Overexpression of Potential Markers of Regulatory and Exhausted CD8+ T Cells in the Peripheral Blood Mononuclear Cells of Patients with B-Acute Lymphoblastic Leukemia.

B-acute lymphoblastic leukemia (B-ALL) is one of the most common pediatric cancers, wherein regulatory T cells (Treg) and exhausted CD8+ T cells may be important in its development and maintenance. In this bioinformatics study, we evaluated the expression of 20 Treg/CD8 exhaustion markers and their possible roles in patients with B-ALL. The mRNA expression values of peripheral blood mononuclear cell samples from 25 patients with B-ALL and 93 healthy subjects (HSs) were downloaded from publicly available datasets. Treg/CD8 exhaustion marker expression was normalized with that of the T cell signature and correlated with the expression of Ki-67, regulatory transcription factors (FoxP3, Helios), cytokines (IL-10, TGF-ß), CD8+ markers (CD8α chain, CD8ß chain), and CD8+ activation markers (Granzyme B, Granulysin). The mean expression level of 19 Treg/CD8 exhaustion markers was higher in the patients than in the HSs. In patients, the expression of five markers (CD39, CTLA-4, TNFR2, TIGIT, and TIM-3) correlated positively with Ki-67, FoxP3, and IL-10 expression. Moreover, the expression of some of them correlated positively with Helios or TGF-ß. Our results suggested that Treg/CD8+ T cells expressing CD39, CTLA-4, TNFR2, TIGIT, and TIM-3 favor B-ALL progression, and targeted immunotherapy against these markers could be a promising approach for treating B-ALL.

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.

Regulatory T cells in the peripheral blood of women with gestational diabetes: a systematic review and meta-analysis.

Background: Gestational diabetes (GDM) affects approximately 14% of pregnancies globally and is associated with short- and long-term complications for both the mother and child. In addition, GDM has been linked to chronic low-grade inflammation with recent research indicating a potential immune dysregulation in pathophysiology and a disparity in regulatory T cells. Objective: This systematic review and meta-analysis aimed to determine whether there is an association between GDM and the level of Tregs in the peripheral blood. Methods: Literature searches were conducted in PubMed, Embase, and Ovid between the 7th and 14th of February 2022. The inclusion criteria were any original studies published in the English language, measuring differentiated Tregs in women with GDM compared with glucose-tolerant pregnant women. Meta-analysis was performed between comparable Treg markers. Statistical tests were used to quantify heterogeneity: τ 2, χ 2, and I 2. Study quality was assessed using a modified version of the Newcastle-Ottawa scale. Results: The search yielded 223 results: eight studies were included in the review and seven in the meta-analysis (GDM = 228, control = 286). Analysis of Tregs across all trimesters showed significantly lower Treg numbers in women with GDM (SMD, -0.76; 95% CI, -1.37, -0.15; I 2 = 90%). This was reflected in the analysis by specific Treg markers (SMD -0.55; 95% CI, -1.04, -0.07; I 2 = 83%; third trimester, five studies). Non-significant differences were found within subgroups (differentiated by CD4+FoxP3+, CD4+CD127-, and CD4+CD127-FoxP3) of both analyses. Conclusion: GDM is associated with lower Treg numbers in the peripheral maternal blood. In early pregnancy, there is clinical potential to use Treg levels as a predictive tool for the subsequent development of GDM. There is also a potential therapeutic intervention to prevent the development of GDM by increasing Treg populations. However, the precise mechanism by which Tregs mediate GDM remains unclear. Systematic review registration: https://www.crd.york.ac.uk/prospero, identifier CRD42022309796.

Identification and classification of distinct surface markers of T regulatory cells.

Background: Regulatory T (Treg) cells have emerged as key players in the maintenance of immune homeostasis. Although significant progress has been made in recent years to define the Treg surface markers involved with or identifying their suppressive function, there remains much to be elucidated, and many questions persist. This study determined the expression of surface markers on human peripheral Treg cells and conventional T (Tconv) cells in a steady state and after activation to gain insight into their mechanism of action and more precisely characterize this regulatory population in humans. Methods: To screen Treg and Tconv cells, peripheral blood mononuclear cells (PBMCs) were isolated from volunteers, stained with a commercially available lyophilized antibody array comprising 371 surface antigens, and analyzed by flow cytometry. To compare Treg cells with activated Tconv cells, PBMCs were stimulated with PMA and further stained similar to freshly isolated cells. Results: Treg and Tconv cells were positive for 135 and 168 of the 371 antigens, respectively. Based on the frequency distribution, all of the most highly expressed markers identified were shared by both Treg and Tconv cells and participate in T cell activation, act as costimulatory and signaling molecules, or exhibit adhesion and migratory functions. Additionally, we identified several differences in marker expression between Treg and Tconv cells, with most found in the expression of co-stimulatory (ICOS, GITR, 4-1BB) and co-inhibitory (TIGIT, CTLA-4) molecules, as well as chemokine receptors (CXCR4, CXCR5, CCR4, CCR5, CCR7, CCR8, and CXCR7). Furthermore, post-activation expression of surface molecules identified molecules capable of discriminating Treg cells from activated Tconv cells (GITR, 4-1BB, TIGIT, CD120b, and CD39); however, almost all of these markers were also expressed in a small fraction of activated Tconv cells. Conclusions: These results offer insight into the biology of Tregs and contribute to their accurate identification and characterization in variety of immunological diseases as well as physiological processes.

Phenotypic alterations, clinical impact and therapeutic potential of regulatory T cells in cancer.

INTRODUCTION: Regulatory T cells (Tregs) have been characterised in different cancers. They accumulate in peripheral blood and tumour microenvironments where they suppress tumour-specific immune responses, enabling tumours to develop without challenge. This tumour immune evasion represents a major obstacle to successful cancer therapies. Whilst Tregs are generally divided into thymic-derived and peripherally induced, Tregs exhibit a wide spectrum of phenotypes and functional capacity dependent on microenvironment. This phenotypic diversity is also reflected in tumour-infiltrating Treg (TI Treg) populations, which may explain the variable impact of Treg accumulation on prognosis in different cancers. Identifying TI Treg subsets is critical to understand TI Treg biology and for developing effective immunotherapies. AREAS COVERED: This review discusses current and potential markers, and the modulation of these markers in cancer. In addition, we systematically review the clinical impact of Tregs in cancer and their potential as a therapeutic target, with a focus on TI Tregs. EXPERT OPINION: TI Tregs represent dynamic and diverse subsets that are key in promoting tumour progression through their suppressive activities. Targeting specific TI Treg subpopulations and functional TI Treg markers represents a feasible therapeutic strategy that might allow reestablishment of antitumour immune responses without affecting physiological immune regulation.