Generation and Immune Regulation of CD4+CD25-Foxp3+ T Cells in Chronic Obstructive Pulmonary Disease

Assessing the causal relationship between immune cell traits and depression by Mendelian randomization analysis

BACKGROUND

Observational studies suggested that immune system disorder is associated with depression. However, the causal association has not been fully elucidated. Thus, we aim to assess the causality of the associations of immune cell profiles with risk of depression through Mendelian randomization analysis.

METHODS

We extracted genetic variances of immune cell traits from a large publicly available genome-wide association study (GWAS) involving 3757 participants and depression from a GWAS containing 246,363 cases and 561,190 controls of European ancestry. Inverse variance weighting (IVW) was performed as the MR primary analysis. Simultaneously apply MR-Egger and weighted median as supplementary enhancements to the final result. We further performed heterogeneity and horizontal pleiotropy test to validate the main MR results.

RESULTS

Five immunophenotypes were identified to be significantly associated with depression risk: CD27 on IgD-CD38dimB cell (OR = 1.019, 95 % CI = 1.010-1.028, P = 1.24 × 10-5), CD45RA-CD4+T cell Absolute Count (OR = 0.974, 95 % CI = 0.962-0.986, P = 3.88 × 10-5), CD40 on CD14-CD16+monocyte (OR = 0.987, 95 % CI = 0.981-0.993, P = 2.1 × 10-4), CD27 on switched memory B cell (OR = 1.015, 95 % CI = 1.006-1.023, P = 2.6 × 10-4), CD27 on IgD-CD38-B cell (OR = 1.017, 95 % CI = 1.008-1.027, P = 3.1 × 10-4).

CONCLUSION

Our findings shed light on the intricate interaction pattern between the immune system and depression, offering a novel direction for researchers to investigate the underlying biological mechanisms of depression.

Identification of related-genes of T cells in lung tissue of chronic obstructive pulmonary disease based on bioinformatics and experimental validation

T cells are one of the main cell types shaping the immune microenvironment in chronic obstructive pulmonary disease (COPD). They persist andplay cytotoxic roles. The purpose of this study aimed to explore the potential related-genes of T cells in lung tissue of COPD. Chip data GSE38974 and single_celldata GSE196638 were downloaded from the GEO database. Difference analyses and WGCNA of GSE38974 were performed to identify DEGs and the modules most associated with the COPD phenotype. Various cell subsets were obtained by GSE196638, and DEGs of T cells were further identified. GO, GSEA and KEGG enrichment analyses were conducted to explore the biological functions and regulatory signaling pathways of the DEGs and DEGs of T cells. The intersection of the DEGs, module genes and DEGs of T cells was assessed to acquire related-genes of T cells. The mRNA and protein expression levels of related-genes ofT cells were verified in lung tissue of mouse with emphysema model. Based on GSE38974 difference analysis, 3811 DEGs were obtained. The results of WGCNA showed that the red module had the highest correlation coefficient with the COPD phenotype. GSE196638 analysis identified 124 DEGs of T cells. The GO, GSEAand KEGG enrichment analyses mainly identified genes involved in I-kappaB kinase/NF-kappaB signaling, receptor signaling pathway via STAT, regulationof CD4-positive cells, regulation of T-helper cell differentiation, chemokine signaling pathway, Toll-likereceptor signaling pathway, CD8-positive cells, alpha-beta T cell differentiation, MAPK signaling pathway and Th17 cell differentiation. The DEGs, genes of the red module and DEGs of T cells were overlapped to acquire FOXO1 and DDX17. The results of RT-qPCR and Western Blot indicate that the mRNA and protein expression levels of FOXO1 and DDX17 in lung tissue of emphysema mice were significantly higher compared with those in air-exposed mice. FOXO1 as well as DDX17 may be related-genesof T cells in lung tissue of patient with COPD, and their participation in the biological processes of different signaling pathways may inspire further COPD research.

TIGIT Regulates T Cell Inflammation in Airway Inflammatory Diseases

TIGIT, a co-inhibitory receptor found on T cells and NK cells, transmits inhibitory signals upon binding to its ligand. This interaction suppresses the activation of various signaling pathways, leading to functional exhaustion of cells, ultimately dampening excessive inflammatory responses or facilitating immune evasion in tumors. Dysregulated TIGIT expression has been noted in T cells across different inflammatory conditions, exhibiting varying effects based on T cell subsets. TIGIT predominantly restrains the effector function of pro-inflammatory T cells, upholds the suppressive function of regulatory T cells, and influences Tfh maturation. Mechanistically, the IL27-induced transcription factors c-Maf and Blimp-1 are believed to be key regulators of TIGIT expression in T cells. Notably, TIGIT expression in T cells is implicated in lung diseases, particularly airway inflammatory conditions such as lung cancer, obstructive pulmonary disease, interstitial lung disease, sarcoidosis, and COVID-19. This review emphasizes the significance of TIGIT in the context of T cell immunity and airway inflammatory diseases.

Ginseng Saponin Rb1 Attenuates Cigarette Smoke Exposure-Induced Inflammation, Apoptosis and Oxidative Stress via Activating Nrf2 and Inhibiting NF-κB Signaling Pathways

Objective

Cigarette smoke exposure is one of the major risk factors for the development of chronic obstructive pulmonary disease (COPD). Ginseng saponin Rb1 (Rb1) is a natural extract from ginseng root with anti-inflammatory and anti-oxidant effects. However, the underlying mechanism of the Rb1 in COPD remains unknown. Therefore, we sought to explore the role of Rb1 in cigarette smoke-induced damage and to reveal the potential mechanism.

Methods

The cell viability and lactose dehydrogenase (LDH) activity were analyzed using cell counting kit-8 (CCK-8) and LDH release assays. We further investigated the inflammation, apoptosis and oxidative stress markers and analyzed the nuclear factor-kappa B (NF-κB) and nuclear factor erythroid-2-related factor 2 (Nrf2) pathways in BEAS-2B cells and COPD rat model following cigarette smoke extract (CSE) exposure.

Results

Our results showed that CSE promoted inflammation, apoptosis and oxidative stress in BEAS-2B cells. Rb1 suppressed the inflammatory response by inhibiting expression of pro-inflammatory cytokines such as tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6) and IL-1β and inhibiting the NF-κB signaling pathway. Rb1 possessed the ability to hinder cell apoptosis induced by CSE. In addition, Rb1 concurrently reduced CSE-induced oxidative reactions and promoted Nrf2 translocation to nucleus. For in vivo study, Rb1 treatment alleviated CSE-induced lung injury, apoptosis, reactive oxygen species (ROS) release and inflammatory reactions. Also, Rb1 treatment activated Nrf2 signaling and inactivated NF-κB signaling in COPD rats.

Conclusion

Rb1 attenuates CSE-induced inflammation, apoptosis and oxidative stress by suppressing NF-κB and activating Nrf2 signaling pathways, which provides novel insights into the mechanism underlying CSE-induced COPD.

Role of Th17 cells, Treg cells, and Th17/Treg imbalance in immune homeostasis disorders in patients with chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is the third leading cause of death worldwide, following strokes and cardiovascular diseases. Chronic lung inflammation is believed to play a role in the development of COPD. In addition, accumulating evidence shows that the immune system plays a crucial role in the pathogenesis of COPD. Significant advancements have been made in research on the pathogenesis of immune diseases and chronic inflammation in recent years, and T helper 17 (Th17) cells and regulatory T (Treg) cells have been found to play a crucial role in the autoimmune response. Th17 cells are a proinflammatory subpopulation that causes autoimmune disease and tissue damage. Treg cells, on the other hand, have a negative effect but can contribute to the occurrence of the same disease when their antagonism fails. This review mainly summarizes the biological characteristics of Th17 cells and Treg cells, their roles in chronic inflammatory diseases of COPD, and the role of the Th17/Treg ratio in the onset, development, and outcome of inflammatory disorders, as well as recent advancements in immunomodulatory treatment targeting Th17/Treg cells in COPD.

Reduced frequencies of Foxp3+GARP+ regulatory T cells in COPD patients are associated with multi-organ loss of tissue phenotype

Background

Expression of glycoprotein A dominant repeat (GARP) has been reported to occur only in activated human naturally occurring regulatory T cells (Tregs) and their clones, and not in activated effector T cells, indicating that GARP is a marker for bona fide Tregs. A different phenotype of chronic obstructive pulmonary disease (COPD) may have a different immunologic mechanism.

Objective

To investigate whether the distribution of Tregs defined by GARP is related to the multi-organ loss of tissue phenotype in COPD.

Methods

GARP expression on T cells from peripheral blood and bronchoalveolar lavage (BAL) collected from patients with COPD was examined by flow cytometry. The correlation of GARP expression to clinical outcomes and clinical phenotype, including the body mass index, lung function and quantitative computed tomography (CT) scoring of emphysema, was analyzed.

Results

Patients with more baseline emphysema had lower forced expiratory volume, body mass index (BMI), worse functional capacity, and more osteoporosis, thus, resembling the multiple organ loss of tissue (MOLT) phenotype. Peripheral Foxp3⁺GARP⁺ Tregs are reduced in COPD patients, and this reduction reversely correlates with quartiles of CT emphysema severity in COPD. Meanwhile, the frequencies of Foxp3⁺GARP⁻ Tregs, which are characteristic of pro-inflammatory cytokine production, are significantly increased in COPD patients, and correlated with increasing quartiles of CT emphysema severity in COPD. Tregs in BAL show a similar pattern of variation in peripheral blood.

Conclusion

Decreased GARP expression reflects more advanced disease in MOLT phenotype of COPD. Our results have potential implications for better understanding of the immunological nature of COPD and the pathogenic events leading to lung damage.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12931-022-02099-2.

Immunophenotype in acute exacerbation of chronic obstructive pulmonary disease: a cross-sectional study

Background

Chronic obstructive pulmonary disease (COPD) is a heterogeneous disease, and the immune inflammatory response is thought to play an important role in pathogenesis. However, the immunophenotype of patients with COPD is unknown. Herein, we evaluated the immunophenotype of patients with acute exacerbation of COPD (AECOPD).

Methods

A cross-sectional study was conducted in West China Hospital from September 2018 to October 2019. The proportion of CD4 + T lymphocyte subtypes (Th1, Th2, Th17 and Treg) and levels of serum cytokines in the peripheral blood of patients with AECOPD, stable COPD (SCOPD), healthy smokers (HSs)and healthy controls (HCs) were evaluated.

Results

A total of 15 HCs, 19 HSs, 42 patients with SCOPD, and 55 patients with AECOPD were included. Compared to patients with SCOPD, Th1 cells, Th17 cells, Treg cell ratio, Th1/Th2 cell ratio, and the levels of C-reactive protein, interleukin (IL)-6, and IL-10 were significantly increased in patients with AECOPD (P < 0.001), while the proportion of Th2 cells was significantly reduced (P < 0.01). The proportion of Th17 cells was positively correlated with COPD Assessment Test score (r = 0.266, P = 0.009), modified Medical Research Council dyspnea score (r = 0.858, P < 0.0001), and Th1 cell ratio (r = 0.403, P < 0.0001) and negatively correlated with forced vital capacity (r = − 0.367, P = 0.009) and proportion of Th2 cells (r = − 0.655, P < 0.0001).

Conclusions

The immunophenotype of patients with AECOPD shows abnormal activation of Th1, Th17, and Treg cells. There is a correlation between the proportion of Th17 cells and the severity of COPD; therefore, this may represent a novel index for the evaluation of COPD severity.

Trial registration: China Clinical Trials Registry, ChiCTR1800018452, registered 19 September 2018, https://www.chictr.org.cn/index.aspx.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12931-022-02058-x.

PD-L1 signaling selectively regulates T cell lymphatic transendothelial migration

Programmed death-1 (PD-1) and its ligand PD-L1 are checkpoint molecules which regulate immune responses. Little is known about their functions in T cell migration and there are contradictory data about their roles in regulatory T cell (Treg) function. Here we show activated Tregs and CD4 effector T cells (Teffs) use PD-1/PD-L1 and CD80/PD-L1, respectively, to regulate transendothelial migration across lymphatic endothelial cells (LECs). Antibody blockade of Treg PD-1, Teff CD80 (the alternative ligand for PD-L1), or LEC PD-L1 impairs Treg or Teff migration in vitro and in vivo. PD-1/PD-L1 signals through PI3K/Akt and ERK to regulate zipper junctional VE-cadherin, and through NFκB-p65 to up-regulate VCAM-1 expression on LECs. CD80/PD-L1 signaling up-regulates VCAM-1 through ERK and NFκB-p65. PD-1 and CD80 blockade reduces tumor egress of PD-1high fragile Tregs and Teffs into draining lymph nodes, respectively, and promotes tumor regression. These data provide roles for PD-L1 in cell migration and immune regulation.

The Role of Human Leukocyte Antigen-DR in Regulatory T Cells in Patients with Virus-Induced Acute Exacerbation of Chronic Obstructive Pulmonary Disease

Background

This study assessed the role of different immune phenotypes of T cells in virus-induced acute exacerbation of chronic obstructive pulmonary disease (AECOPD).

Material/Methods

The study involved 103 participants, including individuals with virus-induced AECOPD (n=32), non-virus-induced AECOPD (n=31), and stable COPD (n=20) and individuals who were healthy smokers (n=20). The immune phenotypes of T cells in peripheral blood were evaluated via flow cytometry analysis, and the differences were analyzed.

Results

Patients with virus-induced AECOPD (virus group) had a higher COPD assessment test score on admission than those in the group with non-virus-induced AECOPD (nonvirus group; 25.6±3.8 vs 21.9±4.8, P=0.045). A lower CD4⁺ human leukocyte antigen-DR (HLA-DR)⁺ frequency was found in the peripheral blood of the virus group compared with the nonvirus group (2.2 vs 4.2, P=0.015), and the frequency of CD4⁺ CD25^high CD127^low HLA-DR⁺ in CD4⁺ in the virus group was lower than in the nonvirus group (1.1 vs 3.6, P=0.011). The CD3⁺, CD4⁺, CD8⁺, CD4⁺ central memory T cell, CD4⁺ effector memory T cell (Tem), CD4⁺ end-stage T cell, and CD8⁺ Tem levels in lymphocytes of peripheral blood were lower in exacerbation groups relative to those in the stable COPD and healthy smoking groups, but similar between exacerbation groups. Similar frequencies and levels of T cells between different stagings of COPD were also identified.

Conclusions

The expression of HLA-DR on the cell surface of CD4⁺ regulatory T cells (Tregs) was lower in the peripheral blood of patients with virus-induced AECOPD. The expression of HLA-DR in CD4⁺ Tregs suggested the effect of respiratory viruses on adaptive immunity of patients with AECOPD to some extent.

T cell responses in respiratory viral infections and chronic obstructive pulmonary disease

ABSTRACT

Respiratory viruses are major human pathogens that cause approximately 200 million pneumonia cases annually and induce various comorbidities with chronic obstructive pulmonary disease (COPD), resulting in significant health concerns and economic burdens. Clinical manifestations in respiratory viral infections and inflammations vary from asymptomatic, mild, to severe, depending on host immune cell responses to pathogens and interactions with airway epithelia. We critically review the activation, effector, and regulation of T cells in respiratory virus infections and chronic inflammations associated with COPD. Crosstalk among T cells, innate immune cells, and airway epithelial cells is discussed as essential parts of pathogenesis and protection in viral infections and COPD. We emphasize the specificity of peptide antigens and the functional heterogeneity of conventional CD4+ and CD8+ T cells to shed some light on potential cellular and molecular candidates for the future development of therapeutics and intervention against respiratory viral infections and inflammations.

Sex and FOXP3 gene rs2232365 polymorphism may be associated with the clinical and pathological aspects of chronic viral diseases

Background

The forkhead box protein 3 (FOXP3) transcription factor is one of the main markers of immunological suppression in different pathological profiles, and the presence of polymorphic variants may alter the gene expression of this factor. Despite descriptions of an association between the presence of the rs2232365 polymorphism and chronic diseases, the role of the sex variant in this context has not yet been elucidated, as the FOXP3 gene is located on the human sex chromosome X.

Results

To contribute to this topic, 323 women and 373 men were enrolled in the study, of which 101 were diagnosed with chronic viral liver diseases (39 women and 62 men), 67 with HTLV-1 infection (44 women and 23 men), 230 with coronary artery disease (91 women and 139 men) and 298 healthy and uninfected blood donors (149 women and men). They were genotyped for the rs2232365 polymorphism. The rs2232365 polymorphism was associated with clinical and pathological aspects and biomarkers of viral infections only in men, with functional differences between different infections.

Conclusions

A relationship is suggested between sex and FOXP3 rs2232365 polymorphism, resulting in different biological repercussions.

Semaphorin 4D Induces an Imbalance of Th17/Treg Cells by Activating the Aryl Hydrocarbon Receptor in Ankylosing Spondylitis

Objectives

Semaphorin 4D (Sema4D) is constitutively expressed on T cells and osteoclasts, and regulates T cell proliferation and bone remodeling. In addition, several studies have shown that Sema4D is involved in the pathogenesis of autoimmunity. We undertook this study to investigate the mechanism by which Sema4D affects the pathogenic progress of ankylosing spondylitis (AS).

Methods

Soluble Sema4D (sSema4D) levels in serum were analyzed by enzyme-linked immunosorbent assay. The cell surface levels and transcripts of Sema4D were evaluated in CD4 + and CD19 + cells from the AS patients and healthy individuals. The mRNA expression levels were assessed by quantitative polymerase chain reaction (qPCR). The proportions of Treg cells and IL-17-producing T-cells (Th17 cells) differentiated from CD4 + T cells were analyzed by flow cytometric analysis. The aryl hydrocarbon receptor (AhR) agonistic effect of Sema4D was detected by analyzing the activation of downstream signaling pathways and target genes using Luciferase and EROD assay.

Results

Levels of sSema4D were elevated in both serum from AS patients, and clinical features markers were correlated with serum sSema4D levels. Sema4D facilitated CD4 + T cells proliferation and Th17 cells differentiation and inhibited Treg cells differentiation by enhancing RORγt expression and reducing Foxp3 expression, with increasing expression and secretion of IL-17 and IL-22. It induced the expression and activity of AhR target gene CYP1A1 and XRE reporter activity via interaction with CD72.

Conclusion

These findings indicate that Sema4D as a potent activator of T cells in the immune response contributes to the inflammation of AS by inducing imbalance in Th17 and Treg cell populations in an AhR-dependent manner, suggesting it is a crucial participant in AS pathogenesis.

Lung adenocarcinoma-related TNF-α-dependent inflammation upregulates MHC-II on alveolar type II cells through CXCR-2 to contribute to Treg expansion

MHC-II on alveolar type-II (AT-II) cells is associated with immune tolerance in an inflammatory microenvironment. Recently, we found TNF-α upregulated MHC-II in AT-II in vitro. In this study, we explored whether TNF-α-mediated inflammation upregulates MHC-II on AT-II cells to trigger Treg expansion in inflammation-driven lung adenocarcinoma (IDLA). Using urethane-induced mice IDLA model, we found that IDLA cells mainly arise from AT-II cells, which are the major source of MHC-II. Blocking urethane-induced inflammation by TNF-α neutralization inhibited tumorigenesis and reversed MHC-II upregulation on tumor cells of AT-II cellular origin in IDLA. MHC-II-dependent AT-II cells were isolated from IDLA-induced Treg expansion. In human LA samples, we found high expression of MHC-II in tumor cells of AT-II cellular origin, which was correlated with increased Foxp3⁺ T cells infiltration as well as CXCR-2 expression. CXCR-2 and MHC-II colocalization was observed in inflamed lung tissue and IDLA cells of AT-II cellular origin. Furthermore, at the pro-IDLA inflammatory stage, TNF-α-neutralization or CXCR-2 deficiency inhibited the upregulation of MHC-II on AT-II cells in inflamed lung tissue. Thus, tumor cells of AT-II cellular origin contribute to Treg expansion in an MHC-II-dependent manner in TNF-α-mediated IDLA. At the pro-tumor inflammatory stage, TNF-α-dependent lung inflammation plays an important role in MHC-II upregulation on AT-II cells.

CD4+CD25-FoxP3+ T cells: a distinct subset or a heterogeneous population?

In addition to generating effective immunity against infectious agents, the immune system helps to fight against different noninfectious human diseases while maintaining the balance between self and non-self discrimination. The breakdown of tolerance in autoimmune diseases or sustainable tolerance in an abnormal microenvironment such as chronic inflammation may initiate the process of malignancy. Immune system regulation is controlled by a complex, dynamic network of cells and mediators. Understanding the cellular and molecular basis of immune regulation provides better insight into the mechanisms governing the immune pathology of diseases. Among several cellular subsets and mediators with regulatory roles, a subpopulation of CD4⁺ T cells was recently reported to be positive for FoxP3 and negative for CD25, with a suggested range of functional activities in both cancer and autoimmune diseases. This CD4 subset was first reported in 2006 and thought to have a role in the pathogenesis of cancer. However, the spectrum of roles played by this T cell subset is broad, and no consensus has been reached regarding its immunological functions. In this review, we focused on the possible origin of CD4⁺CD25^‒FoxP3⁺ T cells and their function in cancer and autoimmune diseases.

Role of Regulatory T Cells in Disturbed Immune Homeostasis in Patients With Chronic Obstructive Pulmonary Disease

Chronic obstructive pulmonary disease (COPD) is a complex chronic disease in which T cell-mediated pulmonary inflammation has been shown to play a key role. Accumulating evidence shows that COPD has many of the characteristics of an autoimmune response. An adaptive immune response directed against lung self-antigens, which are released during the initial innate inflammatory response and are triggered by constant exposure to cigarette smoke and epithelial injury, drives the persistent inflammatory response found in smokers. The development and severity of adaptive inflammation depend on the level of tolerance to self-antigens. For these reasons, the effect of regulatory T (Treg) cells on adaptive immunity in COPD patients is of particular interest and could be targeted therapeutically. The disturbance in immune homeostasis caused by changes in the number or function of Treg cells, which is related to cigarette smoke exposure, may be of importance in understanding the development and progression of COPD.

Immunoregulatory role of IL-2/STAT5/CD4+CD25+Foxp3 Treg pathway in the pathogenesis of chronic osteomyelitis

Background

This study aimed to investigate immunoregulatory role of IL-2/STAT5/CD4+CD25+Foxp3 Treg pathway in pathogenesis of chronic osteomyelitis (COM).

Methods

Sprague-Dawley (SD) rats were injected with Staphylococcus aureus to establish COM model. 4 weeks later, the lesioned bones were collected and subjected to HE staining for examination of inflammatory infiltration. Enzyme-linked immunosorbent assay (ELISA) was employed to detect IL-2 expression in peripheral blood; flow cytometry was performed to detect CD25+CD4+Foxp3 Treg cells in peripheral blood. The mRNA expression of Foxp3 and CTLA-4 was detected by RT-PCR and the protein expression of STAT5 and p-STAT5 was detected by Western Blotting in CD25+CD4+Foxp3 Treg cells.

Results

In COM group, the periosteal thickening was observed in femur, and there were a large number of inflammatory cells in medullary cavity, accompanied by bone destruction. At 1, 2 and 4 weeks, IL-2 expression significantly increased, the proportion of CD4+CD25+FoxP3 Treg cells in peripheral monocytes markedly increased, the mRNA expression of Foxp3 and CTLA-4 and p-STAT5 protein expression increased dramatically in Treg cells as compared to control group (P<0.001).

Conclusions

IL-2/STAT5/CD4+CD25+Foxp3 Treg pathway may be involved in the pathogenesis of COM, and excessive immunosuppression may lead to persistent infectious inflammation, which may become a key target for future treatment of COM.

Peripheral blood CD4+ T cell populations by CD25 and Foxp3 expression as a potential biomarker: reflecting inflammatory activity in chronic obstructive pulmonary disease

Background

The temporally dynamic changes of CD25 and Foxp3 expression in CD4+ T cells are initiated by T cell receptor (TCR) signals strength or frequency. There is a deficiency of peripheral markers for assessing COPD activity, and the current study was conducted to explore whether peripheral CD4+ T cell populations based on CD25 and Foxp3 expression could serve as an indicator for COPD inflammatory activity.

Methods

The distribution and phenotypic characteristics of CD4+CD25±Foxp3± T cells from peripheral blood in different populations were determined by flow cytometry. The model for the differentiation of CD4+ T cells populations by CD25 and Foxp3 expression was explored in vitro.

Results

The frequencies of peripheral CD4+CD25+Foxp3- T cells and CD4+CD25+Foxp3+ T cells were increased in AECOPD patients, whereas the frequency of CD4+CD25-Foxp3+ T cells was increased in SCOPD patients without receiving systemic treatment. Phenotypic analysis revealed that CD4+CD25+Foxp3- T cells, CD4+CD25+Foxp3+ T cells and CD4+CD25-Foxp3+ T cells had received antigenic stimulation and resembled central memory or effector memory T cells. The differentiation of CD4+ T cells populations by CD25 and Foxp3 expression was dictated by TCR signals. The paired study indicated that the frequencies of CD4+CD25+Foxp3- T cells, CD4+CD25+Foxp3+ T cells and CD4+CD25- Foxp3+ T cells were decreased while the frequency of CD4+CD25-Foxp3- T cells were increased in the same patients from AECOPD to convalescence.

Conclusions

Collectively, we propose that the dynamic changes of CD4+ T cell populations by CD25 and Foxp3 expression could function as potential biomarkers for reflecting inflammatory activity in COPD.