these mechanisms potentially may improve therapeutic options.