Suppressive IL-17A+Foxp3+ and ex-Th17 IL-17AnegFoxp3+ Treg cells are a source of tumour-associated Treg cells

Curcumin as a regulator of Th17 cells: Unveiling the mechanisms

Curcumin, a polyphenol natural product derived from turmeric, possesses diverse pharmacological effects due to its interactions with various cells and molecules. Recent studies have highlighted its immunomodulatory properties, including its impact on immune cells and mediators involved in immune responses. Th17 cells play a crucial role in promoting immune responses against extracellular pathogens by recruiting neutrophils and inducing inflammation. These cells produce inflammatory cytokines such as TNF-α, IL-21, IL-17A, IL-23, IL-17F, IL-22, and IL-26. Curcumin has been shown to significantly inhibit the proliferation of Th17 cells and reduce the production of inflammatory cytokines, including TNF-α, IL-22, and IL-17. This review aims to assess the effectiveness of curcumin and its underlying mechanisms in modulating Th17 cells.

Stability and plasticity of regulatory T cells in health and disease

The mechanisms that negatively regulate inflammation upon a pathogenic stimulus are crucial for the maintenance of tissue integrity and organ function. T regulatory cells are one of the main drivers in controlling inflammation. The ability of T regulatory cells to adapt to different inflammatory cues and suppress inflammation is one of the relevant features of T regulatory cells. During this process, T regulatory cells express different transcription factors associated with their counterparts, Th helper cells, including Tbx21, GATA-3, Bcl6, and Rorc. The acquisition of this transcription factor helps the T regulatory cells to suppress and migrate to the different inflamed tissues. Additionally, the T regulatory cells have different mechanisms that preserve stability while acquiring a particular T regulatory cell subtype. This review focuses on describing T regulatory cell subtypes and the mechanisms that maintain their identity in health and diseases.

Interleukin-17 directly stimulates tumor infiltrating Tregs to prevent cancer development

Background

Interleukin-17 (IL-17) family cytokines promote protective inflammation for pathogen resistance, but also facilitate autoimmunity and tumor development. A direct signal of IL-17 to regulatory T cells (Tregs) has not been reported and may help explain these dichotomous responses.

Methods

We generated a conditional knockout of Il17ra in Tregs by crossing Foxp3-YFP-Cre mice to Il17ra-flox mice (Il17ra ΔTreg mice). Subsequently, we adoptively transferred bone marrow cells from Il17ra ΔTreg mice to a mouse model of sporadic colorectal cancer (Cdx2-Cre +/Apc F/+), to selectively ablate IL-17 direct signaling on Tregs in colorectal cancer. Single cell RNA sequencing and bulk RNA sequencing were performed on purified Tregs from mouse colorectal tumors, and compared to those of human tumor infiltrating Treg cells.

Results

IL-17 Receptor A (IL-17RA) is expressed in Tregs that reside in mouse mesenteric lymph nodes and colon tumors. Ablation of IL-17RA, specifically in Tregs, resulted in increased Th17 cells, and exacerbated tumor development. Mechanistically, tumor-infiltrating Tregs exhibit a unique gene signature that is linked to their activation, maturation, and suppression function, and this signature is in part supported by the direct signaling of IL-17 to Tregs. To study pathways of Treg programming, we found that loss of IL-17RA in tumor Tregs resulted in reduced RNA splicing, and downregulation of several RNA binding proteins that are known to regulate alternative splicing and promote Treg function.

Conclusion

IL-17 directly signals to Tregs and promotes their maturation and function. This signaling pathway constitutes a negative feedback loop that controls cancer-promoting inflammation in CRC.

Inflammation-related molecular signatures involved in the anticancer activities of brigatinib as well as the prognosis of EML4-ALK lung adenocarcinoma patient

Although ALK tyrosine kinase inhibitors (ALK-TKIs) have shown remarkable benefits in EML4-ALK positive NSCLC patients compared to conventional chemotherapy, the optimal sequence of ALK-TKIs treatment remains unclear due to the emergence of primary and acquired resistance and the lack of potential prognostic biomarkers. In this study, we systematically explored the validity of sequential ALK inhibitors (alectinib, lorlatinib, crizotinib, ceritinib and brigatinib) for a heavy-treated patient with EML4-ALK fusion via developing an in vitro and in vivo drug testing system based on patient-derived models. Based on the patient-derived models and clinical responses of the patient, we found that crizotinib might inhibit proliferation of EML4-ALK positive tumors resistant to alectinib and lorlatinib. In addition, NSCLC patients harboring the G1269A mutation, which was identified in alectinib, lorlatinib and crizotinib-resistant NSCLC, showed responsiveness to brigatinib and ceritinib. Transcriptomic analysis revealed that brigatinib suppressed the activation of multiple inflammatory signaling pathways, potentially contributing to its anti-tumor activity. Moreover, we constructed a prognostic model based on the expression of IL6, CXCL1, and CXCL5, providing novel perspectives for predicting prognosis in EML4-ALK positive NSCLC patients. In summary, our results delineate clinical responses of sequential ALK-TKIs treatments and provide insights into the mechanisms underlying the superior effects of brigatinib in patients harboring ALKG1269A mutation and resistant towards alectinib, lorlatinib and crizotinib. The molecular signatures model based on the combination of IL6, CXCL1 and CXCL5 has the potential to predict prognosis of EML4-ALK positive NSCLC patients.

Immune modulation in transplant medicine: a comprehensive review of cell therapy applications and future directions

Balancing the immune response after solid organ transplantation (SOT) and vascularized composite allotransplantation (VCA) remains an ongoing clinical challenge. While immunosuppressants can effectively reduce acute rejection rates following transplant surgery, some patients still experience recurrent acute rejection episodes, which in turn may progress to chronic rejection. Furthermore, these immunosuppressive regimens are associated with an increased risk of malignancies and metabolic disorders. Despite significant advancements in the field, these IS related side effects persist as clinical hurdles, emphasizing the need for innovative therapeutic strategies to improve transplant survival and longevity. Cellular therapy, a novel therapeutic approach, has emerged as a potential pathway to promote immune tolerance while minimizing systemic side-effects of standard IS regiments. Various cell types, including chimeric antigen receptor T cells (CAR-T), mesenchymal stromal cells (MSCs), regulatory myeloid cells (RMCs) and regulatory T cells (Tregs), offer unique immunomodulatory properties that may help achieve improved outcomes in transplant patients. This review aims to elucidate the role of cellular therapies, particularly MSCs, T cells, Tregs, RMCs, macrophages, and dendritic cells in SOT and VCA. We explore the immunological features of each cell type, their capacity for immune regulation, and the prospective advantages and obstacles linked to their application in transplant patients. An in-depth outline of the current state of the technology may help SOT and VCA providers refine their perioperative treatment strategies while laying the foundation for further trials that investigate cellular therapeutics in transplantation surgery.

Lingual Denervation Improves the Efficacy of Anti-PD-1 Immunotherapy in Oral Squamous Cell Carcinomas by Downregulating TGFβ Signaling

PURPOSE

Intratumoral nerve infiltration relates to tumor progression and poor survival in oral squamous cell carcinoma (OSCC). How neural involvement regulates antitumor immunity has not been well characterized. This study aims to investigate molecular mechanisms of regulating tumor aggressiveness and impairing antitumor immunity by nerve-derived factors.

EXPERIMENTAL DESIGN

We performed the surgical lingual denervation in an immunocompetent mouse OSCC model to investigate its effect on tumor growth and the efficacy of anti-PD-1 immunotherapy. A trigeminal ganglion neuron and OSCC cell coculture system was established to investigate the proliferation, migration, and invasion of tumor cells and the PD-L1 expression. Both the neuron-tumor cell coculture in vitro model and the OSCC animal model were explored.

RESULTS

Lingual denervation slowed down tumor growth and improved the efficacy of anti-PD-1 treatment in the OSCC model. Coculturing with neurons not only enhanced the proliferation, migration, and invasion but also upregulated TGFβ-SMAD2 signaling and PD-L1 expression of tumor cells. Treatment with the TGFβ signaling inhibitor galunisertib reversed nerve-derived tumor aggressiveness and downregulated PD-L1 on tumor cells. Similarly, lingual denervation in vivo decreased TGFβ and PD-L1 expression and increased CD8+ T-cell infiltration and the expression of IFNγ and TNFα within tumor.

CONCLUSIONS

Neural involvement enhanced tumor aggressiveness through upregulating TGFβ signaling and PD-L1 expression in OSCC, while denervation of OSCC inhibited tumor growth, downregulated TGFβ signaling, enhanced activities of CD8+ T cells, and improved the efficacy of anti-PD-1 immunotherapy. This study will encourage further research focusing on denervation as a potential adjuvant therapeutic approach in OSCC.

SIGNIFICANCE

This study revealed the specific mechanisms for nerve-derived cancer progression and impaired antitumor immunity in OSCC, providing a novel insight into the cancer-neuron-immune network as well as pointing the way for new strategies targeting nerve-cancer cross-talk as a potential adjuvant therapeutic approach for OSCC.

Tozasertib activates anti-tumor immunity through decreasing regulatory T cells in melanoma

Although immune checkpoint therapy has significantly improved the prognosis of patients with melanoma, urgent attention still needs to be paid to the low patient response rates and the challenges of precisely identifying patients before treatment. Therefore, it is crucial to investigate novel immunosuppressive mechanisms and targets in the tumor microenvironment in order to reverse tumor immune escape. In this study, we found that the cell cycle checkpoint Aurora kinase B (AURKB) suppressed the anti-tumor immune response, and its inhibitor, Tozasertib, effectively activated T lymphocyte cytokine release in vitro and anti-tumor immunity in vivo. Tozasertib significantly inhibited melanoma xenograft tumor growth by decreasing the number of inhibitory CD4+ Treg cells in the tumors, which, in turn, activated CD8+ T cells. Single-cell analysis revealed that AURKB suppressed anti-tumor immunity by increasing MIF-CD74/CXCR4 signaling between tumor cells and lymphocytes. Our study suggests that AURKB is a newly identified anti-tumor immunity suppressor, whose inhibitors may be developed as novel anti-tumor immunity drugs and may have synergistic anti-melanoma effects with immune checkpoint therapies.

Sirtuin2 suppresses the polarization of regulatory T cells toward T helper 17 cells through repressing the expression of signal transducer and activator of transcription 3 in a mouse colitis model

INTRODUCTION

Regulatory T cells (Tregs) play an important role in inflammatory bowel diseases (IBDs) through modulating intestinal inflammation. However, the factors affecting Treg function and plasticity during IBD progression are not thoroughly disclosed. The current study aims to reveal new molecular mechanisms affecting Treg plasticity.

METHODS

A mouse strain, in which tdTomato and enhanced green fluorescent protein were under the control of the Foxp3 promoter and Il17a promoter, was established and subjected to colitis induction with dextran sulfate sodium. The existence of Tregs and IL-17-expressing Tregs (i.e., Treg/T helper 17 [Th17] cells) were observed and sorted from the spleen, mesenteric lymph nodes, and lamina propria by flow cytometry, followed by measuring Sirtuin2 (Sirt2) expression using quantitative reverse transcription polymerase chain reaction and Immunoblotting. Lentivirus-induced Sirt2 silencing was applied to determine the impact of Sirt2 on Treg polarization to Treg/Th17 cells and even Th17 cells. The effect of Sirt2 on Stat3 was analyzed by flow cytometry and immunoblotting.

RESULTS

Sirt2 was highly expressed in lamina propria Tregs and it moderately suppressed Foxp3 expression as well as the immunosuppressive function of Tregs. Surprisingly, lentivirus-mediated Sirt2 silencing promoted the generation of Treg/Th17 cells out of Tregs. Sirt2 silencing also enhanced the generation of Th17 cells out of Tregs under the Th17 induction condition. Furthermore, Sirt2 inhibited Th17 induction by suppressing the protein level of the signal transducer and activator of transcription 3.

CONCLUSION

Sirt2 suppresses Treg function but also inhibits Treg polarization toward Treg/Th17 cells and Th17 cells. The ultimate effect of Sirt2 on colitis might depend on the balance among Tregs, Treg/Th17 cells, and Th17 cells.

Heterogeneity and subtypes of CD4+ regulatory T cells: implications for tumor therapy

In the conventional view, CD4+ regulatory T cell (Treg) represents a subset of lymphocytes that involve the perception and negative regulation of the immune response. CD4+Treg plays an important role in the maintenance of immune homeostasis and immune tolerance. However, recent studies have revealed that CD4+Treg do not suppress the immune response in some diseases, but promote inflammatory injury or inhibit tissue remodeling, suggesting the functional heterogeneity of CD4+Treg. Their involvement in tumor pathogenesis is more complex than previously understood. This article reviews the relevant research on the heterogeneity of CD4+Treg, subtype classification, and their relationship with tumor therapy.

Regulation of regulatory T cells and tumor-associated macrophages in gastric cancer tumor microenvironment

INTRODUCTION

Despite advancements in the methods for prevention and early diagnosis of gastric cancer (GC), GC continues to be the fifth in incidence among major cancers and the third most common cause of cancer-related death. The therapeutic effects of surgery and drug treatment are still unsatisfied and show notable differences according to the tumor microenvironment (TME) of GC.

METHODS

Through screening Pubmed, Embase, and Web of Science, we identified and summarized the content of recent studies that focus on the investigation of Helicobacter pylori (Hp) infection, regulatory T cells (Tregs), and tumor-associated macrophages (TAMs) in the TME of GC. Furthermore, we searched and outlined the clinical research progress of various targeted drugs in GC treatment including CTLA-4, PD-1\PD-L1, and VEGF/VEGFR.

RESULTS

In this review, the findings indicate that Hp infection causes local inflammation and leads to immunosuppressive environment. High Tregs infiltration in the TME of GC is associated with increased induction and recruitment; the exact function of infiltrated Tregs in GC was also affected by phenotypes and immunosuppressive molecules. TAMs promote the development and metastasis of tumors, the induction, recruitment, and function of TAMs in the TME of gastric cancer are also regulated by various factors.

CONCLUSION

Discussing the distinct tumor immune microenvironment (TIME) of GC can deepen our understanding on the mechanism of cancer immune evasion, invasion, and metastasis, help us to reduce the incidence of GC, and guide the innovation of new therapeutic targets for GC eventually.

Targeting PGLYRP1 promotes antitumor immunity while inhibiting autoimmune neuroinflammation

Co-inhibitory and checkpoint molecules suppress T cell function in the tumor microenvironment, thereby rendering T cells dysfunctional. Although immune checkpoint blockade is a successful treatment option for multiple human cancers, severe autoimmune-like adverse effects can limit its application. Here, we show that the gene encoding peptidoglycan recognition protein 1 (PGLYRP1) is highly coexpressed with genes encoding co-inhibitory molecules, indicating that it might be a promising target for cancer immunotherapy. Genetic deletion of Pglyrp1 in mice led to decreased tumor growth and an increased activation/effector phenotype in CD8+ T cells, suggesting an inhibitory function of PGLYRP1 in CD8+ T cells. Surprisingly, genetic deletion of Pglyrp1 protected against the development of experimental autoimmune encephalomyelitis, a model of autoimmune disease in the central nervous system. PGLYRP1-deficient myeloid cells had a defect in antigen presentation and T cell activation, indicating that PGLYRP1 might function as a proinflammatory molecule in myeloid cells during autoimmunity. These results highlight PGLYRP1 as a promising target for immunotherapy that, when targeted, elicits a potent antitumor immune response while protecting against some forms of tissue inflammation and autoimmunity.

Immunobiology of cancer stem cells and their immunoevasion mechanisms

Cancer stem cells (CSCs) defined as a small fraction of cells within malignancies have been isolated from tumors with different histological origins with stem related characteristics such as self-replicating potential, tumorigenesis, and therapy resistance. The dynamic communication between CSCs and tumor microenvironment particularly immune cells orchestrates their fate and plasticity as well as the patient outcome. According to recent evidence, it has been reported that they harness different immunological pathways to escape immunosurveillance and express aberrantly immunomodulatory agents or decreased levels of factors forming antigen presenting machinery (APM), subsequently followed by impaired antigen presentation and suppressed immune detection. As effective therapies are expected to be able to eradicate CSCs, mechanistic understanding of such interactions can provide insights into causes of therapy failure particularly in immunotherapy. Also, it can contribute to enhance the practical interventions against CSCs and their immunomodulatory features resulting in CSCs eradication and improving patient clinical outcome. The aim of this review is to explain the present knowledge regarding the immunobiology of CSCs and the immunoevasion mechanisms they use.

A clinically-relevant STING agonist restrains human TH17 cell inflammatory profile

The STING signaling pathway has gained attention over the last few years due to its ability to incite antimicrobial and antitumoral immunity. Conversely, in mouse models of autoimmunity such as colitis and multiple sclerosis, where TH17 cells are implicated in tissue inflammation, STING activation has been associated with the attenuation of immunogenic responses. In this line, STING was found to limit murine TH17 pro-inflammatory program in vitro. Here we demonstrate that 2'3'-c-di-AM(PS)2(Rp,Rp), a STING agonist that has been undergoing clinical trials for antitumor immunotherapy, activates the STING signalosome in differentiating human TH17 cells. Of particular interest, 2'3'-c-di-AM(PS)2(Rp,Rp) reduces IL-17A production and IL23R expression by human TH17 cells while it favors the generation of regulatory T (Treg) cells. These findings suggest that STING agonists may be promising approaches for treating human TH17-mediated chronic inflammation.

Lrig1-expression confers suppressive function to CD4+ cells and is essential for averting autoimmunity via the Smad2/3/Foxp3 axis

Regulatory T cells (Treg) are CD4+ T cells with immune-suppressive function, which is defined by Foxp3 expression. However, the molecular determinants defining the suppressive population of T cells have yet to be discovered. Here we report that the cell surface protein Lrig1 is enriched in suppressive T cells and controls their suppressive behaviors. Within CD4+ T cells, Treg cells express the highest levels of Lrig1, and the expression level is further increasing with activation. The Lrig1+ subpopulation from T helper (Th) 17 cells showed higher suppressive activity than the Lrig1- subpopulation. Lrig1-deficiency impairs the suppressive function of Treg cells, while Lrig1-deficient naïve T cells normally differentiate into other T cell subsets. Adoptive transfer of CD4+Lrig1+ T cells alleviates autoimmune symptoms in colitis and lupus nephritis mouse models. A monoclonal anti-Lrig1 antibody significantly improves the symptoms of experimental autoimmune encephalomyelitis. In conclusion, Lrig1 is an important regulator of suppressive T cell function and an exploitable target for treating autoimmune conditions.

Potential tactics with certain gut microbiota for the treatment of unresectable hepatocellular carcinoma

Hepatocellular carcinoma (HCC) constitutes an extremely malignant form of primary liver cancer. Intricate connections linking to the immune system might be associated with the pathogenesis of HCC. Meanwhile, immunotherapy with immune checkpoint inhibitors has been established to be a favorable therapeutic possibility for advanced HCC. Although curative opportunities for advanced HCC are restricted, the immune checkpoint immunotherapy has developed as the main choice for treating HCC. However, patients with metabolic-associated fatty liver disease (MAFLD)-linked HCC might be less likely to benefit from the immunotherapy alone. The limitation of the effect of the immunotherapy might be owing to the impaired T cell activation in MAFLD patients, which could be well explained by a dysfunctional gut-liver axis. Gut microbiota and their metabolites including several bile acids could contribute to modulating the responses of the immune checkpoint immunotherapy. Roles of gut microbiota in the development of cancers have expected great interest in the latest studies. Here, an interplay between the gut and liver has been presented, which might suggest to affect the efficacy of immune checkpoint immunotherapy against HCC.

Factors impacting the benefits and pathogenicity of Th17 cells in the tumor microenvironment

Tumor development is closely associated with a complex tumor microenvironment, which is composed of tumor cells, blood vessels, tumor stromal cells, infiltrating immune cells, and associated effector molecules. T helper type 17 (Th17) cells, which are a subset of CD4+ T cells and are renowned for their ability to combat bacterial and fungal infections and mediate inflammatory responses, exhibit context-dependent effector functions. Within the tumor microenvironment, different molecular signals regulate the proliferation, differentiation, metabolic reprogramming, and phenotypic conversion of Th17 cells. Consequently, Th17 cells exert dual effects on tumor progression and can promote or inhibit tumor growth. This review aimed to investigate the impact of various alterations in the tumor microenvironment on the antitumor and protumor effects of Th17 cells to provide valuable clues for the exploration of additional tumor immunotherapy strategies.

Non-coding RNA in tumor-infiltrating regulatory T cells formation and associated immunotherapy

Cancer immunotherapy has exhibited promising antitumor effects in various tumors. Infiltrated regulatory T cells (Tregs) in the tumor microenvironment (TME) restrict protective immune surveillance, impede effective antitumor immune responses, and contribute to the formation of an immunosuppressive microenvironment. Selective depletion or functional attenuation of tumor-infiltrating Tregs, while eliciting effective T-cell responses, represents a potential approach for anti-tumor immunity. Furthermore, it does not disrupt the Treg-dependent immune homeostasis in healthy organs and does not induce autoimmunity. Yet, the shared cell surface molecules and signaling pathways between Tregs and multiple immune cell types pose challenges in this process. Noncoding RNAs (ncRNAs), including microRNAs (miRNAs) and long noncoding RNAs (lncRNAs), regulate both cancer and immune cells and thus can potentially improve antitumor responses. Here, we review recent advances in research of tumor-infiltrating Tregs, with a focus on the functional roles of immune checkpoint and inhibitory Tregs receptors and the regulatory mechanisms of ncRNAs in Treg plasticity and functionality.

The CCR6/CCL20 axis expands RORγt+ Tregs to protect from glomerulonephritis

Previous studies have identified a unique Treg population, which expresses the Th17 characteristic transcription factor RORγt. These RORγt+ Tregs possess enhanced immunosuppressive capacity, which endows them with great therapeutic potential. However, as a caveat, they are also capable of secreting pro-inflammatory IL-17A. Since the sum function of RORγt+ Tregs in glomerulonephritis (GN) remains unknown, we studied the effects of their absence. Purified CD4+ T cell populations, containing or lacking RORγt+ Tregs, were transferred into immunocompromised RAG1 knockout mice and the nephrotoxic nephritis model of GN was induced. Absence of RORγt+ Tregs significantly aggravated kidney injury, demonstrating overall kidney-protective properties. Analyses of immune responses showed that RORγt+ Tregs were broadly immunosuppressive with no preference for a particular type of T cell response. Further characterization revealed a distinct functional and transcriptional profile, including enhanced production of IL-10. Expression of the chemokine receptor CCR6 marked a particularly potent subset, whose absence significantly worsened GN. As an underlying mechanism, we found that chemokine CCL20 acting through receptor CCR6 signaling mediated expansion and activation of RORγt+ Tregs. Finally, we also detected an increase of CCR6+ Tregs in kidney biopsies, as well as enhanced secretion of chemokine CCL20 in 21 patients with anti-neutrophil cytoplasmic antibody associated GN compared to that of 31 healthy living donors, indicating clinical relevance. Thus, our data characterize RORγt+ Tregs as anti-inflammatory mediators of GN and identify them as promising target for Treg directed therapies.

Regulatory mucosa-associated invariant T cells controlled by β1 adrenergic receptor signaling contribute to hepatocellular carcinoma progression

BACKGROUND AND AIMS

The innate-like mucosa-associated invariant T (MAIT) cells are enriched in human liver and have been linked to human HCC. However, their contributions to the progression of HCC are controversial due to the heterogeneity of MAIT cells, and new MAIT cell subsets remain to be explored.

APPROACH AND RESULTS

Combining single cell RNA sequencing (scRNA-seq) and flow cytometry analysis, we performed phenotypic and functional studies and found that FOXP3 + CXCR3 + MAIT cells in HCC patients were regulatory MAIT cells (MAITregs) with high immunosuppressive potential. These MAITregs were induced under Treg-inducing condition and predominantly from FOXP3 - CXCR3 + MAIT cells, which displayed mild Treg-related features and represented a pre-MAITreg reservoir. In addition, the induction and function of MAITregs were promoted by β1 adrenergic receptor signaling in pre-MAITregs and MAITregs, respectively. In HCC patients, high proportion of the intratumoral MAITregs inhibited antitumor immune responses and was associated with poor clinical outcomes.

CONCLUSIONS

Together, we reveal an immunosuppressive subset of MAIT cells in HCC patients that contributes to HCC progression, and propose a control through neuroimmune crosstalk.

The protective and pathogenic role of Th17 cell plasticity and function in the tumor microenvironment

At the turn of the century, researchers discovered a unique subtype of T helper cells that secretes IL-17 and defined it as Th17. The latest study found that Th17 cells play both positive and negative definitive roles in the regulation of antitumor immune responses. Although the function of Th17 in the tumor microenvironment remains poorly understood, more and more studies have shown that this paradoxical dual role is closely related to the plasticity of Th17 cells in recent decades. Further understanding of the characteristics of Th17 cells in the tumor microenvironment could yield novel and useful therapeutic approaches to treat cancer. In this review, we further present the high plasticity of Th17 cells and the function of Th17-producing IL-17 in tumor immunity.

Integrins in cancer: Emerging mechanisms and therapeutic opportunities

Integrins are vital surface adhesion receptors that mediate the interactions between the extracellular matrix (ECM) and cells and are essential for cell migration and the maintenance of tissue homeostasis. Aberrant integrin activation promotes initial tumor formation, growth, and metastasis. Recently, many lines of evidence have indicated that integrins are highly expressed in numerous cancer types and have documented many functions of integrins in tumorigenesis. Thus, integrins have emerged as attractive targets for the development of cancer therapeutics. In this review, we discuss the underlying molecular mechanisms by which integrins contribute to most of the hallmarks of cancer. We focus on recent progress on integrin regulators, binding proteins, and downstream effectors. We highlight the role of integrins in the regulation of tumor metastasis, immune evasion, metabolic reprogramming, and other hallmarks of cancer. In addition, integrin-targeted immunotherapy and other integrin inhibitors that have been used in preclinical and clinical studies are summarized.

Immunometabolic reprogramming, another cancer hallmark

Molecular carcinogenesis is a multistep process that involves acquired abnormalities in key biological processes. The complexity of cancer pathogenesis is best illustrated in the six hallmarks of the cancer: (1) the development of self-sufficient growth signals, (2) the emergence of clones that are resistant to apoptosis, (3) resistance to the antigrowth signals, (4) neo-angiogenesis, (5) the invasion of normal tissue or spread to the distant organs, and (6) limitless replicative potential. It also appears that non-resolving inflammation leads to the dysregulation of immune cell metabolism and subsequent cancer progression. The present article delineates immunometabolic reprogramming as a critical hallmark of cancer by linking chronic inflammation and immunosuppression to cancer growth and metastasis. We propose that targeting tumor immunometabolic reprogramming will lead to the design of novel immunotherapeutic approaches to cancer.

TH17 cell immune adaptation

At mucosal barriers, the T helper 17 (T_H17) cell population plays a fundamental role in controlling tissue homeostasis. The adaptability of this population to a more pro-inflammatory or anti-inflammatory function - that is, their functional plasticity and consequently heterogeneity - primarily depends on the environment. We would like to term this process environmental immune adaptation. Interfering with T_H17 cell adaptation leads to pathological consequences, including development of immune-mediated inflammatory diseases or even cancer. Several molecular mechanisms have been shown to participate in this process and recently, a better understanding of the transcriptional and metabolic profiling of T_H17 cells has shed light on a new level of complexity. Here, we offer a summary on the role of T_H17 cell plasticity in inflammatory diseases and cancer as well as the latest discoveries and controversies regarding the mechanisms that control the adaptability of the T_H17 cell population.

The Interleukine-17 Cytokine Family: Role in Development and Progression of Spondyloarthritis, Current and Potential Therapeutic Inhibitors

Spondyloarthritis (SpA) encompasses a group of chronic inflammatory rheumatic diseases with a predilection for the spinal and sacroiliac joints, which include axial spondyloarthritis, psoriatic arthritis, reactive arthritis, arthritis associated with chronic inflammatory bowel disease, and undifferentiated spondyloarthritis. The prevalence of SpA in the population varies from 0.5 to 2%, most commonly affecting young people. Spondyloarthritis pathogenesis is related to the hyperproduction of proinflammatory cytokines (TNFα, IL-17A, IL-23, etc.). IL-17A plays a key role in the pathogenesis of spondyloarthritis (inflammation maintenance, syndesmophites formation and radiographic progression, enthesites and anterior uveitis development, etc.). Targeted anti-IL17 therapies have established themselves as the most efficient therapies in SpA treatment. The present review summarizes literature data on the role of the IL-17 family in the pathogenesis of SpA and analyzes existing therapeutic strategies for IL-17 suppression with monoclonal antibodies and Janus kinase inhibitors. We also consider alternative targeted strategies, such as the use of other small-molecule inhibitors, therapeutic nucleic acids, or affibodies. We discuss advantages and pitfalls of these approaches and the future prospects of each method.

Batf stabilizes Th17 cell development via impaired Stat5 recruitment of Ets1-Runx1 complexes

Although the activator protein-1 (AP-1) factor Batf is required for Th17 cell development, its mechanisms of action to underpin the Th17 program are incompletely understood. Here, we find that Batf ensures Th17 cell identity in part by restricting alternative gene programs through its actions to restrain IL-2 expression and IL-2-induced Stat5 activation. This, in turn, limits Stat5-dependent recruitment of Ets1-Runx1 factors to Th1- and Treg-cell-specific gene loci. Thus, in addition to pioneering regulatory elements in Th17-specific loci, Batf acts indirectly to inhibit the assembly of a Stat5-Ets1-Runx1 complex that enhances the transcription of Th1- and Treg-cell-specific genes. These findings unveil an important role for Stat5-Ets1-Runx1 interactions in transcriptional networks that define alternate T cell fates and indicate that Batf plays an indispensable role in both inducing and maintaining the Th17 program through its actions to regulate the competing actions of Stat5-assembled enhanceosomes that promote Th1- and Treg-cell developmental programs.

Low Gut Microbial Diversity Augments Estrogen-Driven Pulmonary Fibrosis in Female-Predominant Interstitial Lung Disease

Although profibrotic cytokines, such as IL-17A and TGF-β1, have been implicated in the pathogenesis of interstitial lung disease (ILD), the interactions between gut dysbiosis, gonadotrophic hormones and molecular mediators of profibrotic cytokine expression, such as the phosphorylation of STAT3, have not been defined. Here, through chromatin immunoprecipitation sequencing (ChIP-seq) analysis of primary human CD4+ T cells, we show that regions within the STAT3 locus are significantly enriched for binding by the transcription factor estrogen receptor alpha (ERa). Using the murine model of bleomycin-induced pulmonary fibrosis, we found significantly increased regulatory T cells compared to Th17 cells in the female lung. The genetic absence of ESR1 or ovariectomy in mice significantly increased pSTAT3 and IL-17A expression in pulmonary CD4+ T cells, which was reduced after the repletion of female hormones. Remarkably, there was no significant reduction in lung fibrosis under either condition, suggesting that factors outside of ovarian hormones also contribute. An assessment of lung fibrosis among menstruating females in different rearing environments revealed that environments favoring gut dysbiosis augment fibrosis. Furthermore, hormone repletion following ovariectomy further augmented lung fibrosis, suggesting pathologic interactions between gonadal hormones and gut microbiota in relation to lung fibrosis severity. An analysis of female sarcoidosis patients revealed a significant reduction in pSTAT3 and IL-17A levels and a concomitant increase in TGF-β1 levels in CD4+ T cells compared to male sarcoidosis patients. These studies reveal that estrogen is profibrotic in females and that gut dysbiosis in menstruating females augments lung fibrosis severity, supporting a critical interaction between gonadal hormones and gut flora in lung fibrosis pathogenesis.

Low Gut Microbial Diversity Augments Estrogen-driven Pulmonary Fibrosis in Female-Predominant Interstitial Lung Disease

Although profibrotic cytokines such as IL-17A and TGF-β1 have been implicated in interstitial lung disease (ILD) pathogenesis, interactions between gut dysbiosis, gonadotrophic hormones and molecular mediators of profibrotic cytokine expression, such as phosphorylation of STAT3, have not been defined. Here we show by chromatin immunoprecipitation sequencing (ChIP-seq) analysis of primary human CD4+ T cells that regions within the STAT3 locus are significantly enriched for binding by the transcription factor estrogen receptor alpha (ERa). Using the murine model of bleomycin-induced pulmonary fibrosis, we found significantly increased regulatory T cells compared to Th17 cells in the female lung. Genetic absence of ESR1 or ovariectomy in mice significantly increased pSTAT3 and IL-17A expression in pulmonary CD4+ T cells, which was reduced after repletion of female hormones. Remarkably, there was no significant reduction in lung fibrosis under either condition, suggesting that factors outside of ovarian hormones also contribute. Assessment of lung fibrosis among menstruating females in different rearing environments revealed that environments favoring gut dysbiosis augment fibrosis. Furthermore, hormone repletion following ovariectomy further augmented lung fibrosis, suggesting pathologic interactions between gonadal hormones and gut microbiota on lung fibrosis severity. Analysis in female sarcoidosis patients revealed a significant reduction in pSTAT3 and IL-17A levels and a concomitant increase in TGF-β1 levels in CD4+ T cells, compared to male sarcoidosis patients. These studies reveal that estrogen is profibrotic in females and that gut dysbiosis in menstruating females augments lung fibrosis severity, supporting a critical interaction between gonadal hormones and gut flora in lung fibrosis pathogenesis.

Human FOXP3 and tumour microenvironment

The tumour microenvironment (TME) is a complex system composed of cancer cells, stromal cells and immune cells. Regulatory T cells (Tregs) in the TME impede immune surveillance of tumours and suppress antitumor immune responses. Transcription factor forkhead box protein 3 (FOXP3) is the main marker of Tregs, which dominates the function of Tregs. FOXP3 was originally thought to be a Tregs-specific expression molecule, and recent studies have found that FOXP3 is expressed in a variety of tumours with inconsistent functional roles. This review summarizes the recent progress of infiltrating Treg-FOXP3 and tumour-FOXP3 in TME, discusses the communication mechanism between FOXP3⁺ cells and effector T cells in TME, the relationship between FOXP3 and clinical prognosis, and the potential of FOXP3-targeted therapy.

Interleukin-23 receptor defines T helper 1-like regulatory T cells in oral squamous cell carcinoma

BACKGROUND

The immune responses play significant roles in the onset, progression, and outcome of oral squamous cell carcinoma (OSCC). CD4⁺ regulatory T cells (Tregs) significantly impact tumor immunity. However, their role in OSCC development remains elusive.

METHODS

In a carcinogen-induced mouse OSCC model, interleukin-23 receptor (IL-23R) expression on Tregs and Treg function were determined by flow cytometry. IL-23R overexpression in Tregs was achieved by lentiviral infection, followed by evaluation of the expression of Forkhead box P3 (Foxp3), T-bet, retineic-acid-receptor-related orphan nuclear receptor gamma t, and cytokines by flow cytometry. Adoptive transfer assays were applied to analyze the function of IL-23R^- overexpressing Tregs in vivo. The cellular sources of IL-23 were also determined by flow cytometry.

RESULTS

IL-23R^- Tregs and IL-23R⁺ Tregs were found in the tongues but not spleens of OSCC-bearing mice. IL-23R⁺ Tregs expressed lower Foxp3 but higher T-bet than IL-23R^- Tregs. IL-23R^- Tregs produced abundant IL-10 and transforming growth factor (TGF)-β, while IL-23R⁺ Tregs produced lower IL-10 and TGF-β but remarkably higher interferon (IFN)-γ. Furthermore, IL-23R⁺ Tregs possessed more phosphorylated signal transducer and activator of transcription (STAT3) and STAT4 than IL-23R^- Tregs. IL-23R⁺ Tregs were less immunosuppressive than IL-23R^- Tregs, as evidenced by weaker inhibition of activated conventional T cells. IL-23R overexpression in splenic Tregs remarkably reduced the expression of IL-10 and TGF-β but increased IFN-γ expression when Tregs were adoptively transferred into OSCC-bearing mice. In the OSCC microenvironment, macrophages, dendritic cells, and malignant OSCC cells produced IL-23 which might modulate the function of IL-23R⁺ Tregs.

CONCLUSIONS

This study unveils Treg heterogeneity, thus deepening the understanding of Treg biology and tumor immunity in OSCC.

FOXP3+ regulatory T cells and the immune escape in solid tumours

FOXP3+ regulatory T (Treg) cells play critical roles in establishing the immunosuppressive tumour microenvironment, which is achieved and dynamically maintained with the contribution of various stromal and immune cell subsets. However, the dynamics of non-lymphoid FOXP3+ Treg cells and the mutual regulation of Treg cells and other cell types in solid tumour microenvironment remains largely unclear. In this review, we summarize the latest findings on the dynamic connections and reciprocal regulations of non-lymphoid Treg cell subsets in accordance with well-established and new emerging hallmarks of cancer, especially on the immune escape of tumour cells in solid tumours. Our comprehension of the interplay between FOXP3+ Treg cells and key hallmarks of cancer may provide new insights into the development of next-generation engineered T cell-based immune treatments for solid tumours.

Transcriptome profile and clinical characterization of ICOS expression in gliomas

Inducible co-stimulator (ICOS), an immune costimulatory molecule, has been found to play an essential role across various malignancies. This study investigated the transcriptome profile and clinical characterization of ICOS in gliomas. Clinical information and transcriptome data of 301 glioma samples were downloaded from the Chinese Glioma Genome Atlas (CGGA) dataset for analysis (CGGA301 cohort). Furthermore, the results were validated in 697 samples with RNAseq data from the TCGA glioma dataset and 325 gliomas with RNAseq data from the CGGA325 dataset. Immunohistochemistry was performed to evaluate ICOS protein expression across different WHO grades in a tissue microarray (TMA). In addition, single-cell sequencing data from CGGA and GSE 163108 datasets were used to analyze the ICOS expression across different cell types. Statistical analyses and figure production were performed with R-language. We found that ICOS was significantly upregulated in higher-grade, IDH wild type, and mesenchymal subtype of gliomas. Functional enrichment analyses revealed that ICOS was mainly involved in glioma-related immune response. Moreover, ICOS showed a robust correlation with other immune checkpoints, including the PD1/PD-L1/PD-L2 pathway, CTLA4, ICOSL (ICOS ligand), and IDO1. Subsequent Tumor Immune Dysfunction and Exclusion (TIDE) analysis revealed that GBM patients with higher ICOS expression seemed to be more sensitive to ICB therapy. Furthermore, based on seven clusters of metagenes, GSVA identified that ICOS was tightly associated with HCK, LCK, MHC-I, MHC-II, STAT1, and interferon, especially with LCK, suggesting a strong correlation between ICOS and T-cell activity in gliomas. In cell lineage analysis, Higher-ICOS gliomas tended to recruit dendritic cells, monocytes, and macrophages into the tumor microenvironment. Single-cell sequencing analysis indicated that ICOS was highly expressed by regulatory T cells (Tregs), especially in mature Tregs. Finally, patients with higher ICOS had shortened survival. ICOS was an independent prognosticator for glioma patients. In conclusion, higher ICOS is correlated with more malignancy of gliomas and is significantly associated with Treg activity among glioma-related immune responses. Moreover, ICOS could contribute as an independent prognostic factor for gliomas. Our study highlights the role of ICOS in glioma and may facilitate therapeutic strategies targeting ICOS for glioma.

Human chorionic gonadotropin promotes murine Treg cells and restricts pregnancy-harmful proinflammatory Th17 responses

An equilibrium between proinflammatory and anti-inflammatory immune responses is essential for maternal tolerance of the fetus throughout gestation. To study the participation of fetal tissue-derived factors in this delicate immune balance, we analyzed the effects of human chorionic gonadotropin (hCG) on murine Treg cells and Th17 cells in vitro, and on pregnancy outcomes, fetal and placental growth, blood flow velocities and remodeling of the uterine vascular bed in vivo. Compared with untreated CD4⁺CD25⁺ T cells, hCG increased the frequency of Treg cells upon activation of the LH/CG receptor. hCG, with the involvement of IL-2, also interfered with induced differentiation of CD4⁺ T cells into proinflammatory Th17 cells. In already differentiated Th17 cells, hCG induced an anti-inflammatory profile. Transfer of proinflammatory Th17 cells into healthy pregnant mice promoted fetal rejection, impaired fetal growth and resulted in insufficient remodeling of uterine spiral arteries, and abnormal flow velocities. Our works show that proinflammatory Th17 cells have a negative influence on pregnancy that can be partly avoided by in vitro re-programming of proinflammatory Th17 cells with hCG.

Vitamin D, Th17 Lymphocytes, and Breast Cancer

Simple Summary

The effect of vitamin D₃ on the development of breast cancer (favorable, ineffective, or even unfavorable) depends on many factors, such as age, menopausal status, or obesity. The immunomodulatory effect of vitamin D may be unfavorable in case of breast cancer progression. The effect of vitamin D on Th17 cells may depend on disease type and patients’ age. Our goal was to summarize the data available and to find indications of vitamin D treatment failure or success. Therefore, in this review, we present data describing the effects of vitamin D₃ on Th17 cells, mainly in breast cancer.

Abstract

Vitamin D₃, which is well known to maintain calcium homeostasis, plays an important role in various cellular processes. It regulates the proliferation and differentiation of several normal cells, including immune and neoplastic cells, influences the cell cycle, and stimulates cell maturation and apoptosis through a mechanism dependent on the vitamin D receptor. The involvement of vitamin D₃ in breast cancer development has been observed in numerous clinical studies. However, not all studies support the protective effect of vitamin D₃ against the development of this condition. Furthermore, animal studies have revealed that calcitriol or its analogs may stimulate tumor growth or metastasis in some breast cancer models. It has been postulated that the effect of vitamin D₃ on T helper (Th) 17 lymphocytes is one of the mechanisms promoting metastasis in these murine models. Herein we present a literature review on the existing data according to the interplay between vitamin D, Th17 cell and breast cancer. We also discuss the effects of this vitamin on Th17 lymphocytes in various disease entities known to date, due to the scarcity of scientific data on Th17 lymphocytes and breast cancer. The presented data indicate that the effect of vitamin D₃ on breast cancer development depends on many factors, such as age, menopausal status, or obesity. According to that, more extensive clinical trials and studies are needed to assess the importance of vitamin D in breast cancer, especially when no correlations seem to be obvious.

Inflammation, Immune Senescence, and Dysregulated Immune Regulation in the Elderly

An optimal immune response requires the appropriate interaction between the innate and the adaptive arms of the immune system as well as a proper balance of activation and regulation. After decades of life, the aging immune system is continuously exposed to immune stressors and inflammatory assaults that lead to immune senescence. In this review, we will discuss inflammaging in the elderly, specifically concentrating on IL-6 and IL-1b in the context of T lymphocytes, and how inflammation is related to mortality and morbidities, specifically cardiovascular disease and cancer. Although a number of studies suggests that the anti-inflammatory cytokine TGF-b is elevated in the elderly, heightened inflammation persists. Thus, the regulation of the immune response and the ability to return the immune system to homeostasis is also important. Therefore, we will discuss cellular alterations in aging, concentrating on senescent T cells and CD4+ CD25+ FOXP3+ regulatory T cells (Tregs) in aging

Colorectal Cancer-Infiltrating Regulatory T Cells: Functional Heterogeneity, Metabolic Adaptation, and Therapeutic Targeting

Colorectal cancer (CRC) is a heterogeneous disease with one of the highest rates of incidence and mortality among cancers worldwide. Understanding the CRC tumor microenvironment (TME) is essential to improve diagnosis and treatment. Within the CRC TME, tumor-infiltrating lymphocytes (TILs) consist of a heterogeneous mixture of adaptive immune cells composed of mainly anti-tumor effector T cells (CD4+ and CD8+ subpopulations), and suppressive regulatory CD4+ T (Treg) cells. The balance between these two populations is critical in anti-tumor immunity. In general, while tumor antigen-specific T cell responses are observed, tumor clearance frequently does not occur. Treg cells are considered to play an important role in tumor immune escape by hampering effective anti-tumor immune responses. Therefore, CRC-tumors with increased numbers of Treg cells have been associated with promoting tumor development, immunotherapy failure, and a poorer prognosis. Enrichment of Treg cells in CRC can have multiple causes including their differentiation, recruitment, and preferential transcriptional and metabolic adaptation to the TME. Targeting tumor-associated Treg cell may be an effective addition to current immunotherapy approaches. Strategies for depleting Treg cells, such as low-dose cyclophosphamide treatment, or targeting one or more checkpoint receptors such as CTLA-4 with PD-1 with monoclonal antibodies, have been explored. These have resulted in activation of anti-tumor immune responses in CRC-patients. Overall, it seems likely that CRC-associated Treg cells play an important role in determining the success of such therapeutic approaches. Here, we review our understanding of the role of Treg cells in CRC, the possible mechanisms that support their homeostasis in the tumor microenvironment, and current approaches for manipulating Treg cells function in cancer.

Different subpopulations of regulatory T cells in human autoimmune disease, transplantation, and tumor immunity

CD4⁺CD25⁺ regulatory T cells (Tregs), a subpopulation of naturally CD4⁺ T cells that characteristically express transcription factor Forkhead box P3 (FOXP3), play a pivotal role in the maintenance of immune homeostasis and the prevention of autoimmunity. With the development of biological technology, the understanding of plasticity and stability of Tregs has been further developed. Recent studies have suggested that human Tregs are functionally and phenotypically diverse. The functions and mechanisms of different phenotypes of Tregs in different disease settings, such as tumor microenvironment, autoimmune diseases, and transplantation, have gradually become hot spots of immunology research that arouse extensive attention. Among the complex functions, CD4⁺CD25⁺FOXP3⁺ Tregs possess a potent immunosuppressive capacity and can produce various cytokines, such as IL‐2, IL‐10, and TGF‐β, to regulate immune homeostasis. They can alleviate the progression of diseases by resisting inflammatory immune responses, whereas promoting the poor prognosis of diseases by helping cells evade immune surveillance or suppressing effector T cells activity. Therefore, methods for targeting Tregs to regulate their functions in the immune microenvironment, such as depleting them to strengthen tumor immunity or expanding them to treat immunological diseases, need to be developed. Here, we discuss that different subpopulations of Tregs are essential for the development of immunotherapeutic strategies involving Tregs in human diseases.

Cancer Stem Cells: An Ever-Hiding Foe

Cancer stem cells are a population of cells enable to reproduce the original phenotype of the tumor and capable to self-renewal, which is crucial for tumor proliferation, differentiation, recurrence, and metastasis, as well as chemoresistance. Therefore, the cancer stem cells (CSCs) have become one of the main targets for anticancer therapy and many ongoing clinical trials test anti-CSCs efficacy of plenty of drugs. This chapter describes CSCs starting from general description of this cell population, through CSCs markers, signaling pathways, genetic and epigenetic regulation, role of epithelial-mesenchymal transition (EMT) transition and autophagy, cooperation with microenvironment (CSCs niche), and finally role of CSCs in escaping host immunosurveillance against cancer.

Stem-like intestinal Th17 cells give rise to pathogenic effector T cells during autoimmunity

While intestinal Th17 cells are critical for maintaining tissue homeostasis, recent studies have implicated their roles in the development of extra-intestinal autoimmune diseases including multiple sclerosis. However, the mechanisms by which tissue Th17 cells mediate these dichotomous functions remain unknown. Here, we characterized the heterogeneity, plasticity, and migratory phenotypes of tissue Th17 cells in vivo by combined fate mapping with profiling of the transcriptomes and TCR clonotypes of over 84,000 Th17 cells at homeostasis and during CNS autoimmune inflammation. Inter- and intra-organ single-cell analyses revealed a homeostatic, stem-like TCF1+ IL-17+ SLAMF6+ population that traffics to the intestine where it is maintained by the microbiota, providing a ready reservoir for the IL-23-driven generation of encephalitogenic GM-CSF+ IFN-γ+ CXCR6+ T cells. Our study defines a direct in vivo relationship between IL-17+ non-pathogenic and GM-CSF+ and IFN-γ+ pathogenic Th17 populations and provides a mechanism by which homeostatic intestinal Th17 cells direct extra-intestinal autoimmune disease.

The Pathogenic Roles of IL-22 in Colitis: Its Transcription Regulation by Musculin in T Helper Subsets and Innate Lymphoid Cells

IL-22 plays a crucial role in promoting inflammation, antimicrobial immunity and tissue repair at barrier surfaces. The role of IL-22 in colitis is still controversial: while IL-22 has a protective effect on gut epithelium in acute injuries, it also enhances colitis in a context-dependent manner. Here, we summarize the Yin and Yang of IL-22 in colitis. Particularly, we emphasize the role of innate lymphoid cells (ILCs) in IL-22 production and regulation. A previously underappreciated transcription factor, Musculin (MSC), has been recently identified to be expressed in not only Th17 cells, but also RORγt+/Id2+ IL-22-producing group 3 ILCs in the gut of naïve mice. We hypothesize that the co-expression and interaction of MSC with the key transcription repressor Id2 in developing lymphoid cells (e.g., in LTi cells) and ILC precursors might fine tune the developmental programs or regulate the plasticity of adaptive Th subset and innate ILCs. The much-elevated expression of IL-22 in MSC-/- ILC3s suggests that MSC may function as: 1) a transcription suppressor for cytokines, particularly for IL-22, and/or 2) a gatekeeper for specific lineages of Th cells and innate ILCs as well. Amelioration of colitis symptoms in MSC-/- mice by IL-22-blocking agent IL-22BP-Fc suggests a counterintuitive pathogenic role of IL-22 in the absence of MSC as a checkpoint. The theory that exuberant production of IL-22 under pathological conditions (e.g., in human inflammatory bowel disease, IBD) may cause epithelial inflammation due to endoplasmic reticulum (ER) stress response is worth further investigation. Rheostatic regulation of IL-22 may be of therapeutic value to restore homeostatic balance and promote intestinal health in human colitis.

Adoptive cell therapy with tumor-specific Th9 cells induces viral mimicry to eliminate antigen-loss-variant tumor cells

Resistance can occur in patients receiving adoptive cell therapy (ACT) due to antigen-loss-variant (ALV) cancer cell outgrowth. Here we demonstrate that murine and human T helper (Th) 9 cells, but not Th1/Tc1 or Th17 cells, expressing tumor-specific T cell receptors (TCRs) or chimeric antigen receptors (CARs), eradicate advanced tumors that contain ALVs. This unprecedented antitumor capacity of Th9 cells is attributed to both enhanced direct tumor cell killing and bystander antitumor effects promoted by intratumor release of interferon (IFN) α/β. Mechanistically, tumor-specific Th9 cells increase the intratumor accumulation of extracellular ATP (eATP; released from dying tumor cells), because of a unique feature of Th9 cells that lack the expression of ATP degrading ectoenzyme cluster of differentiation (CD) 39. Intratumor enrichment of eATP promotes the monocyte infiltration and stimulates their production of IFNα/β by inducing eATP-endogenous retrovirus-Toll-like receptor 3 (TLR3)/mitochondrial antiviral signaling (MAVS) pathway activation. These results identify tumor-specific Th9 cells as a unique T cell subset endowed with the unprecedented capacity to eliminate ALVs for curative responses.

Rationalizing heptadecaphobia: TH 17 cells and associated cytokines in cancer and metastasis

Cancer is one of the leading causes of death worldwide. When cancer patients are diagnosed with metastasis, meaning that the primary tumor has spread to at least one different site, their life expectancy decreases dramatically. In the past decade, the immune system´s role in fighting cancer and metastasis has been studied extensively. Importantly, immune cells and inflammatory reactions generate potent antitumor responses but also contribute to tumor development. However, the molecular and cellular mechanisms underlying this dichotomic interaction between the immune system and cancer are still poorly understood. Recently, a spotlight has been cast on the distinct subsets of immune cells and their derived cytokines since evidence has implicated their crucial impact on cancer development. T helper 17 cell (TH 17) cells, which express the master transcriptional factor Retinoic acid-receptor-related orphan receptor gamma t, are among these critical cell subsets and are defined by their production of type 3 cytokines, such as IL-17A, IL-17F, and IL-22. Depending on the tumor microenvironment, these cytokines can also be produced by other immune cell sources, such as T cytotoxic 17 cell, innate lymphoid cells, NKT cells, or γδ T cells. To date, a lot of data have been collected describing the divergent functions of IL-17A, IL-17F, and IL-22 in malignancies. In this comprehensive review, we discuss the role of these TH 17- and non-TH 17-derived type 3 cytokines in different tumor entities. Furthermore, we will provide a structured insight into the strict regulation and subsequent downstream mechanisms of these cytokines in cancer and metastasis.

Interaction between intestinal microbiota and tumour immunity in the tumour microenvironment

In recent years, an increasing number of studies have reported that intestinal microbiota have an important effect on tumour immunity by affecting the tumour microenvironment (TME). The intestinal microbiota are closely associated with various immune cells, such as T lymphocytes, natural killer cells (NK cells) and macrophages. Some bacteria, such as Akkermansia muciniphila (A. muciniphila) and Lactobacillus reuteri (L. reuteri), have been shown to improve the effect of tumour immunity. Furthermore, microbial imbalance, such as the increased abundance of Fusobacterium nucleatum (F. nucleatum) and Helicobacter hepaticus (H. hepaticus), generally causes tumour formation and progression. In addition, some microbiota also play important roles in tumour immunotherapy, especially PD-L1-related therapies. Therefore, what is the relationship between these processes and how do they affect each other? In this review, we summarize the interactions and corresponding mechanisms among the intestinal microbiota, immune system and TME to facilitate the research and development of new targeted drugs and provide new approaches to tumour therapy.

Relationship between Th17 immune response and cancer

Cancer is the second leading cause of death worldwide and epidemiological projections predict growing cancer mortality rates in the next decades. Cancer has a close relationship with the immune system and, although Th17 cells are known to play roles in the immune response against microorganisms and in autoimmunity, studies have emphasized their roles in cancer pathogenesis. The Th17 immune response profile is involved in several types of cancer including urogenital, respiratory, gastrointestinal, and skin cancers. This type of immune response exerts pro and antitumor functions through several mechanisms, depending on the context of each tumor, including the protumor angiogenesis and exhaustion of T cells and the antitumor recruitment of T cells and neutrophils to the tumor microenvironment. Among other factors, the paradoxical behavior of Th17 cells in this setting has been attributed to its plasticity potential, which makes possible their conversion into other types of T cells such as Th17/Treg and Th17/Th1 cells. Interleukin (IL)-17 stands out among Th17-related cytokines since it modulates pathways and interacts with other cell profiles in the tumor microenvironment, which allow Th17 cells to prevail in tumors. Moreover, the IL-17 is able to mediate pro and antitumor processes that influence the development and progression of various cancers, being associated with variable clinical outcomes. The understanding of the relationship between the Th17 immune response and cancer as well as the singularities of carcinogenic processes in each type of tumor is crucial for the identification of new therapeutic targets.

Functional Th1-oriented T follicular helper cells that infiltrate human breast cancer promote effective adaptive immunity

We previously demonstrated that tumor-infiltrating lymphocytes (TIL) in human breast cancer sometimes form organized tertiary lymphoid structures (TLS) characterized by CXCL13-producing T follicular helper (Tfh) cells. The present study found that CD4+ Tfh TIL, CD8+ TIL, and TIL-B, colocalizing in TLS, all express the CXCL13 receptor CXCR5. An ex vivo functional assay determined that only activated, functional Th1-oriented Tfh TIL (PD-1hiICOSint phenotype) provide help for immunoglobulin and IFN-γ production. A functional Tfh TIL presence signals an active TLS, characterized by humoral (immunoglobulins, Ki-67+ TIL-B in active germinal centers) and cytotoxic (GZMB+CD8+ and GZMB+CD68+ TIL plus Th1 gene expression) immune responses. Analysis of active versus inactive TLS in untreated patients revealed that the former are associated with positive clinical outcomes. TLS also contain functional T follicular regulatory (Tfr) TIL, which are characterized by a CD25+CXCR5+GARP+FOXP3+ phenotype and a demethylated FOXP3 gene. Functional Tfr inhibited functional Tfh activities via a glycoprotein A repetitions predominant (GARP)-associated TGF-β-dependent mechanism. The activity of tumor-associated TLS was dictated by the relative balance between functional Tfh TIL and functional Tfr TIL. These data provide mechanistic insight into TLS processes orchestrated by functional Th1-oriented Tfh TIL, including TIL-B and CD8+ TIL activation and immunological memory generation. Tfh TIL, regulated by functional Tfr TIL, are an expected key target of PD-1/PD-L1 blockade.

IRF4 is Correlated with the Conversion to a Th17-Like Phenotype in Regulatory T Cells from the Malignant Pleural Effusion

Background

RORγt⁺Foxp3⁺ (Th17-like) Tregs are a plastic Treg subset implicated in immune-related diseases; however, the mechanism of Treg phenotypic transformation in malignant pleural effusion (MPE) has not been elucidated.

Methods

The percentage of CD4⁺CD25⁺Foxp3⁺Helios⁺ and RORγt⁺Foxp3⁺ Tregs from peripheral blood and pleural effusion mononuclear cells were measured. The level of interferon regulatory factor 4 (IRF4) mRNA expression was detected by quantitative real-time reverse transcription polymerase chain reaction. The effects of IRF4 on the induction of Tregs from patients with non-small cell lung cancer (NSCLC) were evaluated in vitro. Correlation assays between IRF4 expression and the frequency of RORγt⁺Foxp3⁺ Tregs were performed.

Results

The frequency of CD4⁺CD25⁺Foxp3⁺Helios⁺ Tregs and CD4⁺RORγt⁺ Th17 cells was both increased in the MPE of NSCLC patients. The group of double-positive Foxp3⁺RORγt⁺ Treg phenotype were identified in the pleural effusion. A significant increase in the frequency of Foxp3⁺RORγt⁺ Tregs was found in MPE compared with the non-malignant pleural effusion (NPE). Compared to NPE, the relative level of IRF4 expression was increased in the MPE. IRF4 expression was positively associated with the frequency of Foxp3⁺RORγt⁺ Tregs in the PE. In vitro, the level of Helios mRNA and protein expression was reduced in induced Tregs following IRF4 over-expression. Additionally, the level of RORγt protein expression was substantially increased. However, ectopic Helios expression in induced Tregs reversed the effects induced by enhanced IRF4 expression.

Conclusion

IRF4 may serve as a potential molecule that promotes the conversion of regulatory T cells from MPE to a Th17-like phenotype by modulating Helios.

Prognostic and therapeutic TILs of cervical cancer-Current advances and future perspectives

Cervical cancer is a top lethal cancer for women worldwide. Although screening and vaccination programs are available in many countries, resulting in the decline of new cases, this is not true for developing countries where there are many new cases and related deaths. Cancer immunotherapy through adaptive cell therapy (ACT) has been applied in clinics, but now much attention is focused on autogenic tumor-infiltrating lymphocyte (TIL)-based therapy, which has shown more specificity and better ability to inhibit tumor growth. Data from melanoma and cervical cancers confirm that tumor-specific T cells in TILs can be expanded for more specific and effective ACT. Moreover, TILs are derived from individual patients and are ready to home back to kill tumor cells after patient infusion, aligning well with personalized and precision medicine. In addition to therapy, TIL cell types and numbers are good indicators of host immune response to the tumor, and thus they have significant values in prognosis. Because of the special relationship with human papillomavirus (HPV) infection, cervical cancer has some specialties in TIL-based prognosis and therapy. In this review, we summarize the recent advances in the prognostic significance of TILs and TIL-based therapy for cervical cancer and discuss related perspectives.

The cross talk between gastric cancer stem cells and the immune microenvironment: a tumor-promoting factor

Cross talk between cancer cells and the immune system is determinant for cancer progression. Emerging evidence demonstrates that GC characteristics such as metastasis, treatment resistance, and disease recurrence are associated with a tumor subpopulation called gastric cancer stem cells (GCSCs). However, the specific interaction between GCSCs and the immune microenvironment is still under investigation. Although immune evasion has been well described for cancer stem cells (CSCs), recent studies show that GCSCs can also regulate the immune system and even benefit from it. This review will provide an overview of bidirectional interactions between CSCs and immune cells in GC, compiling relevant data about how CSCs can induce leukocyte reprogramming, resulting in pro-tumoral immune cells that orchestrate promotion of metastasis, chemoresistance, tumorigenicity, and even increase in number of cancer cells with stem properties. Some immune cells studied are tumor-associated macrophages (TAMs), neutrophils, Th17 and T regulatory (T_reg) cells, mesenchymal stem cells (MSCs), and cancer-associated fibroblasts (CAFs), as well as the signaling pathways involved in these pro-tumoral activities. Conversely, although there are cytotoxic leukocytes that can potentially eliminate GCSCs, we describe mechanisms for immune evasion in GCSCs and their clinical implications. Furthermore, we describe current available immunotherapy targeting GCSC-related markers as possible treatment for GC, discussing how the CSC-modified immune microenvironment can mitigate or inactivate these immunotherapies, limiting their effectiveness. Finally, we summarize key concepts and relevant evidence to understand the cross talk between GCSCs and the immune microenvironment as an important process for effective design of therapies against GCSCs that improve the outcome of patients with GC.

Oleanolic acid regulates the Treg/Th17 imbalance in gastric cancer by targeting IL-6 with miR-98-5p

BACKGROUND

Gastric cancer (GC) was a type of malignant tumor with a very high fatality rate. Oleanolic acid (OA) was a class of pentacyclic triterpenes which was proved to have anti-cancer activity. While the specific molecular mechanism of OA's role in inhibiting GC was not fully understood. This study aimed to explore how OA played an anti-cancer role in GC.

METHODS

Expression of miR-98-5p was examined using qPCR, and expression levels of Treg/Th17-related factors were evaluated using qPCR and western blot. Flow cytometry was conducted to assess the proportion of Treg cells and Th17 cells. Besides, dual luciferase reporter assay was performed to verify that IL-6 was a target of miR-98-5p.

RESULTS

Downregulation of miR-98-5p and upregulation of Treg/Th17-related factors were observed in GC tissues. What's more, the Treg/Th17 imbalance was found in PBMCs of GC patients. Overexpression of miR-98-5p promoted balance of Treg/Th17 cells via directly targeting IL-6 to downregulate expression of IL-6. Finally, OA could promote balance of Treg/Th17 cells by upregulating expression of miR-98-5p.

DISCUSSION

All our results proved that OA could promote balance of Treg/Th17 cells in GC by targeting IL-6 with miR-98-5p, indicating a potential drug for treatment of GC.

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.