Targeting TNFR2 in Cancer: All Roads Lead to Rome

Microwave ablation of non-small cell lung cancer enhances local T-cell abundance and alters monocyte interactions

BACKGROUND

Minimally invasive thermal therapies show great prospect in non-small cell lung cancer (NSCLC) treatment. However, changes in immune cell populations following microwave ablation (MWA) in NSCLC microenvironment are not fully revealed.

OBJECTIVE

The present study was conducted to identify changes in immune cell populations and analyse dysregulated genes in immune cells after MWA in NSCLC microenvironment.

METHODS

The patients received fractionated MWA in two treatments separated by 3 weeks. Tumor biopsy samples were obtained through core-needle biopsy before each fractionated MWA procedure at the same site and used for single-cell RNA sequencing with the 10x Genomics pipeline.

RESULTS

A total of 9 major cell types were identified after MWA, which include neutrophils, T cells, B cells, monocytes, epithelial cells, chondrocytes, macrophages, tissue stem cells, and endothelial cells. After MWA, the tumor tissue exhibited an increased proportion of T cells. MWA altered gene expression in each cell cluster at the single-cell level. Cell trajectory analysis revealed that the cells at the starting point were most like T helper cells, naïve T cells, and regulatory T cells; they then developed into anergic T cells, T follicular cells, natural killer T cells, T memory cells, and exhausted T cells, and finally ended as γδ T cells and cytotoxic T cells. Moreover, after MWA, more interaction between monocytes and T cells (or B cells) were identified.

CONCLUSIONS

MWA increases local T-cell abundance and alters monocyte interactions, thereby reshaping the tumor microenvironment. This study lays a foundation for investigating dysregulated genes that may contribute to the MWA-induced immune response in NSCLC.

WHAT IS ALREADY KNOWN ON THIS TOPIC

Thermal ablation may change the immune profiles of patients by activating various steps in the cancer immunity cycle. However, changes in immune cell populations following MWA of NSCLC have not been fully reported.

WHAT THIS STUDY ADDS

After MWA, an increase in interactions between monocytes and T cells intratumorally was observed, which promoted antitumor immunity.

HOW THIS STUDY MIGHT AFFECT RESEARCH, PRACTICE OR POLICY

The current study illuminates the MWA-caused systemic immune response in NSCLC, which may help to identify the dysregulated genes involved in the MWA-caused immune response.

The implications of the TNFα-TNFR2 immune checkpoint signaling pathway in cancer treatment: From immunoregulation to angiogenesis

Despite the tremendous advances that have been made in biomedical research, cancer remains one of the leading causes of death worldwide. Several therapeutic approaches have been suggested and applied to treat cancer with impressive results. Immunotherapy based on targeting immune checkpoint signaling pathways proved to be one of the most efficient. In this review article, we will focus on the recently discovered TNFα-TNFR2 signaling pathway, which controls the immunological and pro-angiogenic properties of many immunoregulatory and pro-angiogenic cells such as endothelial progenitor cells (EPCs), mesenchymal stem cells (MSCs), and regulatory T cells (Tregs). Due to their biological properties, these cells can play a major role in cancer progression and metastasis. Therefore, we will discuss the advantages and disadvantages of an anti-TNFR2 treatment that could carry two faces under one hood. It interrupts the immunosuppressive and pro-angiogenic behaviors of the above-mentioned cells and interferes with tumor growth and survival.

Targeting the TNF and TNFR superfamilies in autoimmune disease and cancer

The first anti-tumour necrosis factor (TNF) monoclonal antibody, infliximab (Remicade), celebrated its 25th anniversary of FDA approval in 2023. Inhibitors of TNF have since proved clinically efficacious at reducing inflammation associated with several autoimmune diseases, including rheumatoid arthritis, psoriasis and Crohn's disease. The success of TNF inhibitors raised unrealistic expectations for targeting other members of the TNF superfamily (TNFSF) of ligands and their receptors, with difficulties in part related to their more limited, variable expression and potential redundancy. However, there has been a resurgence of interest and investment, with many of these cytokines or their cognate receptors now under clinical investigation as targets for modulation of autoimmune and inflammatory diseases, as well as cancer. This Review assesses TNFSF-targeted biologics currently in clinical development for immune system-related diseases, highlighting ongoing challenges and future directions.

Association between tumor necrosis factor receptor 2 and progression and poor prognosis of tumor stage 2‑3 esophageal squamous cell carcinoma and stratified analysis

Although tumor necrosis factor receptor 2 (TNFR2) may serve a protumor role in several types of tumors, the clinical significance of TNFR2, including the diagnostic and prognostic value in tumor (T) stage 2-3 esophageal squamous cell carcinoma (ESCC), remains unclear. Therefore, the present study aimed to explore the clinical significance of TNFR2 in stage T2-3 ESCC. The present study collected the mRNA expression data of TNFR2 from two databases and confirmed the high expression of TNFR2 in ESCC tissue. TNFR2 expression in stage T2-3 ESCC tissue (n=404) was detected using immunohistochemistry and a stratified analysis was performed. For all patients with stage T2-3 ESCC, TNFR2 expression was associated with clinical stage, invasion depth and metastatic lymph nodes. Stage T3 and low differentiation was associated with an increase in the risk of lymph node metastasis, but older age was associated with a decrease. TNFR2 expression was associated with poor overall survival (OS) of all patients with stage T2-3 ESCC and stratified patients with stage T3 ESCC. Moreover, TNFR2 expression and metastatic lymph nodes were independent prognostic factors for these patients. For stratified patients aged ≤60 years, TNFR2 expression was associated with clinical stage and metastatic lymph nodes. In addition, TNFR2 expression was associated with poor OS in stratified patients with stage T2 ESCC. The presence of metastatic lymph nodes was also an independent prognostic factor for these patients. For stratified patients aged >60 years, TNFR2 expression was associated with invasion depth. TNFR2 expression was also associated with poor OS in all patients with stage T2-3 ESCC and stratified patients with stage T3 ESCC. TNFR2 expression and metastatic lymph nodes were identified as independent prognostic factors for these patients. In conclusion, TNFR2 expression is associated with progression and poor prognosis in patients with stage T2-3 ESCC as an independent prognostic factor, except in the subgroup of patients with stage T2-3 ESCC aged ≤60 years.

Targeting TNFR2 for cancer immunotherapy: recent advances and future directions

Cancer is the leading cause of death worldwide, accounting for nearly 10 million deaths every year. Immune checkpoint blockade approaches have changed the therapeutic landscape for many tumor types. However, current immune checkpoint inhibitors PD-1 or CTLA-4 are far from satisfactory, due to high immune-related adverse event incident (up to 60%) and the inefficiency in cases of "cold" tumor microenvironment. TNFR2, a novel hopeful tumor immune target, was initially proposed in 2017. It not only promotes tumor cell proliferation, but also correlates with the suppressive function of Treg cells, implicating in the development of an immunosuppressive tumor microenvironment. In preclinical studies, TNFR2 antibody therapy has demonstrated efficacy alone or a potential synergistic effect when combined with classical PD-1/ CTLA-4 antibodies. The focus of this review is on the characteristics, functions, and recent advancements in TNFR2 therapy, providing a new direction for the next generation of anti-tumor alternative therapy.

Development of pharmacological immunoregulatory anti-cancer therapeutics: current mechanistic studies and clinical opportunities

Immunotherapy represented by anti-PD-(L)1 and anti-CTLA-4 inhibitors has revolutionized cancer treatment, but challenges related to resistance and toxicity still remain. Due to the advancement of immuno-oncology, an increasing number of novel immunoregulatory targets and mechanisms are being revealed, with relevant therapies promising to improve clinical immunotherapy in the foreseeable future. Therefore, comprehending the larger picture is important. In this review, we analyze and summarize the current landscape of preclinical and translational mechanistic research, drug development, and clinical trials that brought about next-generation pharmacological immunoregulatory anti-cancer agents and drug candidates beyond classical immune checkpoint inhibitors. Along with further clarification of cancer immunobiology and advances in antibody engineering, agents targeting additional inhibitory immune checkpoints, including LAG-3, TIM-3, TIGIT, CD47, and B7 family members are becoming an important part of cancer immunotherapy research and discovery, as are structurally and functionally optimized novel anti-PD-(L)1 and anti-CTLA-4 agents and agonists of co-stimulatory molecules of T cells. Exemplified by bispecific T cell engagers, newly emerging bi-specific and multi-specific antibodies targeting immunoregulatory molecules can provide considerable clinical benefits. Next-generation agents also include immune epigenetic drugs and cytokine-based therapeutics. Cell therapies, cancer vaccines, and oncolytic viruses are not covered in this review. This comprehensive review might aid in further development and the fastest possible clinical adoption of effective immuno-oncology modalities for the benefit of patients.

Role of T cells in liver metastasis

The liver is a major metastatic site (organ) for gastrointestinal cancers (such as colorectal, gastric, and pancreatic cancers) as well as non-gastrointestinal cancers (such as lung, breast, and melanoma cancers). Due to the innate anatomical position of the liver, the apoptosis of T cells in the liver, the unique metabolic regulation of hepatocytes and other potential mechanisms, the liver tends to form an immunosuppressive microenvironment and subsequently form a pre-metastatic niche (PMN), which can promote metastasis and colonization by various tumor cells(TCs). As a result, the critical role of immunoresponse in liver based metastasis has become increasingly appreciated. T cells, a centrally important member of adaptive immune response, play a significant role in liver based metastases and clarifying the different roles of the various T cells subsets is important to guide future clinical treatment. In this review, we first introduce the predisposing factors and related mechanisms of liver metastasis (LM) before introducing the PMN and its transition to LM. Finally, we detail the role of different subsets of T cells in LM and advances in the management of LM in order to identify potential therapeutic targets for patients with LM.

Continuous TNF-α exposure in mammary epithelial cells promotes cancer phenotype acquisition via EGFR/TNFR2 activation

Tumor necrosis factor alpha (TNF-α), an abundant inflammatory cytokine in the tumor microenvironment (TME), is linked to breast cancer growth and metastasis. In this study, we established MCF10A cell lines incubated with TNF-α to investigate the effects of continuous TNF-α exposure on the phenotypic change of normal mammary epithelial cells. The established MCF10A-LE cell line, through long-term exposure to TNF-α, displayed cancer-like features, including increased proliferation, migration, and sustained survival signaling even in the absence of TNF-α stimulation. Unlike the short-term exposed cell line MCF10A-SE, MCF10A-LE exhibited elevated levels of epidermal growth factor receptor (EGFR) and subsequent TNF receptor 2 (TNFR2), and silencing of EGFR or TNFR2 suppressed the cancer-like phenotype of MCF10A-LE. Notably, we demonstrated that the elevated levels of NAD(P)H oxidase 4 (NOX4) and the resulting increase in reactive oxygen species (ROS) were associated with EGFR/TNFR2 elevation in MCF10A-LE. Furthermore, mammosphere-forming capacity and the expression of cancer stem cell (CSC) markers increased in MCF10A-LE. Silencing of EGFR reversed these effects, indicating the acquisition of CSC-like properties via EGFR signaling. In conclusion, our results reveal that continuous TNF-α exposure activates the EGFR/TNFR2 signaling pathway via the NOX4/ROS axis, promoting neoplastic changes in mammary epithelial cells within the inflammatory TME.

Development of a 1:1-binding biparatopic anti-TNFR2 antagonist by reducing signaling activity through epitope selection

Conventional bivalent antibodies against cell surface receptors often initiate unwanted signal transduction by crosslinking two antigen molecules. Biparatopic antibodies (BpAbs) bind to two different epitopes on the same antigen, thus altering crosslinking ability. In this study, we develop BpAbs against tumor necrosis factor receptor 2 (TNFR2), which is an attractive immune checkpoint target. Using different pairs of antibody variable regions specific to topographically distinct TNFR2 epitopes, we successfully regulate the size of BpAb-TNFR2 immunocomplexes to result in controlled agonistic activities. Our series of results indicate that the relative positions of the two epitopes recognized by the BpAb are critical for controlling its signaling activity. One particular antagonist, Bp109-92, binds TNFR2 in a 1:1 manner without unwanted signal transduction, and its structural basis is determined using cryo-electron microscopy. This antagonist suppresses the proliferation of regulatory T cells expressing TNFR2. Therefore, the BpAb format would be useful in designing specific and distinct antibody functions.

Exploring the crosstalk between endothelial cells, immune cells, and immune checkpoints in the tumor microenvironment: new insights and therapeutic implications

The tumor microenvironment (TME) is a highly intricate milieu, comprising a multitude of components, including immune cells and stromal cells, that exert a profound influence on tumor initiation and progression. Within the TME, angiogenesis is predominantly orchestrated by endothelial cells (ECs), which foster the proliferation and metastasis of malignant cells. The interplay between tumor and immune cells with ECs is complex and can either bolster or hinder the immune system. Thus, a comprehensive understanding of the intricate crosstalk between ECs and immune cells is essential to advance the development of immunotherapeutic interventions. Despite recent progress, the underlying molecular mechanisms that govern the interplay between ECs and immune cells remain elusive. Nevertheless, the immunomodulatory function of ECs has emerged as a pivotal determinant of the immune response. In light of this, the study of the relationship between ECs and immune checkpoints has garnered considerable attention in the field of immunotherapy. By targeting specific molecular pathways and signaling molecules associated with ECs in the TME, novel immunotherapeutic strategies may be devised to enhance the efficacy of current treatments. In this vein, we sought to elucidate the relationship between ECs, immune cells, and immune checkpoints in the TME, with the ultimate goal of identifying novel therapeutic targets and charting new avenues for immunotherapy.

Therapeutic potential of TNFR2 agonists: a mechanistic perspective

TNFR2 agonists have been investigated as potential therapies for inflammatory diseases due to their ability to activate and expand immunosuppressive CD4+Foxp3+ Treg cells and myeloid-derived suppressor cells (MDSCs). Despite TNFR2 being predominantly expressed in Treg cells at high levels, activated effector T cells also exhibit a certain degree of TNFR2 expression. Consequently, the role of TNFR2 signaling in coordinating immune or inflammatory responses under different pathological conditions is complex. In this review article, we analyze possible factors that may determine the therapeutic outcomes of TNFR2 agonism, including the levels of TNFR2 expression on different cell types, the biological properties of TNFR2 agonists, and disease status. Based on recent progress in the understanding of TNFR2 biology and the study of TNFR2 agonistic agents, we discuss the future direction of developing TNFR2 agonists as a therapeutic agents.

Role of tumor necrosis factor-alpha in the central nervous system: a focus on autoimmune disorders

Tumor necrosis factor-alpha (TNF-α) is a pleiotropic immune cytokine that belongs to the TNF superfamily of receptor ligands. The cytokine exists as either a transmembrane or a soluble molecule, and targets two distinct receptors, TNF-α receptor 1 (TNFR1) and TNF-α receptor 2 (TNFR2), which activate different signaling cascades and downstream genes. TNF-α cellular responses depend on its molecular form, targeted receptor, and concentration levels. TNF-α plays a multifaceted role in normal physiology that is highly relevant to human health and disease. In the central nervous system (CNS), this cytokine regulates homeostatic functions, such as neurogenesis, myelination, blood-brain barrier permeability and synaptic plasticity. However, it can also potentiate neuronal excitotoxicity and CNS inflammation. The pleiotropism of TNF-α and its various roles in the CNS, whether homeostatic or deleterious, only emphasizes the functional complexity of this cytokine. Anti-TNF-α therapy has demonstrated effectiveness in treating various autoimmune inflammatory diseases and has emerged as a significant treatment option for CNS autoimmune diseases. Nevertheless, it is crucial to recognize that the effects of this therapeutic target are diverse and complex. Contrary to initial expectations, anti-TNF-α therapy has been found to have detrimental effects in multiple sclerosis. This article focuses on describing the various roles, both physiological and pathological, of TNF-α in the CNS. Additionally, it discusses the specific disease processes that are dependent or regulated by TNF-α and the rationale of its use as a therapeutic target.

Neutrophil-intrinsic TNF receptor signaling orchestrates host defense against Staphylococcus aureus

Staphylococcus aureus is the leading cause of skin and soft tissue infections and is a major health burden due to the emergence of antibiotic-resistant strains. To address the unmet need of alternative treatments to antibiotics, a better understanding of the protective immune mechanisms against S. aureus skin infection is warranted. Here, we report that tumor necrosis factor (TNF) promoted protection against S. aureus in the skin, which was mediated by bone marrow-derived immune cells. Furthermore, neutrophil-intrinsic TNF receptor (TNFR) signaling directed immunity against S. aureus skin infections. Mechanistically, TNFR1 promoted neutrophil recruitment to the skin, whereas TNFR2 prevented systemic bacterial dissemination and directed neutrophil antimicrobial functions. Treatment with a TNFR2 agonist showed therapeutic efficacy against S. aureus and Pseudomonas aeruginosa skin infections, which involved increased neutrophil extracellular trap formation. Our findings revealed nonredundant roles for TNFR1 and TNFR2 in neutrophils for immunity against S. aureus and can be therapeutically targeted for protection against bacterial skin infections.

A Multigene-Panel Study Identifies Single Nucleotide Polymorphisms Associated with Prostate Cancer Risk

The immune system plays a critical role in modulating cancer development and progression. Polymorphisms in key genes involved in immune responses are known to affect susceptibility to cancer. Here, we analyzed 35 genes to evaluate the association between variants of genes involved in immune responses and prostate cancer risk. Thirty-five genes were analyzed in 47 patients with prostate cancer and 43 healthy controls using next-generation sequencing. Allelic and genotype frequencies were calculated in both cohorts, and a generalized linear mixed model was applied to test the relationship between prostate cancer risk and nucleotide substitution. Odds ratios were calculated to describe the association between each single nucleotide polymorphism (SNP) and prostate cancer risk. Significant changes in allelic and genotypic distributions were observed for IL4R, IL12RB1, IL12RB2, IL6, TMPRSS2, and ACE2. Furthermore, a generalized linear mixed model identified statistically significant associations between prostate cancer risk and SNPs in IL12RB2, IL13, IL17A, IL4R, MAPT, and TFNRS1B. Finally, a statistically significant association was observed between IL2RA and TNFRSF1B and Gleason scores, and between SLC11A1, TNFRSF1B and PSA values. We identified SNPs in inflammation and two prostate cancer-associated genes. Our results provide new insights into the immunogenetic landscape of prostate cancer and the impact that SNPs on immune genes may have on affecting the susceptibility to prostate cancer.

TNFR2 expression predicts the responses to immune checkpoint inhibitor treatments

Immune checkpoint inhibitors (ICIs) by targeting PD-1/PD-L1 or CTLA-4 have markedly improved the outcome of cancer patients. However, most solid tumor patients can't benefit from such therapy. Identification of novel biomarkers to predict the responses of ICIs is crucial to enhance their therapeutic efficacy. TNFR2 is highly expressed by the maximally immunosuppressive subset of CD4⁺Foxp3⁺ regulatory T cells (Tregs), especially those present in tumor microenvironment (TME). Since Tregs represent a major cellular mechanism in tumor immune evasion, TNFR2 may be a useful biomarker to predict the responses to ICIs therapy. This notion is supported by our analysis of the computational tumor immune dysfunction and exclusion (TIDE) framework from published single-cell RNA-seq data of pan-cancer databases. The results show that, as expected, TNFR2 is highly expressed by tumor-infiltrating Tregs. Interestingly, TNFR2 is also expressed by the exhausted CD8 T cells in breast cancer (BRCA), hepatocellular carcinoma (HCC), lung squamous cell carcinoma (LUSC), and melanoma (MELA). Importantly, high expression of TNFR2 is associated with poor responses to the treatment with ICIs in BRCA, HCC, LUSC, and MELA. In conclusion, the expression of TNFR2 in TME may be a reliable biomarker for the precision of ICIs treatment of cancer patients, and this idea merits further research.

Leveraging the tolerogenic potential of TNF-α and regulatory B cells in organ transplantation

A subset of B-cells with tolerogenic functions, termed B-regulatory cells or Bregs, is characterized by the expression of anti-inflammatory/tolerogenic cytokines, namely IL-10, TGF-β, and IL-35, that contribute to their regulatory functions. Breg regulation favors graft acceptance within a tolerogenic milieu. As organ transplantation invariably triggers inflammation, new insights into the crosstalk between cytokines with dual properties and the inflamed milieu are needed to tailor their function toward tolerance. Using TNF-α as a proxy of dual-function cytokines involved in immune-related diseases and transplantation settings, the current review highlights the multifaceted role of TNF-α. It focuses on therapeutic approaches that have revealed the complexity of TNF-α properties tested in clinical settings where total TNF-α inhibition has proven ineffective and often detrimental to clinical outcomes. To improve the efficacy of current TNF-α inhibiting therapeutics, we propose a three-prong strategy to upregulate the tolerogenic pathway engaging the TNFR2 receptor while simultaneously inhibiting the inflammatory mechanisms associated with TNFR1 engagement. When combined with additional administrations of Bregs-TLR that activate Tregs, this approach may become a potential therapeutic in overcoming transplant rejection and promoting graft tolerance.

The Crosstalk between HepG2 and HMC-III Cells: In Vitro Modulation of Gene Expression with Conditioned Media

Epidemiological studies have postulated an inverse correlation between developing cancer and neurodegeneration. It is known that the secretome plays a vital role in cell-cell communication in health and disease; the microglia is the resident macrophage of the central nervous system which maintains neuronal integrity by adapting as the microenvironment changes. The present study aimed to identify, in a cell model, biomarkers that link neurodegenerative diseases to cancer or vice versa. Real-time PCR and western blot analysis were used to characterize the effects on gene and protein expression of human hepatoblastoma (HepG2) and human microglia (HMC-III) cells after exchanging part of their conditioned medium. Biomarkers of the endoplasmic reticulum, and mitophagy and inflammatory processes were evaluated. In both cell types, we observed the activation of cytoprotective mechanisms against any potential pro-oxidant or pro-inflammatory signals present in secretomes. In contrast, HepG2 but not HMC-III cells seem to trigger autophagic processes following treatment with conditioned medium of microglia, thus suggesting a cell-specific adaptive response.

Elevation of circulating TNF receptor 2 in cancer: A systematic meta-analysis for its potential as a diagnostic cancer biomarker

High Tumor Necrosis Factor Receptor 2 (TNFR2) expression is characteristic of diverse malignant cells during tumorigenesis. The protein is also expressed by many immunosuppressive cells during cancer development, allowing cancer immune escape. A growing body of evidence further suggests a correlation between the circulating form of this protein and cancer development. Here we conducted a systematic meta-analysis of cancer studies published up until 1st October 2022, in which the circulating soluble TNFR2 (sTNFR2) concentrations in patients with cancers were recorded and their association with cancer risk was assessed. Of the 14,615 identified articles, 44 studies provided data on the correlation between cancer risk and the level of circulating sTNFR2. The pooled means comparison showed a consistently significant increase in the levels of sTNFR2 in diverse cancers when compared to healthy controls. These included colorectal cancer, ovarian cancer, breast cancer, non-Hodgkin's lymphoma, Hodgkin's lymphoma, lung cancer, hepatocarcinoma, and glioblastoma. In a random-effect meta-analysis, the cancer-specific odd ratios (OR) showed significant correlations between increased circulating sTNFR2 levels and the risk of colorectal cancer, non-Hodgkin's lymphoma, and hepatocarcinoma at 1.59 (95% CI:1.20-2.11), 1.98 (95% CI:1.49-2.64) and 4.32 (95% CI:2.25-8.31) respectively. The overall result showed an association between circulating levels of sTNFR2 and the risk of developing cancer at 1.76 (95% CI:1.53-2.02). This meta-analysis supports sTNFR2 as a potential diagnostic biomarker for cancer, albeit with different predictive strengths for different cancer types. This is consistent with a potential key role for TNFR2 involvement in cancer development.

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.