Functional delineation and differentiation dynamics of human CD4+ T cells expressing the FoxP3 transcription factor

Advance in pathogenesis of sarcoidosis: Triggers and progression

Sarcoidosis, a multisystemic immune disease, significantly impacts patients' quality of life. The complexity and diversity of its pathogenesis, coupled with limited comprehensive research, had hampered both diagnosis and treatment, resulting in an unsatisfactory prognosis for many patients. In recent years, the research had made surprising progress in the triggers of sarcoidosis (genetic inheritance, infection and environmental factors) and the abnormal regulations on immunity during the formation of granuloma. This review consolidated the latest findings on sarcoidosis research, providing a systematic exploration of advanced studies on triggers, immune-related regulatory mechanisms, and clinical applications. By synthesizing previous discoveries, we aimed to offer valuable insights for future research directions and the development of clinical diagnosis and treatment strategies.

Overcoming cold tumors: a combination strategy of immune checkpoint inhibitors

Immune Checkpoint Inhibitors (ICIs) therapy has advanced significantly in treating malignant tumors, though most 'cold' tumors show no response. This resistance mainly arises from the varied immune evasion mechanisms. Hence, understanding the transformation from 'cold' to 'hot' tumors is essential in developing effective cancer treatments. Furthermore, tumor immune profiling is critical, requiring a range of diagnostic techniques and biomarkers for evaluation. The success of immunotherapy relies on T cells' ability to recognize and eliminate tumor cells. In 'cold' tumors, the absence of T cell infiltration leads to the ineffectiveness of ICI therapy. Addressing these challenges, especially the impairment in T cell activation and homing, is crucial to enhance ICI therapy's efficacy. Concurrently, strategies to convert 'cold' tumors into 'hot' ones, including boosting T cell infiltration and adoptive therapies such as T cell-recruiting bispecific antibodies and Chimeric Antigen Receptor (CAR) T cells, are under extensive exploration. Thus, identifying key factors that impact tumor T cell infiltration is vital for creating effective treatments targeting 'cold' tumors.

Single-center randomized trial of T-reg graft alone vs T-reg graft plus tacrolimus for the prevention of acute GVHD

ABSTRACT

Allogeneic hematopoietic cell transplantation (HCT) is a curative therapy for hematological malignancies for which graft-versus-host disease (GVHD) remains a major complication. The use of donor T-regulatory cells (Tregs) to prevent GVHD appears promising, including in our previous evaluation of an engineered graft product (T-reg graft) consisting of the timed, sequential infusion of CD34+ hematopoietic stem cells and high-purity Tregs followed by conventional T cells. However, whether immunosuppressive prophylaxis can be removed from this protocol remains unclear. We report the results of the first stage of an open-label single-center phase 2 study (NCT01660607) investigating T-reg graft in myeloablative HCT of HLA-matched and 9/10-matched recipients. Twenty-four patients were randomized to receive T-reg graft alone (n = 12) or T-reg graft plus single-agent GVHD prophylaxis (n = 12) to determine whether T-reg graft alone was noninferior in preventing acute GVHD. All patients developed full-donor myeloid chimerism. Patients with T-reg graft alone vs with prophylaxis had incidences of grade 3 to 4 acute GVHD of 58% vs 8% (P = .005) and grade 3 to 4 of 17% vs 0% (P = .149), respectively. The incidence of moderate-to-severe chronic GVHD was 28% in the T-reg graft alone arm vs 0% with prophylaxis (P = .056). Among patients with T-reg graft and prophylaxis, CD4+ T-cell-to-Treg ratios were reduced after transplantation, gene expression profiles showed reduced CD4+ proliferation, and the achievement of full-donor T-cell chimerism was delayed. This study indicates that T-reg graft with single-agent tacrolimus is preferred over T-reg graft alone for the prevention of acute GVHD. This trial was registered at www.clinicaltrials.gov as #NCT01660607.

Treg cells as a protective factor for Hashimoto`s thyroiditis: a Mendelian randomization study

Background and objectives

Hashimoto's thyroiditis (HT), a chronic autoimmune disorder impacting thyroid function, is a growing public health concern. The relationship between Treg cells and HT has been extensively studied, with Treg cells considered crucial in suppressing HT progression. However, these studies have mainly been observational, limiting our understanding of Treg cells' impact on HT risk. Leveraging large datasets, we utilized Mendelian randomization (MR) analysis to examine the causal association between Treg cell biomarkers and HT, providing additional validation for these relationships.

Methods

Comprehensive two-sample Mendelian randomization analysis was performed to determine the causal association between Treg cells signatures and HT in this study. Based on publicly available genetic data, we explored causal associations between 165 Treg cells signatures and HT risk.

Results

The European cohort study has identified five Treg cell phenotypes that causally protect against HT risk. Resting Treg %CD4 (OR = 0.975, 95% CI = 0.954~0.998, P = 0.030); CD4 on resting Treg (OR = 0.938, 95% CI = 0.882~0.997, P = 0.041; CD28- CD8dim %CD8dim (OR = 0.983, 95% CI = 0.969~0.998, P = 0.030); CD25 on CD39+ resting Treg (OR = 0.926, 95% CI = 0.864~0.991, P = 0.026); 5) CD28 on activated & secreting Treg (OR = 0.969, 95% CI = 0.942~0.996, P = 0.025). The Asian cohort study has identified four Treg cell phenotypes negatively correlated with the risk of HT. CD25hi %T cell (OR = 0.635, 95% CI = 0.473~852, P = 0.002); CD4 Treg %CD4 (OR = 0.829, 95% CI = 0.687~1.000, P = 0.050); CD127-CD8br %T cell (OR = 0.463, 95% CI =0.311~0.687, P< 0.001); CD3 on resting Treg (OR = 0.786, 95% CI = 0.621~0.994, P = 0.044).

Conclusion

Our study has demonstrated the close connection between Treg cells and HT by genetic means, thus providing foundational basis for future research.

Targeting tumor-infiltrating tregs for improved antitumor responses

Immunotherapies have revolutionized the landscape of cancer treatment. Regulatory T cells (Tregs), as crucial components of the tumor immune environment, has great therapeutic potential. However, nonspecific inhibition of Tregs in therapies may not lead to enhanced antitumor responses, but could also trigger autoimmune reactions in patients, resulting in intolerable treatment side effects. Hence, the precision targeting and inhibition of tumor-infiltrating Tregs is of paramount importance. In this overview, we summarize the characteristics and subpopulations of Tregs within tumor microenvironment and their inhibitory mechanisms in antitumor responses. Furthermore, we discuss the current major strategies targeting regulatory T cells, weighing their advantages and limitations, and summarize representative clinical trials targeting Tregs in cancer treatment. We believe that developing therapies that specifically target and suppress tumor-infiltrating Tregs holds great promise for advancing immune-based therapies.

Aberrant RNA sensing in regulatory T cells causes systemic autoimmunity

Chronic and aberrant nucleic acid sensing causes type I IFN-driven autoimmune diseases, designated type I interferonopathies. We found a significant reduction of regulatory T cells (Tregs) in patients with type I interferonopathies caused by mutations in ADAR1 or IFIH1 (encoding MDA5). We analyzed the underlying mechanisms using murine models and found that Treg-specific deletion of Adar1 caused peripheral Treg loss and scurfy-like lethal autoimmune disorders. Similarly, knock-in mice with Treg-specific expression of an MDA5 gain-of-function mutant caused apoptosis of peripheral Tregs and severe autoimmunity. Moreover, the impact of ADAR1 deficiency on Tregs is multifaceted, involving both MDA5 and PKR sensing. Together, our results highlight the dysregulation of Treg homeostasis by intrinsic aberrant RNA sensing as a potential determinant for type I interferonopathies.

Dynamic Responses of Circulating T Cells After Stereotactic Body Radiation Therapy for Bone Metastasis in Patients With Breast Cancer

PURPOSE

Preclinical studies have shown that radiation therapy modulates antitumor immune responses. However, circulating T-cell responses after radiation therapy in patients with cancer have been poorly characterized. This study aims to explore the changes in circulating T cells after stereotactic body radiation therapy (SBRT).

METHODS AND MATERIALS

Peripheral blood samples of 30 patients with breast cancer who underwent SBRT for bone metastasis were analyzed using multicolor flow cytometry. Phenotypes of PD-1+ CD8+ T cells and regulatory T (TREG) cells were examined. Additionally, plasma protein levels were analyzed using a bead-based immunoassay.

RESULTS

Circulating PD-1+ CD8+ T cells, which are enriched for tumor-specific clonotypes, were activated at 1 week after SBRT. However, circulating TREG cells were also activated after SBRT; this pattern was also evident among effector Foxp3hiCD45RA- TREG cells. We observed no difference in T-cell responses according to the fraction size and number. Notably, activation of TREG cells was more prominent in patients who experienced greater activation of PD-1+ CD8+ T cells. Plasma level changes in TGF-β1, soluble CTLA-4, and soluble 4-1BB at 1 week after SBRT were associated with PD-1+ CD8+ T-cell responses. Activation of TREG cells at 1 week after SBRT was associated with worse progression-free survival. Clinical factors including molecular subtype were not associated with the T-cell responses.

CONCLUSIONS

SBRT induced activation of both potentially tumor-specific CD8+ T cells and TREG cells, which were tightly associated with each other. These results may support the use of TREG cell-modulating strategies with SBRT to improve the antitumor immune response.

Tumor-infiltrating mast cells stimulate ICOS+ regulatory T cells through an IL-33 and IL-2 axis to promote gastric cancer progression

INTRODUCTION

In solid tumors, regulatory T cell (Treg) and mast cell perform different roles depending on the microenvironment. Nevertheless, mast cell and Treg-mediated interactions in gastric cancer (GC) are unclear, as are their regulation, function, and clinical significance.

OBJECTIVE

The present study demonstrated the mechanism of tumor-infiltrating mast cells stimulating ICOS+ regulatory T cells via the IL-33/IL-2 axis to promote the growth of gastric cancer.

METHODS

Analyses of 98 patients with GC were conducted to examine mast cell counts, ICOS+ Tregs, and the levels of IL-33 or IL-2. Isolated ICOS+ Treg and CD8+ T cell were stimulated, cultured and tested for their functional abilities in vitro and in vivo.

RESULTS

GC patients exhibited a significantly more production of IL-33 in tumors. Mast cell stimulated by tumor-derived IL-33 exhibited a prolonged lifespan through IL-33 mediated inhibition of apoptosis. Moreover, mast cells stimulated by tumor-derived IL-33 secreted IL-2, which induced Treg expansion. These inducible Tregs displayed an activated immunosuppressive phenotype with positive expression for the inducible T cell co-stimulator (ICOS). In vitro, IL-2 from IL to 33-stimulated mast cells induced increased numbers of ICOS+ Tregs with increased immunosuppressive activity against proliferation and effector function of CD8+ T cell. In vivo, ICOS+ Tregs were treated with anti-IL-2 neutralizing antibody followed by co-injection with CD8+ T cells in GC mouse model, which showed an increased CD8+ T cell infiltration and effector molecules production, meanwhile tumor growth and progression were inhibited. Besides, reduction in GC patient survival was associated with tumor-derived ICOS+ Tregs.

CONCLUSION

Our results highlight a crosstalk between GC-infiltrating mast cells and ICOS+ Tregs and provide a novel mechanism describing ICOS+ Treg expansion and induction by an IL-33/mast cell/IL-2 signaling axis in GC, and also provide functional evidence that the modulation of this immunosuppressive pathway can attenuate GC-mediated immune tolerance.

The Role of Regulatory T Cells in Allergic Diseases: Collegium Internationale Allergologicum (CIA) Update 2024

BACKGROUND

Allergy represents a major health problem of increasing prevalence worldwide with a high socioeconomic impact. Our knowledge on the molecular mechanisms underlying allergic diseases and their treatments has significantly improved over the last years. The generation of allergen-specific regulatory T cells (Tregs) is crucial in the induction of healthy immune responses to allergens, preventing the development and worsening of allergic diseases.

SUMMARY

In the last decades, intensive research has focused on the study of the molecular mechanisms involved in Treg development and Treg-mediated suppression. These mechanisms are essential for the induction of sustained tolerance by allergen-specific immunotherapy (AIT) after treatment discontinuation. Compelling experimental evidence demonstrated altered suppressive capacity of Tregs in patients suffering from allergic rhinitis, allergic asthma, food allergy, or atopic dermatitis, as well as the restoration of their numbers and functionality after successful AIT.

KEY MESSAGE

The better understanding of the molecular mechanisms involved in Treg generation during allergen tolerance induction might well contribute to the development of novel strategies for the prevention and treatment of allergic diseases.

Regulatory T and B cells in pediatric Henoch-Schönlein purpura: friends or foes?

BACKGROUND AND OBJECTIVES

Henoch-Schönlein purpura (HSP) is the most common immunoglobulin A-mediated systemic vasculitis in childhood. We studied immune dysregulation in HSP by analyzing regulatory T (Treg), T helper 3 (Th3), and regulatory B cell (Breg) subpopulations that might intervene in immune activation, IgA production, and HSP clinical manifestations.

METHODS

This prospective study included 3 groups of children: 30 HSP on acute phase, 30 HSP on remission, and 40 healthy controls (HCs) matched on age. Treg, Breg, and Th3 were analyzed by flow cytometry. Serum immunoglobulin and cytokine levels were quantified by ELISA and Luminex.

RESULTS

Treg frequencies were higher in acute HSP than in remitting HSP and HCs (6.53% [4.24; 9.21] vs. 4.33% [3.6; 5.66], p = 0.002, and vs. 4.45% [3.01; 6.6], p = 0.003, respectively). Activated Th3 cells (FoxP3 + Th3 cells) tend to be more abundant in HSP than in HCs (78.43% [50.62; 80.84] vs. 43.30% [40.20; 49.32], p = 0.135). Serum IgA, IL-17, and latency-associated peptide (a marker of the anti-inflammatory cytokine TGF-beta production) were significantly and inflammatory cytokines TNF-alpha, IL-1-beta, and IL-6 were non-significantly higher in HSP than HCs. Bregs were identical between the groups, but, in patients with renal impairment, Breg percentage was lower compared to those without. Treg removal in PBMC culture resulted in an increase in IgA production in HSP proving a negative regulatory role of Tregs on IgA production.

CONCLUSIONS

In pediatric HSP, immune activation persists in spite of an increase in Th3 and Tregs. Th3 could be involved in IgA hyperproduction, inefficiently downregulated by Tregs. Lack of Bregs appears linked to renal impairment.

A disrupted FOXP3 transcriptional signature underpins systemic regulatory T cell insufficiency in early pregnancy failure

Regulatory T (Treg) cell defects are implicated in disorders of embryo implantation and placental development, but the origins of Treg cell dysfunction are unknown. Here, we comprehensively analyzed the phenotypes and transcriptional profile of peripheral blood Treg cells in individuals with early pregnancy failure (EPF). Compared to fertile subjects, EPF subjects had 32% fewer total Treg cells and 54% fewer CD45RA+CCR7+ naive Treg cells among CD4+ T cells, an altered Treg cell phenotype with reduced transcription factor FOXP3 and suppressive marker CTLA4 expression, and lower Treg:Th1 and Treg:Th17 ratios. RNA sequencing demonstrated an aberrant gene expression profile, with upregulation of pro-inflammatory genes including CSF2, IL4, IL17A, IL21, and IFNG in EPF Treg cells. In silico analysis revealed 25% of the Treg cell dysregulated genes are targets of FOXP3. We conclude that EPF is associated with systemic Treg cell defects arising due to disrupted FOXP3 transcriptional control and loss of lineage fidelity.

Remote Ischemic Post-conditioning Reduces Cognitive Impairment in Rats Following Subarachnoid Hemorrhage: Possible Involvement in STAT3/STAT5 Phosphorylation and Th17/Treg Cell Homeostasis

The inflammatory response following subarachnoid hemorrhage (SAH) may lead to Early Brain Injury and subsequently contribute to poor prognosis such as cognitive impairment in patients. Currently, there is a lack of effective strategies for SAH to ameliorate inflammation and improve cognitive impairment in clinical. This study aims to examine the inhibitory impact of remote ischemic post-conditioning (RIPostC) on the body's inflammatory response by regulating Th17/Treg cell homeostasis after SAH. The ultimate goal is to search for potential early treatment targets for SAH. The rat SAH models were made by intravascular puncture of the internal carotid artery. The intervention of RIPostC was administered for three consecutive days immediately after successful modeling. Behavioral experiments including the Morris water maze and Y-maze tests were conducted to assess cognitive functions such as spatial memory, working memory, and learning abilities 2 weeks after successful modeling. The ratio of Th17 cells and Treg cells in the blood was detected using flow cytometry. Immunofluorescence was used to observe the infiltration of neutrophils into the brain. Signal transducers and activators of transcription 5 (STAT5) and signal transducers and activators of transcription 3 (STAT3) phosphorylation levels, receptor-related orphan receptor gamma-t (RORγt), and forkhead box protein P3 (Foxp3) levels were detected by Western blot. The levels of anti-inflammatory factors (IL-2, IL-10, IL-5, etc.) and pro-inflammatory factors (IL-6, IL-17, IL-18, TNF-α, IL-14, etc.) in blood were detected using Luminex Liquid Suspension Chip Assay. RIPostC significantly improved the cognitive impairment caused by SAH in rats. The results showed that infiltration of Th17 cells and neutrophils into brain tissue increased after SAH, leading to the release of pro-inflammatory factors (IL-6, IL-17, IL-18, and TNF-α). This response can be inhibited by RIPostC. Additionally, RIPostC facilitates the transfer of Treg from blood to the brain and triggers the release of anti-inflammatory (IL-2, IL-10, and IL-5) factors to suppress the inflammation following SAH. Finally, it was found that RIPostC increased the phosphorylation of STAT5 while decreasing the phosphorylation of STAT3. RIPostC reduces inflammation after SAH by partially balancing Th17/Treg cell homeostasis, which may be related to downregulation of STAT3 and upregulation of STAT5 phosphorylation, which ultimately alleviates cognitive impairment in rats. Targeting Th17/Treg cell homeostasis may be a promising strategy for early SAH treatment.

Hypothesis of a CD137/Eomes activating axis for effector T cells in HPV oropharyngeal cancers

Chronic Human Papilloma Virus (HPV) infection is supplanting alcohol and tobacco intoxications as the leading cause of oropharyngeal cancer in developed countries. HPV-related squamous cell carcinomas of the oropharynx (HPV + OSC) present better survival and respond better to radiotherapy and chemotherapy. Regulatory T cells (TREG) are mainly described as immunosuppressive and protumoral in most solid cancers. However, TREG are paradoxically associated with a better prognosis in HPV + OSCs. The transcription factor FoxP3 is the basis for the identification of TREG. Among CD4 + FoxP3 + T cells, some have effector functions. A medical hypothesis is formulated here: the existence of a CD137 (4.1BB)-Eomesodermin (Eomes) activated pathway downstream of TCR-specific activation in a subpopulation of CD4 + FoxP3 + T cells may explain this effector function. Evidence suggest that this axis may exist either in CD4 + FoxP3 + T cells or CD8 + T cells. This pathway could lead T cells to strong antitumor cytotoxic activity in a tumor-specific manner. Furthermore, CD137 is one of the most expected targets for the development of agonist immunotherapies. The identification of CD137 + Eomes + FoxP3+/- T cells could be a key element in the selective activation of the most anti-tumor cells in the HPV + OSC microenvironment.

Single-cell transcriptome landscape of circulating CD4+ T cell populations in autoimmune diseases

CD4+ T cells are key mediators of various autoimmune diseases; however, their role in disease progression remains unclear due to cellular heterogeneity. Here, we evaluated CD4+ T cell subpopulations using decomposition-based transcriptome characterization and canonical clustering strategies. This approach identified 12 independent gene programs governing whole CD4+ T cell heterogeneity, which can explain the ambiguity of canonical clustering. In addition, we performed a meta-analysis using public single-cell datasets of over 1.8 million peripheral CD4+ T cells from 953 individuals by projecting cells onto the reference and cataloging cell frequency and qualitative alterations of the populations in 20 diseases. The analyses revealed that the 12 transcriptional programs were useful in characterizing each autoimmune disease and predicting its clinical status. Moreover, genetic variants associated with autoimmune diseases showed disease-specific enrichment within the 12 gene programs. The results collectively provide a landscape of single-cell transcriptomes of CD4+ T cell subpopulations involved in autoimmune disease.

Metabolic advantages of regulatory T cells dictated by cancer cells

Cancer cells employ glycolysis for their survival and growth (the "Warburg effect"). Consequently, surrounding cells including immune cells in the tumor microenvironment (TME) are exposed to hypoglycemic, hypoxic, and low pH circumstances. Since effector T cells depend on the glycolysis for their survival and functions, the metabolically harsh TME established by cancer cells is unfavorable, resulting in the impairment of effective antitumor immune responses. By contrast, immunosuppressive cells such as regulatory T (Treg) cells can infiltrate, proliferate, survive, and exert immunosuppressive functions in the metabolically harsh TME, indicating the different metabolic dependance between effector T cells and Treg cells. Indeed, some metabolites that are harmful for effector T cells can be utilized by Treg cells; lactic acid, a harmful metabolite for effector T cells, is available for Treg cell proliferation and functions. Deficiency of amino acids such as tryptophan and glutamine in the TME impairs effector T cell activation but increases Treg cell populations. Furthermore, hypoxia upregulates fatty acid oxidation via hypoxia-inducible factor 1α (HIF-1α) and promotes Treg cell migration. Adenosine is induced by the ectonucleotidases CD39 and CD73, which are strongly induced by HIF-1α, and reportedly accelerates Treg cell development by upregulating Foxp3 expression in T cells via A2AR-mediated signals. Therefore, this review focuses on the current views of the unique metabolism of Treg cells dictated by cancer cells. In addition, potential cancer combination therapies with immunotherapy and metabolic molecularly targeted reagents that modulate Treg cells in the TME are discussed to develop "immune metabolism-based precision medicine".

Small molecule inhibitors targeting regulatory T cells for cancer treatment

Regulatory T cells (Tregs) are important controllers of the immune system homeostasis by preventing disproportionate immune responses. In the context of cancer, Tregs contribute to tumor development by suppressing other immune cells in the tumor microenvironment (TME). Infiltration of Tregs in the TME has been associated with poor prognosis in cancer patients. Thus, understanding the mechanisms underlying Treg recruitment and suppressive functions is essential for developing cancer immunotherapies to boost antitumor immune responses. While antibody-based strategies targeting Tregs have shown promise, small molecule inhibitors offer distinct advantages, including oral bioavailability and the ability to penetrate the TME and target intracellular proteins. Here, we provide an overview of small molecule inhibitors that have demonstrated efficacy in modulating Tregs activity in cancer and highlight the need for phenotypic assays to characterize therapeutic compounds.

Regulatory T-cell dysfunctions are associated with increase in tumor necrosis factor α in autoimmune hemolytic anemia and participate in Th17 polarization

Warm autoimmune hemolytic anemia (wAIHA) is a rare acquired autoimmune disease mediated by antibodies targeting red blood cells. The involvement of CD4 T-helper cells has been scarcely explored, with most findings extrapolated from animal models. Here, we performed quantification of both effector T lymphocytes (Teff) and regulatory T cells (Treg), associated with functional and transcriptomic analyses of Treg in human wAIHA. We observed a shift of Teff toward a Th17 polarization concordant with an increase in serum interleukin-17 concentration that correlates with red blood cell destruction parameters, namely lactate dehydrogenase and bilirubin levels. A decrease in circulating Treg, notably effector Treg, associated with a functional deficiency, as represented by their decrease capability to inhibit Teff proliferation, were also observed. Treg deficiency was associated with a reduced expression of Foxp3, the master transcription factor known to maintain the Treg phenotype stability and suppressive functions. Transcriptomic profiling of Treg revealed activation of the tumor necrosis facto (TNF)-α pathway, which was linked to increased serum TNF-α concentrations that were twice as high as in controls. Treg transcriptomic profiling also suggested that post-translational mechanisms possibly accounted for Foxp3 downregulation and Treg dysfunctions. Since TNF-α participates in the rupture of immune tolerance during wAIHA, its inhibition could be of interest. To this end, the effects of fostamatinib, a SYK inhibitor, were investigated in vitro, and we showed that besides the inhibition of erythrocyte phagocytosis by monocytes, fostamatinib is also able to dampen TNF-α production, thus appearing as a promising multitargeting therapy in wAIHA (clinicaltrials gov. Identifier: NCT02158195).

Tissue and circulating biomarkers of benefit to immunotherapy in extensive-stage small cell lung cancer patients

Extensive stage-Small-Cell Lung Cancer (ES-SCLC) is an aggressive cancer with dismal prognosis. The addition of immune-checkpoint inhibitors (ICIs) to platinum-based chemotherapy have been consistently demonstrated to improve outcomes and survival, becoming the new standard in first - line treatment of ES-SCLC patients. However, despite positive results reported in the pivotal trials, longer benefit appears evident only for a selected group of patients. Several predictive biomarkers have been studied so far but the prospective identification of patients more likely to experience better outcome seems to be challenging in SCLC. Indeed, classical immune predictive biomarkers as PD-L1 and tumor mutational burden (TMB) seem not to correlate with outcomes. Recently, a new molecular classification of SCLC based on differential expression of genes associated with specific clinical behaviors and therapeutic vulnerability have been presented suggesting a new field to be investigated. Despite the achievements, these studies focused mainly on inter-tumoral heterogeneity, limiting the exploration of intra-tumoral heterogeneity and cell to cell interactions. New analysis methods are ongoing in order to explore subtypes plasticity. Analysis on single biopsies cannot catch the whole genomic profile and dynamic change of disease over time and during treatment. Moreover, the availability of tissue for translational research is limited due to the low proportion of patients undergoing surgery. In this context, liquid biopsy is a promising tool to detect reliable predictive biomarkers. Here, we reviewed the current available data on predictive role of tissue and liquid biomarkers in ES-SCLC patients receiving ICIs. We assessed latest results in terms of predictive and prognostic value of gene expression profiling in SCLC. Finally, we explored the role of liquid biopsy as a tool to monitor SCLC patients over time.

Regulatory T cells in spondyloarthropathies: genetic evidence, functional role, and therapeutic possibilities

Regulatory T cells (Tregs) are a very specialized subset of T lymphocytes: their main function is controlling immune responses during inflammation. T-regs involvement in autoimmune and immune-mediated rheumatic diseases is well-described. Here, we critically review the up-to-date literature findings on the role of Tregs in spondyloarthropathies, particularly in ankylosing spondylitis (AS), a polygenic inflammatory rheumatic disease that preferentially affects the spine and the sacroiliac joints. Genetics discoveries helped in elucidating pathogenic T-regs gene modules and functional involvement. We highlight T-regs tissue specificity as crucial point, as T-regs might have a distinct epigenomic and molecular profiling depending on the different site of tissue inflammation. Furthermore, we speculate about possible therapeutic interventions targeting, or enhancing, Treg cells in spondyloarthropathies.

Beyond FOXP3: a 20-year journey unravelling human regulatory T-cell heterogeneity

The initial idea of a distinct group of T-cells responsible for suppressing immune responses was first postulated half a century ago. However, it is only in the last three decades that we have identified what we now term regulatory T-cells (Tregs), and subsequently elucidated and crystallized our understanding of them. Human Tregs have emerged as essential to immune tolerance and the prevention of autoimmune diseases and are typically contemporaneously characterized by their CD3+CD4+CD25high CD127lowFOXP3+ phenotype. It is important to note that FOXP3+ Tregs exhibit substantial diversity in their origin, phenotypic characteristics, and function. Identifying reliable markers is crucial to the accurate identification, quantification, and assessment of Tregs in health and disease, as well as the enrichment and expansion of viable cells for adoptive cell therapy. In our comprehensive review, we address the contributions of various markers identified in the last two decades since the master transcriptional factor FOXP3 was identified in establishing and enriching purity, lineage stability, tissue homing and suppressive proficiency in CD4+ Tregs. Additionally, our review delves into recent breakthroughs in innovative Treg-based therapies, underscoring the significance of distinct markers in their therapeutic utilization. Understanding Treg subsets holds the key to effectively harnessing human Tregs for immunotherapeutic approaches.

Treg in inborn errors of immunity: gaps, knowns and future perspectives

Regulatory T cells (Treg) are essential for immune balance, preventing overreactive responses and autoimmunity. Although traditionally characterized as CD4+CD25+CD127lowFoxP3hi, recent research has revealed diverse Treg subsets such as Tr1, Tr1-like, and CD8 Treg. Treg dysfunction leads to severe autoimmune diseases and immune-mediated inflammatory disorders. Inborn errors of immunity (IEI) are a group of disorders that affect correct functioning of the immune system. IEI include Tregopathies caused by genetic mutations affecting Treg development or function. In addition, Treg dysfunction is also observed in other IEIs, whose underlying mechanisms are largely unknown, thus requiring further research. This review provides a comprehensive overview and discussion of Treg in IEI focused on: A) advances and controversies in the evaluation of Treg extended subphenotypes and function; B) current knowledge and gaps in Treg disturbances in Tregopathies and other IEI including Treg subpopulation changes, genotype-phenotype correlation, Treg changes with disease activity, and available therapies, and C) the potential of Treg cell-based therapies for IEI with immune dysregulation. The aim is to improve both the diagnostic and the therapeutic approaches to IEI when there is involvement of Treg. We performed a non-systematic targeted literature review with a knowledgeable selection of current, high-quality original and review articles on Treg and IEI available since 2003 (with 58% of the articles within the last 6 years) in the PubMed database.

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.

Chimeric antigen receptor Treg therapy in transplantation

In the quest for more precise and effective organ transplantation therapies, chimeric antigen receptor (CAR) regulatory T cell (Treg) therapies represent a potential cutting-edge advance. This review comprehensively analyses CAR Tregs and how they may address important drawbacks of polyclonal Tregs and conventional immunosuppressants. We examine a growing body of preclinical findings of CAR Treg therapy in transplantation, discuss CAR Treg design specifics, and explore established and attractive new targets in transplantation. In addition, we explore present impediments where future studies will be necessary to determine the efficacy of CAR Tregs in reshaping alloimmune responses and transplant microenvironments to reduce reliance on chemical immunosuppressants. Overall, ongoing studies and trials are crucial for understanding the full scope of CAR Treg therapy in transplantation.

Blockade of CD80/CD86-CD28 co-stimulation augments the inhibitory function of peptide antigen-specific regulatory T cells

Mixed lymphocyte culture under the blockade of CD80/CD86-CD28 co-stimulation induces anergic (completely hyporesponsive) T cells with immune suppressive function (inducible suppressing T cells: iTS cells). Previously, iTS cell therapy has demonstrated outstanding benefits in clinical trials for organ transplantation. Here, we examined whether peptide antigen-specific iTS cells are inducible. DO 11.10 iTS cells were obtained from splenocytes of BALB/c DO 11.10 mice by stimulation with OVA peptide and antagonistic anti-CD80/CD86 mAbs. When DO 11.10 iTS or Foxp3- DO 11.10 iTS cells were stimulated with OVA, these cells produced IL-13, but not IL-4. DO 11.10 iTS cells decreased IL-4 and increased IL-13 production from OVA-stimulated naïve DO 11.10 splenocytes. When Foxp3+ DO 11.10 iTS cells were prepared, these cells significantly inhibited the production of IL-4 and IL-13 compared with freshly isolated Foxp3+ DO 11.10 T cells. Moreover, an increase in the population expressing OX40, ICOS, and 4-1BB suggested activation of Foxp3+ DO 11.10 iTS cells. Thus, blockade of CD80/CD86-CD28 co-stimulation during peptide antigen stimulation augments the inhibitory function of Foxp3+ regulatory T cells, and does not induce anergic Foxp3- conventional T cells. Peptide-specific Foxp3+ regulatory iTS cells could be useful for the treatment of allergic and autoimmune diseases without adverse effects.

Long-term Effects of IL-6 Receptor Blockade Therapy on Regulatory Lymphocytes and Neutrophils in Neuromyelitis Optica Spectrum Disorder

BACKGROUND AND OBJECTIVES

Neuromyelitis optica spectrum disorder (NMOSD) is a disabling autoimmune neurologic disease. Anti-IL-6 receptor (IL-6R) therapy prevents relapses in patients with anti-aquaporin 4 (AQP4)-IgG-positive NMOSD; however, it remains unclear how cellular immune components are altered by anti-IL-6R therapy. In this study, we examined the long-term effects of the anti-IL-6R monoclonal antibody tocilizumab (TCZ) on immune cell profiles in patients with NMOSD.

METHODS

Monthly IV injections of TCZ (8 mg/kg) were administered as an add-on therapy to 19 anti-AQP4-IgG-positive patients, who had been refractory to corticosteroids and immunosuppressive drugs. Peripheral blood was collected before infusion of TCZ for flow cytometry analysis of lymphocyte subsets. Seven patients provided whole blood samples for gene expression profiles.

RESULTS

Patients with NMOSD had reduced numbers of lymphocyte subsets with regulatory functions, including transitional B cells, CD56high NK cells, and CD45RA-FoxP3high regulatory T cells. However, after initiating TCZ therapy, the numbers increased to normal levels within 1 year. Gene expression analysis revealed that neutrophil granule-related genes, predominated by those related to azurophil granules, were significantly upregulated in patients with NMOSD. Such alterations suggestive of accelerated myeloid turnover were not observed 1 year after TCZ therapy, and the effects of TCZ on some neutrophil genes were observed as early as 5 days after starting TCZ. In vitro analysis demonstrated that naïve T-cell division was impaired in the enrolled patients, which was fully recovered after 18 months of therapy.

DISCUSSION

In patients with active NMOSD not treated with molecular targeting drugs, we observed reduction or deficiency in lymphocytes with regulatory potentials and activation of neutrophils. However, introduction of anti-IL-6R therapy accompanied by tapering concomitant drugs corrected such abnormalities, which might contribute to persistent relapse prevention. The recovery in the naïve T-cell division after starting TCZ may underlie the relatively low risk of infection in patients under anti-IL-6R therapy.

TRIAL REGISTRATION INFORMATION

University Hospital Medical Information Network Clinical Trials Registry: UMIN000005889 (July 8, 2011) and UMIN000007866 (May 1, 2012) (umin.ac.jp/ctr/index.htm). The first participant was enrolled on November 2, 2011.

What happens to regulatory T cells in multiple myeloma

Abnormal tumor microenvironment and immune escape in multiple myeloma (MM) are associated with regulatory T cells (Tregs), which play an important role in maintaining self-tolerance and regulating the overall immune response to infection or tumor cells. In patients with MM, there are abnormalities in the number, function and distribution of Tregs, and these abnormalities may be related to the disease stage, risk grade and prognosis of patients. During the treatment, Tregs have different responses to various treatment regiments, thus affecting the therapeutic effect of MM. It is also possible to predict the therapeutic response by observing the changes of Tregs. In addition to the above, we reviewed the application of Tregs in the treatment of MM. In conclusion, there is still much room for research on the mechanism and application of Tregs in MM.

Transcriptome profiling of regulatory T cells from children with transient hypogammaglobulinemia of infancy

Transient hypogammaglobulinemia of infancy (THI) is one of the most common forms of hypogammaglobulinemia in the early childhood. THI is usually associated with chronic, recurrent bacterial and viral infections, life-threatening in some cases, yet its pathogenesis is still largely unknown. As our previous findings indicated the possible role of Treg cells in the pathomechanism of THI, the aim of the current study was to investigate gene expression profile of Treg cells isolated from THI patients. The transcriptome-wide gene profiling was performed using microarray technology on THI patients in two time-points: during (THI-1), and in resolution phase (THI-2) of hypogammaglobulinemia. As a result, a total of 1086 genes were differentially expressed in THI-1 patients, when compared to THI-2 as well as control group. Among them, 931 were up- and 155 downregulated, and part of them encodes genes important for Treg lymphocyte biology and function, i.e. transcription factors/cofactors that regulate FOXP3 expression. Thus, we postulate that Treg cells isolated from THI patients during hypogammaglobulinemia display enhanced suppressor transcriptome signature. Treg expression profile of THI children after normalization of Ig levels largely resembles the results obtained in healthy control group, suggesting THI Treg transcriptome seems to return to that observed in healthy children. Taken together, we suggest that THI pathomechanism is associated not only with transiently elevated Treg cell numbers, but also with their enhanced regulatory/inhibitory functions. These findings expand our knowledge of human Treg cells and may be useful for the future diagnosis or management of THI.

Diversity of intratumoral regulatory T cells in B-cell non-Hodgkin lymphoma

Tumor-infiltrating regulatory T cells (Tregs) contribute to an immunosuppressive tumor microenvironment. Despite extensive studies, the prognostic impact of tumor-infiltrating Tregs in B-cell non-Hodgkin lymphomas (B-NHLs) remains unclear. Emerging studies suggest substantial heterogeneity in the phenotypes and suppressive capacities of Tregs, emphasizing the importance of understanding Treg diversity and the need for additional markers to identify highly suppressive Tregs. Here, we applied single-cell RNA sequencing and T-cell receptor sequencing combined with high-dimensional cytometry to decipher the heterogeneity of intratumoral Tregs in diffuse large B-cell lymphoma and follicular lymphoma (FL), compared with that in nonmalignant tonsillar tissue. We identified 3 distinct transcriptional states of Tregs: resting, activated, and unconventional LAG3+FOXP3- Tregs. Activated Tregs were enriched in B-NHL tumors, coexpressed several checkpoint receptors, and had stronger immunosuppressive activity compared with resting Tregs. In FL, activated Tregs were found in closer proximity to CD4+ and CD8+ T cells than other cell types. Furthermore, we used a computational approach to develop unique gene signature matrices, which were used to enumerate each Treg subset in cohorts with bulk gene expression data. In 2 independent FL cohorts, activated Tregs was the major subset, and high abundance was associated with adverse outcome. This study demonstrates that Tregs infiltrating B-NHL tumors are transcriptionally and functionally diverse. Highly immunosuppressive activated Tregs were enriched in tumor tissue but absent in the peripheral blood. Our data suggest that a deeper understanding of Treg heterogeneity in B-NHL could open new paths for rational drug design, facilitating selective targeting to improve antitumor immunity.

Allogeneic NK cells induce monocyte-to-dendritic cell conversion, control tumor growth, and trigger a pro-inflammatory shift in patient-derived cultures of primary and metastatic colorectal cancer

INTRODUCTION

Natural killer (NK) cells are innate lymphocytes with a key role in the defense against tumors. Recently, allogeneic NK cell-based therapies have gained interest because of their ability to directly lyse tumor cells without inducing graft-versus-host disease. As NK cells are also able to influence the function of other immune cells (most notably dendritic cells (DC)), a better understanding of the effects of allogeneic NK cell products on the host immune system is required. In this study, we analyzed the effects of an allogeneic off-the-shelf NK cell product, on the tumor microenvironment (TME) of primary and metastatic colorectal cancer (pCRC and mCRC, respectively). Moreover, we explored if the combination of NK cells with R848, a toll-like receptors 7/8 ligand, could further enhance any pro-inflammatory effects.

METHODS

Ex vivo expanded umbilical cord blood stem cell derived NK cells were co-cultured with pCRC or mCRC single-cell suspensions in the presence or absence of R848 for 5 days, during and after which flow cytometry and cytokine release profiling were performed.

RESULTS

NK cells efficiently induced lysis of tumor cells in both pCRC and mCRC single-cell suspensions and thereby controlled growth rates during culture. They also induced differentiation of infiltrating monocytic cells to an activated DC phenotype. Importantly, this NK-mediated myeloid conversion was also apparent in cultures after tumor cell depletion and was further enhanced by combining NK cells with R848. Moreover, NK cells, and to a greater extent, the combination of NK cells and R848, triggered CD8+ and CD4+ T-cell activation as well as a reduction in activated regulatory T cell rates. Finally, the combination of NK cells and R848 induced a pro-inflammatory shift in the cytokine release profile resulting in higher levels of interferon (IFN)-γ, interleukin (IL)-2, IL-12p70, and IFN-α as well as a reduction in IL-6, in both pCRC and mCRC cultures.

CONCLUSION

Allogeneic NK cells engaged in favorable myeloid crosstalk, displayed effective antitumor activity and, when combined with R848, induced a pro-inflammatory shift of the CRC TME. These findings prompt the investigation of NK cells and R848 as a combination therapy for solid tumors.

First-in-human therapy with Treg produced from thymic tissue (thyTreg) in a heart transplant infant

Due to their suppressive capacity, regulatory T cells (Tregs) have attracted growing interest as an adoptive cellular therapy for the prevention of allograft rejection, but limited Treg recovery and lower quality of adult-derived Tregs could represent an obstacle to success. To address this challenge, we developed a new approach that provides large quantities of Tregs with high purity and excellent features, sourced from thymic tissue routinely removed during pediatric cardiac surgeries (thyTregs). We report on a 2-year follow-up of the first patient treated worldwide with thyTregs, included in a phase I/II clinical trial evaluating the administration of autologous thyTreg in infants undergoing heart transplantation. In addition to observing no adverse effects that could be attributed to thyTreg administration, we report that the Treg frequency in the periphery was preserved during the 2-year follow-up period. These initial results are consistent with the trial objective, which is to confirm safety of the autologous thyTreg administration and its capacity to restore the Treg pool.

Hematopoietic cell-based and non-hematopoietic cell-based strategies for immune tolerance induction in living-donor renal transplantation: A systematic review

INTRODUCTION

Despite its use to prevent acute rejection, lifelong immunosuppression can adversely impact long-term patient and graft outcomes. In theory, immunosuppression withdrawal is the ultimate goal of kidney transplantation, and is made possible by the induction of immunological tolerance. The purpose of this paper is to review the safety and efficacy of immune tolerance induction strategies in living-donor kidney transplantation, both chimerism-based and non-chimerism-based. The impact of these strategies on transplant outcomes, including acute rejection, allograft function and survival, cost, and immune monitoring, will also be discussed.

MATERIALS AND METHODS

Databases such as PubMed, Scopus, and Web of Science, as well as additional online resources such as EBSCO, were exhaustively searched. Adult living-donor kidney transplant recipients who developed chimerism-based tolerance after concurrent bone marrow or hematopoietic stem cell transplantation or those who received non-chimerism-based, non-hematopoietic cell therapy using mesenchymal stromal cells, dendritic cells, or regulatory T cells were studied between 2000 and 2021. Individual sources of evidence were evaluated critically, and the strength of evidence and risk of bias for each outcome of the transplant tolerance study were assessed.

RESULTS

From 28,173 citations, 245 studies were retrieved after suitable exclusion and duplicate removal. Of these, 22 studies (2 RCTs, 11 cohort studies, 6 case-control studies, and 3 case reports) explicitly related to both interventions (chimerism- and non-chimerism-based immune tolerance) were used in the final review process and were critically appraised. According to the findings, chimerism-based strategies fostered immunotolerance, allowing for the safe withdrawal of immunosuppressive medications. Cell-based therapy, on the other hand, frequently did not induce tolerance except for minimising immunosuppression. As a result, the rejection rates, renal allograft function, and survival rates could not be directly compared between these two groups. While chimerism-based tolerance protocols posed safety concerns due to myelosuppression, including infections and graft-versus-host disease, cell-based strategies lacked these adverse effects and were largely safe. There was a lack of direct comparisons between HLA-identical and HLA-disparate recipients, and the cost implications were not examined in several of the retrieved studies. Most studies reported successful immunosuppressive weaning lasting at least 3 years (ranging up to 11.4 years in some studies), particularly with chimerism-based therapy, while only a few investigators used immune surveillance techniques. The studies reviewed were often limited by selection, classification, ascertainment, performance, and attrition bias.

CONCLUSIONS

This review demonstrates that chimerism-based hematopoietic strategies induce immune tolerance, and a substantial number of patients are successfully weaned off immunosuppression. Despite the risk of complications associated with myelosuppression. Non-chimerism-based, non-hematopoietic cell protocols, on the other hand, have been proven to facilitate immunosuppression minimization but seldom elicit immunological tolerance. However, the results of this review must be interpreted with caution because of the non-randomised study design, potential confounding, and small sample size of the included studies. Further validation and refinement of tolerogenic protocols in accordance with local practice preferences is also warranted, with an emphasis on patient selection, cost ramifications, and immunological surveillance based on reliable tolerance assays.

RGS1 Modulates Autophagic and Metabolic Programs and Is a Critical Mediator of Human Regulatory T Cell Function

Regulatory T cells (Tregs) are critical mediators of immune tolerance and play a diametric role in cancer and autoimmunity. Tumor-infiltrating Tregs are often associated with poor prognosis in solid tumors because their enrichment in the tumor microenvironment contributes to immunosuppression. Conversely, dysregulation in the Treg compartment can disrupt self-tolerance, leading to autoimmunity. In the present study, we describe what is, to our knowledge, a novel regulator of Tregs, the GTPase activator regulator of G protein 1 (RGS1), demonstrating that RGS1-deficient human Tregs show downregulation of Treg-associated genes and are less immunosuppressive. These RGS1-deficient Tregs exhibit perturbations to the FOXP3-c-MYC transcriptional axis and downstream metabolic and autophagy programs by shifting their energy demands toward glycolysis and rendering them less autophagic. Taken together, RGS1 may serve as an apical node of Treg function by regulating the FOXP3-c-MYC transcriptional axis, thereby providing a therapeutic rationale for targeting RGS1 for treatment of cancer and autoimmune diseases.

Changes in natural killer and T lymphocyte phenotypes in response to cardiovascular risk management

The pro-inflammatory and regulatory roles of T lymphocytes in atherosclerosis are well established but less is known about natural killer (NK) cells and natural killer T (NKT)-like cells. The effects of cardiovascular risk management on the phenotypes of these cells are unknown. To assess changes in NK cell and lymphocyte phenotypes and circulating inflammatory proteins in response to cardiovascular risk management in patients with carotid atherosclerosis. Fifty patients were included in a prospective clinical study. Measurements were at baseline and after 12 months of cardiovascular risk management. Circulating NK, NKT-like and T lymphocyte subpopulations were phenotyped by multi-colour flow cytometry. Proximity extension assay was performed for 176 plasma proteins associated with inflammation and cardiovascular disease. At 12 months there were significant reductions in LDL (P = 0.001) and blood pressure (P = 0.028). NK cells responded with a reduction in pro-inflammatory (NKG2C+) cells (P = 0.0003), an increase in anti-inflammatory (NKG2A+) cells (P = 0.032), and a reduction in terminally differentiated (CD57+) NK cells. NKT-like cells showed a similar decrease in terminally differentiated subpopulations (P = 0.000002). Subpopulations of T helper cells exhibited a significant reduction in central memory (P = 1.09 × 10-8) and a significant increase in CD4+ naïve- (P = 0.0008) and effector memory T cells (P = 0.006). The protein analysis indicated that cardiovascular risk management affects proteins involved in the inflammatory NF-κB pathway. The consistent decrease in senescent phenotypes of NK, NKT-like and CD4+ cells with a concomitant increase in more naïve, phenotypes suggests a change towards a less pro-inflammatory lymphocyte profile in response to cardiovascular risk management.Trial registry name: CARotid MRI of Atherosclerosis (CARMA). ClinicalTrials.gov identifier NCT04835571 (08/04/2021). https://www.clinicaltrials.gov/study/NCT04835571 .

Systems profiling reveals recurrently dysregulated cytokine signaling responses in ER+ breast cancer patients' blood

Cytokines mediate cell-to-cell communication across the immune system and therefore are critical to immunosurveillance in cancer and other diseases. Several cytokines show dysregulated abundance or signaling responses in breast cancer, associated with the disease and differences in survival and progression. Cytokines operate in a coordinated manner to affect immune surveillance and regulate one another, necessitating a systems approach for a complete picture of this dysregulation. Here, we profiled cytokine signaling responses of peripheral immune cells from breast cancer patients as compared to healthy controls in a multidimensional manner across ligands, cell populations, and responsive pathways. We find alterations in cytokine responsiveness across pathways and cell types that are best defined by integrated signatures across dimensions. Alterations in the abundance of a cytokine's cognate receptor do not explain differences in responsiveness. Rather, alterations in baseline signaling and receptor abundance suggesting immune cell reprogramming are associated with altered responses. These integrated features suggest a global reprogramming of immune cell communication in breast cancer.

Accumulation of immune-suppressive CD4 + T cells in aging - tempering inflammaging at the expense of immunity

The 'immune risk profile' has been shown to predict mortality in the elderly, highlighting the need to better understand age-related immune dysfunction. While aging leads to many defects affecting all arms of the immune system, this review is focused on the accrual of immuno-suppressive CD4 + T cell populations, including FoxP3 + regulatory T cells, and subsets of IL-10-producing T follicular helper cells. New data suggest that such accumulations constitute feedback mechanisms to temper the ongoing progressive low-grade inflammation that develops with age, the so-called "inflammaging", and by doing so, how they have the potential to promote healthier aging. However, they also impair effector immune responses, notably to infections, or vaccines. These studies also reinforce the idea that the aged immune system should not be considered as a poorly functional version of the young one, but more as a dynamic system in which CD4 + T cells, and other immune/non-immune subsets, differentiate, interact with their milieu and function differently than in young hosts. A better understanding of these unique interactions is thus needed to improve effector immune responses in the elderly, while keeping inflammaging under control.

Immunology and immunotherapy in gastric cancer

Gastric cancer is the fifth leading cause of cancer-related deaths worldwide. As the diagnosis of early gastric cancer is difficult, most patients are at a late stage of cancer progression when diagnosed. The current therapeutic approaches based on surgical or endoscopic resection and chemotherapy indeed improve patients' outcomes. Immunotherapy based on immune checkpoint inhibitors has opened a new era for cancer treatment, and the immune system of the host is reshaped to combat tumor cells and the strategy differs according to the patient's immune system. Thus, an in-depth understanding of the roles of various immune cells in the progression of gastric cancer is beneficial to application for immunotherapy and the discovery of new therapeutic targets. This review describes the functions of different immune cells in gastric cancer development, mainly focusing on T cells, B cells, macrophages, natural killer cells, dendritic cells, neutrophils as well as chemokines or cytokines secreted by tumor cells. And this review also discusses the latest advances in immune-related therapeutic approaches such as immune checkpoint inhibitors, CAR-T or vaccine, to reveal potential and promising strategies for gastric cancer treatment.

HIC1 interacts with FOXP3 multi protein complex: Novel pleiotropic mechanisms to regulate human regulatory T cell differentiation and function

Transcriptional repressor, hypermethylated in cancer 1 (HIC1) participates in a range of important biological processes, such as tumor repression, immune suppression, embryonic development and epigenetic gene regulation. Further to these, we previously demonstrated that HIC1 provides a significant contribution to the function and development of regulatory T (Treg) cells. However, the mechanism by which it regulates these processes was not apparent. To address this question, we used affinity-purification mass spectrometry to characterize the HIC1 interactome in human Treg cells. Altogether 61 high-confidence interactors were identified, including IKZF3, which is a key transcription factor in the development of Treg cells. The biological processes associated with these interacting proteins include protein transport, mRNA processing, non-coding (ncRNA) transcription and RNA metabolism. The results revealed that HIC1 is part of a FOXP3-RUNX1-CBFB protein complex that regulates Treg signature genes thus improving our understanding of HIC1 function during early Treg cell differentiation.

Reduction in regulatory T cells in preterm newborns is associated with necrotizing enterocolitis

BACKGROUND

Despite multifactorial pathogenesis, dysregulation of inflammatory immune response may play a crucial role in necrotizing enterocolitis (NEC). Regulatory T cells (Tregs) are involved in immune tolerance early in life. We aimed to investigate the predicting role of Tregs in developing NEC in neonates at high risk.

METHODS

We studied six newborns with a diagnosis of NEC (cases) in comparison with 52 controls (without NEC). We further classified controls as neonates with feeding intolerance (FI) and neonates without it (FeedTol). The rate of female and male neonates (sex defined as a biological attribute) was similar. We analyzed the blood frequency of Tregs (not overall numbers) at three time points: 0-3 (T0), 7-10 (T1), and 27-30 (T2) days after birth by flow cytometry. Neonates' sex was defined based on the inspection of external genitalia at birth.

RESULTS

We observed, at T0, a significantly lower frequency of Tregs in NEC cases (p < 0.001) compared with both FI (p < 0.01) and FeedTol controls (p < 0.01). Multivariate analysis reported that the occurrence of NEC was independently influenced by Treg frequency at birth (ß 2.98; p = 0.039).

CONCLUSION

Tregs frequency and features in the peripheral blood of preterm neonates, early in life, may contribute to identifying neonates at high risk of developing NEC.

IMPACT

Regulatory T cells may play a pivotal role in regulating the immune response in early life. Reduction of Tregs in early life could predispose preterm newborns to necrotizing enterocolitis. Early markers of necrotizing enterocolitis are still lacking. We demonstrated a predicting role of assessment of regulatory T cells in the diagnosis of this gastrointestinal emergency. Early identification of newborns at high risk of necrotizing enterocolitis through measurement of regulatory T cells may guide clinicians in the management of preterm newborns in order to reduce the development of this severe condition.

Expression characteristics of peripheral lymphocyte programmed death 1 and FoxP3+ Tregs in gastric cancer during surgery and chemotherapy

BACKGROUND

Programmed death 1 (PD-1) and CD4+CD25+FoxP3+ expression in peripheral blood T-cells has been previously reported in various types of cancer. However, the specific variation tendency during surgery and chemotherapy, as well as their relationship in gastric cancer patients, still remain unclear. Understanding this aspect may provide some novel insights for future studies on tumor recurrence and tumor immune escape, and also serve as a reference for determining the optimal timing and dose of clinical anti-PD-1 antibodies.

AIM

To observe and analyze the expression characteristics of peripheral lymphocyte PD-1 and FoxP3+ regulatory T cells (FoxP3+ Tregs) before and after surgery or chemotherapy in gastric cancer patients.

METHODS

Twenty-nine stomach cancer patients undergoing chemotherapy after a D2 gastrectomy provided 10 mL peripheral blood samples at each phase of the perioperative period and during chemotherapy. This study also included 29 age-matched healthy donors as a control group. PD-1 expression was detected on lymphocytes, including CD4+CD8+CD45RO+, CD4+CD45RO+, and CD8+CD45RO+ lymphocytes as well as regulatory T cells.

RESULTS

We observed a significant increase of PD-1 expression on immune subsets and a larger number of FoxP3+ Tregs in gastric cancer patients (P < 0.05). Following D2 gastrectomy, peripheral lymphocytes PD-1 expression and the number of FoxP3+ Tregs notably decrease (P < 0.05). However, during postoperative chemotherapy, we only observed a decrease in PD-1 expression on lymphocytes in the CD8+CD45RO+ and CD8+CD45RO+ populations. Additionally, linear correlation analysis indicated a positive correlation between PD-1 expression and the number of CD4+CD45RO+FoxP3high activated Tregs (aTregs) on the total peripheral lymphocytes (r = 0.5622, P < 0.0001).

CONCLUSION

The observed alterations in PD-1 expression and the activation of regulatory T cells during gastric cancer treatment may offer novel insights for future investigations into tumor immune evasion and the clinical application of anti-PD-1 antibodies in gastric cancer.

Memory regulatory T cells in pregnancy

Pregnancy requires the process of maternal immune tolerance to semi-allogeneic embryos. In contrast, an overreactive maternal immune system to embryo-specific antigens is likely to result in the rejection of embryos while damaging the invading placenta, such that the likelihood of adverse pregnancy outcomes can be increased. Regulatory T cells (Tregs) are capable of suppressing excessive immune responses and regulating immune homeostasis. When stimulating Tregs, specific antigens will differentiate into memory Tregs with long-term survival and rapid and powerful immune regulatory ability. Immunomodulatory effects mediated by memory Tregs at the maternal-fetal interface take on critical significance in a successful pregnancy. The impaired function of memory Tregs shows a correlation with various pregnancy complications (e.g., preeclampsia, gestational diabetes mellitus, and recurrent pregnancy losses). However, the differentiation process and characteristics of memory Tregs, especially their role in pregnancy, remain unclear. In this study, a review is presented in terms of memory Tregs differentiation and activation, the characteristics of memory Tregs and their role in pregnancy, and the correlation between memory Tregs and pregnancy complications. Furthermore, several potential therapeutic methods are investigated to restore the function of memory Tregs in accordance with immunopathologies arising from memory Tregs abnormalities and provide novel targets for diagnosing and treating pregnancy-associated diseases.

Ex vivo and in vivo evidence that cigarette smoke-exposed T regulatory cells impair host immunity against Mycobacterium tuberculosis

Introduction

A strong epidemiologic link exists between cigarette smoke (CS) exposure and susceptibility to tuberculosis (TB). Macrophage and murine studies showed that CS and nicotine impair host-protective immune cells against Mycobacterium tuberculosis (MTB) infection. While CS and nicotine may activate T regulatory cells (Tregs), little is known about how CS may affect these immunosuppressive cells with MTB infection.

Methods

We investigated whether CS-exposed Tregs could exacerbate MTB infection in co-culture with human macrophages and in recipient mice that underwent adoptive transfer of Tregs from donor CS-exposed mice.

Results

We found that exposure of primary human Tregs to CS extract impaired the ability of unexposed human macrophages to control an MTB infection by inhibiting phagosome-lysosome fusion and autophagosome formation. Neutralizing CTLA-4 on the CS extract-exposed Tregs abrogated the impaired control of MTB infection in the macrophage and Treg co-cultures. In Foxp3+GFP+DTR+ (Thy1.2) mice depleted of endogenous Tregs, adoptive transfer of Tregs from donor CS-exposed B6.PL(Thy1.1) mice with subsequent MTB infection of the Thy1.2 mice resulted in a greater burden of MTB in the lungs and spleens than those that received Tregs from air-exposed mice. Mice that received Tregs from donor CS-exposed mice and infected with MTB had modest but significantly reduced numbers of interleukin-12-positive dendritic cells and interferon-gamma-positive CD4+ T cells in the lungs, and an increased number of total programmed cell death protein-1 (PD-1) positive CD4+ T cells in both the lungs and spleens.

Discussion

Previous studies demonstrated that CS impairs macrophages and host-protective T effector cells in controlling MTB infection. We now show that CS-exposed Tregs can also impair control of MTB in co-culture with macrophages and in a murine model.

Tissue Resistance Decrease during Irreversible Electroporation of Pancreatic Cancer as a Biomarker for the Adaptive Immune Response and Survival

PURPOSE

To correlate irreversible electroporation (IRE) procedural resistance changes with survival outcomes and the IRE-induced systemic immune response in patients with locally advanced pancreatic cancer (LAPC).

MATERIALS AND METHODS

Data on IRE procedural tissue resistance (R) features and survival outcomes were collected from patients with LAPC treated within the context of 2 prospective clinical trials in a single tertiary center. Preprocedural and postprocedural peripheral blood samples were prospectively collected for immune monitoring. The change (ie, decrease) in R during the first 10 test pulses (ΔR10p) and during the total procedure (ΔRtotal) were calculated. Patients were divided in 2 groups on the basis of the median change in R (large ΔR vs small ΔR) and compared for differences in overall survival (OS) and progression-free survival and immune cell subsets.

RESULTS

A total of 54 patients were included; of these, 20 underwent immune monitoring. Linear regression modeling showed that the first 10 test pulses reflected the change in tissue resistance during the total procedure appropriately (P < .001; R2 = 0.91). A large change in tissue resistance significantly correlated with a better OS (P = .026) and longer time to disease progression (P = .045). Furthermore, a large change in tissue resistance was associated with CD8+ T cell activation through significant upregulation of Ki-67+ (P = .02) and PD-1+ (P = .047). Additionally, this subgroup demonstrated significantly increased expression of CD80 on conventional dendritic cells (cDC1; P = .027) and PD-L1 on immunosuppressive myeloid-derived suppressor cells (P = .039).

CONCLUSIONS

IRE procedural resistance changes may serve as a biomarker for survival and IRE-induced systemic CD8+ T cell and cDC1 activation.

Umbilical cord blood and peripheral blood-derived regulatory T cells therapy: Progress in type 1 diabetes

Regulatory T cells (Tregs) are key regulators for the inflammatory response and play a role in maintaining the immune tolerance. Type 1 diabetes (T1D) is a relatively common autoimmune disease that results from the loss of immune tolerance to β-cell-associated antigens. Preclinical models have demonstrated the safety and efficacy of Tregs given in transplant rejection and autoimmune diseases such as T1D. Adoptive transfer of Tregs has been utilized in clinical trials for over a decade. However, the achievement of the adoptive transfer of Tregs therapy in clinical application remains challenging. In this review, we highlight the characterization of Tregs and compare the differences between umbilical cord blood and adult peripheral blood-derived Tregs. Additionally, we summarize conditional modifications in the expansion of Tregs in clinical trials, especially for the treatment of T1D. Finally, we discuss the existing technical challenges for Tregs in clinical trials for the treatment of T1D.

The role of Th17 and Treg cells in normal pregnancy and unexplained recurrent spontaneous abortion (URSA): New insights into immune mechanisms

Recurrent spontaneous abortion (RSA) has various causes, including chromosomal abnormalities, a prethrombotic state, and abnormal uterine anatomical factors. However, in about 50% of cases, the cause remains unknown and is referred to as unexplained recurrent spontaneous abortion (URSA). The fetus is protected from rejection by the maternal system, acting as an allogeneic gene, and immune tolerance serves as a crucial mechanism. The Th17/Treg cell paradigm's emergence as a new subpopulation of CD4+ T cells, interacting with one another, plays an essential role in the immune microenvironment and the body's defense system. This Th17/Treg cell model helps to explain the pathology of recurrent miscarriage that could not be accounted for by the original immune mechanism based on the Th1/Th2 model. Furthermore, the plasticity of Th17 and Treg cells holds innovative significance in autoimmunity and abortion. This paper reviews the role of Th17/Treg cellular immune response in the maintaining normal pregnancy and understanding unexplained recurrent spontaneous abortion.

Exosomal PD-L1 derived from head and neck squamous cell carcinoma promotes immune evasion by activating the positive feedback loop of activated regulatory T cell-M2 macrophage

The positive feedback loop of activated regulatory T cells (aTregs) and M2 macrophages (M2) play a vital role in promoting the tumor immunosuppressive microenvironment of head and neck squamous cell carcinoma (HNSCC). However, the key factors regulating the positive feedback loop remain unclear. Herein, we investigated the effect of PD-L1 carried on exosomes derived from tumor cells (TEXs) on the aTreg-M2 positive feedback loop, as well as their role in mediating immunosuppression. In our study, TEXs with or without PD-L1 (TEX-PD-L1 or TEX-PD-L1KO) were treated with CD4+CD25- T cells and M0 macrophages, and the effect on the differentiation of aTregs, M2 and the aTreg-M2 positive feedback loop was assessed. TEXs carried more PD-L1 than tumor cells and not only promoted the differentiation of aTregs and M2, but also, most importantly, enhanced the positive feedback loop of aTreg-M2, which inhibited the proliferation of CD4+CD25- T cells and in turn led to tumor immune escape. Moreover, in vivo study showed that TEX-PD-L1KO could inhibit tumor growth and significantly improve the antitumor efficacy in both the peripheral and tumor microenvironments. Collectively this study revealed the role and mechanism of TEX-PD-L1 in negative immune regulation, and targeting TEX-PD-L1 may be a new idea and strategy for immunotherapy of HNSCC.

The immune imbalance between follicular regulatory and helper T cells in myelin oligodendrocyte glycoprotein IgG-associated disease

Myelin oligodendrocyte glycoprotein (MOG) antibody-associated disease (MOGAD) is a newly defined inflammatory demyelinating disease of the central nervous system. Currently, no immuno-modulatory treatment has been approved for MOGAD. We explored the function of follicular regularoty T (Tfr) and follicular helper T (Tfh) cells in patients with MOGAD. The number of circulating Tfr and Tfh cells and their expression of functional markers were accessed by flow cytometry. Circulating Tfr, Tfh, and B cells were further sorted and co-cultured in vitro to examine the influence of Tfr on Tfh-mediated B cell differentiation. In patients with MOGAD, the percentage of circulating PD-1hi Tfh cells elevated while the frequency of circulating activated Tfr cells decreased significantly. The Tfh/Tfr ratios positively correlated with the percentage of plasmblasts. In vitro, Tfh cells from patients with MOGAD exhibited a stronger capacity to promote the differentiation of plasmablasts through producing interleukin (IL)-21 than non-Tfh cells from patients, whereas Tfr cells suppressed this Tfh-mediated plasmablasts expansion, to a similar extent of IL-1 receptor antagonist (IL-1Ra). In conclusion, we revealed an immune imbalance of Tfr and Tfh cells in MOGAD. Tfr and IL-1Ra could be potential therapeutic targets in MOGAD.

Monitoring regulatory T cells as a prognostic marker in lung transplantation

Lung transplantation is the major surgical procedure, which restores normal lung functioning and provides years of life for patients suffering from major lung diseases. Lung transplant recipients are at high risk of primary graft dysfunction, and chronic lung allograft dysfunction (CLAD) in the form of bronchiolitis obliterative syndrome (BOS). Regulatory T cell (Treg) suppresses effector cells and clinical studies have demonstrated that Treg levels are altered in transplanted lung during BOS progression as compared to normal lung. Here, we discuss levels of Tregs/FOXP3 gene expression as a crucial prognostic biomarker of lung functions during CLAD progression in clinical lung transplant recipients. The review will also discuss Treg mediated immune tolerance, tissue repair, and therapeutic strategies for achieving in-vivo Treg expansion, which will be a potential therapeutic option to reduce inflammation-mediated graft injuries, taper the toxic side effects of ongoing immunosuppressants, and improve lung transplant survival rates.

Integrated analysis of phase 1a and 1b randomized controlled trials; Treg-targeted cancer immunotherapy with the humanized anti-CCR4 antibody, KW-0761, for advanced solid tumors

INTRODUCTION

Regulatory T cells (Tregs) have attracted attention as a novel therapeutic target to augment the clinical efficacy of immunotherapy. We conducted phase Ia and Ib trials to examine the safety and efficacy of the anti-CCR4 antibody, KW-0761 (mogamulizumab), which may eliminate effector Tregs (eTregs). We herein overviewed the results of these trials, presented cases with a durable clinical response, and investigated factors associated with the clinical effects of KW-0761.

METHODS

Forty-nine patients with CCR4-negative solid cancers were enrolled in the phase Ia and Ib trials on KW-0761. An integral analysis of safety, clinical responses, prognosis, blood laboratory data, and cancer testis antigen-specific immune responses was performed.

RESULTS

Grade 3-4 treatment-related adverse events were reported in 21 (42.9%) out of 49 patients, all of which were manageable. A partial response and stable disease were observed in 1 and 9 patients, respectively. A durable clinical response was noted in 2 esophageal and 2 lung cancer patients. eTreg depletion in peripheral blood was confirmed in most patients, and eTreg depletion was sustained during the KW-0761 treatment. High lymphocyte levels at baseline and 2 weeks after the initiation of KW-0761 were associated with a favorable clinical outcome.

CONCLUSIONS

A durable clinical response was noted in some patients, and high lymphocyte levels before treatment initiation may be a biomarker for the efficacy of KW-0761. The synergistic effect of KW-0761 for depleting Tregs and other immunotherapies is expected in the future.

Integrated BATF transcriptional network regulates suppressive intratumoral regulatory T cells

Human regulatory T cells (Tregs) are crucial regulators of tissue repair, autoimmune diseases, and cancer. However, it is challenging to inhibit the suppressive function of Tregs for cancer therapy without affecting immune homeostasis. Identifying pathways that may distinguish tumor-restricted Tregs is important, yet the transcriptional programs that control intratumoral Treg gene expression, and that are distinct from Tregs in healthy tissues, remain largely unknown. We profiled single-cell transcriptomes of CD4+ T cells in tumors and peripheral blood from patients with head and neck squamous cell carcinomas (HNSCC) and those in nontumor tonsil tissues and peripheral blood from healthy donors. We identified a subpopulation of activated Tregs expressing multiple tumor necrosis factor receptor (TNFR) genes (TNFR+ Tregs) that is highly enriched in the tumor microenvironment (TME) compared with nontumor tissue and the periphery. TNFR+ Tregs are associated with worse prognosis in HNSCC and across multiple solid tumor types. Mechanistically, the transcription factor BATF is a central component of a gene regulatory network that governs key aspects of TNFR+ Tregs. CRISPR-Cas9-mediated BATF knockout in human activated Tregs in conjunction with bulk RNA sequencing, immunophenotyping, and in vitro functional assays corroborated the central role of BATF in limiting excessive activation and promoting the survival of human activated Tregs. Last, we identified a suite of surface molecules reflective of the BATF-driven transcriptional network on intratumoral Tregs in patients with HNSCC. These findings uncover a primary transcriptional regulator of highly suppressive intratumoral Tregs, highlighting potential opportunities for therapeutic intervention in cancer without affecting immune homeostasis.