Cytotoxic CD4⁺ T cells (CD4⁺ CTLs) represent a novel subset of T cells with cytotoxic effects. They recognize target cells in an antigen-specific manner, relying on class II major histocompatibility complex (MHC-II) interactions. CD4⁺ CTLs exert cytotoxic effects on target cells by secreting cytotoxic molecules such as granzymes, perforin, and granulysin. Recent studies have revealed their significant roles in various autoimmune diseases. This review focuses on the differentiation, phenotypic characteristics, and roles of CD4⁺ CTLs in different types of autoimmune disorders, aiming to provide new insights for the prevention and treatment of these diseases.
Humans ; Autoimmune Diseases/immunology* ; CD4-Positive T-Lymphocytes/immunology* ; Animals ; T-Lymphocytes, Cytotoxic/immunology* ; Perforin/immunology* ; Granzymes/immunology*

OBJECTIVE: To investigate the expression of co-inhibitory molecules TIGIT/CD155 and PD-1 on CD4⁺T cells and Treg cells in peripheral blood of patients with chronic lymphocytic leukemia (CLL) and analyze their clinical significance. METHODS: The expression of PD-1 and TIGIT on CD4⁺T cells and Treg cells was detected by flow cytometry in 40 CLL patients and 20 healthy controls. Additionally, the expression of CD155 on peripheral blood B cells and DC cells of the enrolled subjects was detected. RESULTS: The proportions of PD-1⁺TIGIT⁺CD4⁺T cells, PD-1⁺TIGIT⁺Treg cells and CD155⁺DC cells in peripheral blood of CLL patients were significantly higher than those of healthy controls ( P < 0.05). The proportions of PD-1⁺TIGIT⁺CD4⁺T cells and PD-1⁺TIGIT⁺Treg cells in CLL patients were significantly higher than those of PD-1⁺TIGIT^-CD4⁺T cells and PD-1⁺TIGIT^-Treg cells, respectively ( P < 0.05). Both PD-1⁺TIGIT⁺CD4⁺T cells and PD-1⁺TIGIT⁺Treg cells were positively correlated with the level of CD155⁺DC cells (r =0.742, r =0.766). With the progression of Binet stage, the proportions of PD-1⁺TIGIT⁺CD4⁺T cells, PD-1⁺TIGIT⁺Treg cells, and CD155⁺DC cells gradually increased ( P < 0.05), and the aforementioned three types cells were all increased in patients with CD38≥30%, IGVH unmutated, or poor prognosis due to chromosomal abnormalities ( P < 0.05). CONCLUSION Co-inhibitory molecules PD-1 and TIGIT may be involved in immunodepletion in patients with advanced CLL, which has clinical prognostic value. Dual inhibitor molecular targeted therapy provides a new direction for the individualized treatment of CLL.
Humans ; Leukemia, Lymphocytic, Chronic, B-Cell/immunology* ; Receptors, Immunologic/metabolism* ; Programmed Cell Death 1 Receptor/metabolism* ; T-Lymphocytes, Regulatory/metabolism* ; Receptors, Virus/metabolism* ; CD4-Positive T-Lymphocytes/metabolism* ; Male ; Female ; Middle Aged ; Flow Cytometry ; Clinical Relevance

OBJECTIVES: To investigate the characteristics of immune cell infiltration in tumor samples from Chinese patients with clear cell renal cell carcinoma (ccRCC) and the correlation of immune cell infiltration with tumor stage and response to immunotherapy. METHODS: Tumor samples and clinicopathological data were collected from 154 ccRCC patients treated in Nanfang Hospital, Southern Medical University from October, 2020 to October, 2023. The immune cell types infiltrating the tumor tissues were identified using immunohistochemistry and immunofluorescence staining, and their correlations with the patients' clinicopathological characteristics were analyzed. Patient-derived tumor tissue fragment models (PDTF) models, constructed using tumor tissues from 22 patients, were treated with PD-1 monoclonal antibody, and T cell activation was detected using flow cytometry to assess the patients' responses to immunotherapy. RESULTS: In Chinese ccRCC patients included in this study, CD8⁺ T cells, CD4⁺ T cells, and CD3⁺ T cells were the most abundant in the tumor tissues. Higher infiltration levels of CD3⁺ T cells (P=0.004), PD-1⁺ T cells (P=0.020), CD68⁺ T cells (P=0.049), CD79⁺ T cells (P=0.049), and Tryptase⁺ cells (P=0.049) were all positively correlated with a larger tumor size (≥5 cm). A higher infiltration level of CD4⁺ T cells was associated with a lower tumor stage. Patients with higher International Society of Urological Pathology (ISUP) grades had higher infiltration levels of CD3⁺ T cells (P=0.023), CD8⁺ T cells (P=0.045), PD-1⁺ T cells (P=0.014), CD20⁺ B cells (P=0.020) and CD79⁺ B cells (P=0.049), and lower levels of Tryptase⁺ cells (P=0.001). Patients with abundant infiltrating immune cells tended to have better responses to immunotherapy. CONCLUSIONS The infiltrating immune cells are heterogeneous in Chinese ccRCC patients, and immune cell infiltration characteristics are closely correlated with clinicopathological parameters of the patients.
Humans ; Carcinoma, Renal Cell/pathology* ; Kidney Neoplasms/pathology* ; Immunotherapy ; Male ; Lymphocytes, Tumor-Infiltrating/immunology* ; Female ; Middle Aged ; CD8-Positive T-Lymphocytes/immunology* ; Aged ; T-Lymphocytes/immunology* ; Programmed Cell Death 1 Receptor/immunology* ; Adult ; CD4-Positive T-Lymphocytes/immunology* ; Neoplasm Staging

Infiltration and activation of peripheral immune cells are critical in the progression of multiple sclerosis and its experimental animal model, experimental autoimmune encephalomyelitis (EAE). This study investigates the role of high mobility group box 1 (HMGB1) in oligodendrocyte precursor cells (OPCs) in modulating pathogenic T cells infiltrating the central nervous system through the blood-brain barrier (BBB) by using OPC-specific HMGB1 knockout (KO) mice. We found that HMGB1 released from OPCs promotes BBB disruption, subsequently allowing increased immune cell infiltration. The migration of CD4+ T cells isolated from EAE-induced mice was enhanced when co-cultured with OPCs compared to oligodendrocytes (OLs). OPC-specific HMGB1 KO mice exhibited lower BBB permeability and reduced immune cell infiltration into the CNS, leading to less damage to the myelin sheath and mitigated EAE progression. CD4+ T cell migration was also reduced when co-cultured with HMGB1 knock-out OPCs. Our findings reveal that HMGB1 secretion from OPCs is crucial for regulating immune cell infiltration and provides insights into the immunomodulatory function of OPCs in autoimmune diseases.
Animals ; Encephalomyelitis, Autoimmune, Experimental/metabolism* ; HMGB1 Protein/deficiency* ; Mice, Knockout ; Oligodendrocyte Precursor Cells/immunology* ; Mice, Inbred C57BL ; CD4-Positive T-Lymphocytes/immunology* ; Cell Movement ; Blood-Brain Barrier/immunology* ; Mice ; Myelin Sheath/pathology* ; Disease Models, Animal ; Coculture Techniques ; Oligodendroglia/metabolism* ; Female ; Cells, Cultured

Objective To clarify the mechanism that HIV infection mediates mitochondrial damage of CD4⁺ T lymphocytes (CD4⁺ T cells) through mitogen-activated protein kinase (MAPK) pathway. Methods From October 1st, 2022 to March 31st, 2023, 47 HIV-infected people who received antiretroviral therapy (ART) for 4 years were recruited, including 22 immune non-responders (INR) and 25 responders (IR); and 26 sex and age-matched control participants (HC) who were negative for HCV, HBV, and HIV infections. The immune parameters were analyzed by flow cytometry. Finally, peripheral blood mononuclear cells (PBMCs) from HC or HIV patients were treated with MAPK pathway inhibitor SB203580, and the changes of mitochondrial function of CD4⁺ T cells were observed. Results Compared with HC group, the proportion of CD4⁺ T cells in PBMCs in INR group and IR group was significantly lower, and the proportion of CD4⁺ T cells in PBMCs in INR group was significantly lower than that in IR group. In addition, the proportion of naive (CD45RA⁺CD27⁺)T cells in PBMCs in INR group was significantly lower than that in HC group and IR group. Compared with HC group and IR group, the proportions of CD4⁺PD-1⁺, CD4⁺Av⁺ and CD4⁺MO⁺ in PBMCs in INR group and the proportions of CD45RA⁺CD27⁺PD-1⁺, CD45RA⁺CD27⁺Av⁺, CD45RA⁺CD27⁺MO⁺ in CD4⁺ T cell subsets increased significant. Compared with HC-con group, the basal respiration, maximal respiration and adenosine triphosphate(ATP) production of CD4⁺ T cells in HIV-con group decreased significantly, and JC-1 (green/red) in CD4⁺ T cells increased significantly. Compared with HIV-con group, the basal respiration, maximal respiration, ATP production and respiratory potential of CD4⁺ T cells in HIV-SB203580 group increased significantly, and the JC-1 (green/red) in CD4⁺ T cells decreased significantly. Conclusion Abnormal activation of the MAPK signaling pathway is observed in HIV patients receiving ART treatment, especially in CD4⁺ T cells of INR patients, which may lead to impaired mitochondrial function and abnormal CD4⁺ T cell homeostasis.
Humans ; HIV Infections/immunology* ; Male ; Mitochondria/drug effects* ; Female ; CD4-Positive T-Lymphocytes/metabolism* ; Adult ; Middle Aged ; MAP Kinase Signaling System/drug effects* ; Pyridines/pharmacology* ; Imidazoles/pharmacology* ; Leukocytes, Mononuclear/immunology*

Nucleolar complex associated 4 homolog (NOC4L) is a key factor in ribosome biogenesis, and this study aims to investigate its roles in activated T cells from the perspective of translation regulation. Firstly, flow cytometry was employed to determine the expression levels of NOC4L in the CD4⁺ T cells under different conditions in the transgenic reporter mice expressing Noc4l^mCherry. Subsequently, the expression of NOC4L along with cell proliferation was examined under Th1 and Th17 polarization conditions. Finally, in vitro experiments were conducted to identify the proteins interacting with NOC4L during the activation of Th1 and Th17 cells, on the basis of which the potential mechanisms of NOC4L were explored. The results showed that the expression level of NOC4L increased in activated CD4⁺ T cells, and the expression of NOC4L was closely associated with the proliferation and division of activated T cells. The in vitro experiments revealed interactions between NOC4L and proteins involved in ribosome assembly and cell proliferation during T cell activation. These findings lay a foundation for probing into the post-transcriptional regulation in helper T cells and hold profound significance for understanding the activation and regulatory mechanisms of T cells.
Animals ; Mice ; Lymphocyte Activation ; Cell Proliferation ; Mice, Transgenic ; Nuclear Proteins/genetics* ; Th1 Cells/immunology* ; Th17 Cells/metabolism* ; CD4-Positive T-Lymphocytes/immunology* ; Ribosomes/metabolism*

Animals ; Asthma/pathology* ; CD4-Positive T-Lymphocytes/immunology* ; China/epidemiology* ; Disease Models, Animal ; Immunoglobulin E/blood* ; Incidence ; Lung/pathology* ; Mice ; Pollen/chemistry* ; Populus/adverse effects* ; Prevalence

Age-associated changes in immune cells have been linked to an increased risk for infection. However, a global and detailed characterization of the changes that human circulating immune cells undergo with age is lacking. Here, we combined scRNA-seq, mass cytometry and scATAC-seq to compare immune cell types in peripheral blood collected from young and old subjects and patients with COVID-19. We found that the immune cell landscape was reprogrammed with age and was characterized by T cell polarization from naive and memory cells to effector, cytotoxic, exhausted and regulatory cells, along with increased late natural killer cells, age-associated B cells, inflammatory monocytes and age-associated dendritic cells. In addition, the expression of genes, which were implicated in coronavirus susceptibility, was upregulated in a cell subtype-specific manner with age. Notably, COVID-19 promoted age-induced immune cell polarization and gene expression related to inflammation and cellular senescence. Therefore, these findings suggest that a dysregulated immune system and increased gene expression associated with SARS-CoV-2 susceptibility may at least partially account for COVID-19 vulnerability in the elderly.
Adult ; Aged ; Aged, 80 and over ; Aging ; genetics ; immunology ; Betacoronavirus ; CD4-Positive T-Lymphocytes ; metabolism ; Cell Lineage ; Chromatin Assembly and Disassembly ; Coronavirus Infections ; immunology ; Cytokine Release Syndrome ; etiology ; immunology ; Cytokines ; biosynthesis ; genetics ; Disease Susceptibility ; Flow Cytometry ; methods ; Gene Expression Profiling ; Gene Expression Regulation, Developmental ; Gene Rearrangement ; Humans ; Immune System ; cytology ; growth & development ; immunology ; Immunocompetence ; genetics ; Inflammation ; genetics ; immunology ; Mass Spectrometry ; methods ; Middle Aged ; Pandemics ; Pneumonia, Viral ; immunology ; Sequence Analysis, RNA ; Single-Cell Analysis ; Transcriptome ; Young Adult

The 2019 novel coronavirus disease (COVID-19), caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has occurred in China and around the world. SARS-CoV-2-infected patients with severe pneumonia rapidly develop acute respiratory distress syndrome (ARDS) and die of multiple organ failure. Despite advances in supportive care approaches, ARDS is still associated with high mortality and morbidity. Mesenchymal stem cell (MSC)-based therapy may be an potential alternative strategy for treating ARDS by targeting the various pathophysiological events of ARDS. By releasing a variety of paracrine factors and extracellular vesicles, MSC can exert anti-inflammatory, anti-apoptotic, anti-microbial, and pro-angiogenic effects, promote bacterial and alveolar fluid clearance, disrupt the pulmonary endothelial and epithelial cell damage, eventually avoiding the lung and distal organ injuries to rescue patients with ARDS. An increasing number of experimental animal studies and early clinical studies verify the safety and efficacy of MSC therapy in ARDS. Since low cell engraftment and survival in lung limit MSC therapeutic potentials, several strategies have been developed to enhance their engraftment in the lung and their intrinsic, therapeutic properties. Here, we provide a comprehensive review of the mechanisms and optimization of MSC therapy in ARDS and highlighted the potentials and possible barriers of MSC therapy for COVID-19 patients with ARDS.
Adoptive Transfer ; Alveolar Epithelial Cells ; pathology ; Animals ; Apoptosis ; Betacoronavirus ; Body Fluids ; metabolism ; CD4-Positive T-Lymphocytes ; immunology ; Clinical Trials as Topic ; Coinfection ; prevention & control ; therapy ; Coronavirus Infections ; complications ; immunology ; Disease Models, Animal ; Endothelial Cells ; pathology ; Extracorporeal Membrane Oxygenation ; Genetic Therapy ; methods ; Genetic Vectors ; administration & dosage ; therapeutic use ; Humans ; Immunity, Innate ; Inflammation Mediators ; metabolism ; Lung ; pathology ; physiopathology ; Mesenchymal Stem Cell Transplantation ; methods ; Mesenchymal Stem Cells ; physiology ; Multiple Organ Failure ; etiology ; prevention & control ; Pandemics ; Pneumonia, Viral ; complications ; immunology ; Respiratory Distress Syndrome, Adult ; immunology ; pathology ; therapy ; Translational Medical Research

Biomarkers ; metabolism ; CD4-Positive T-Lymphocytes ; immunology ; metabolism ; Cytomegalovirus Retinitis ; immunology ; Female ; Humans ; Male ; Polymerase Chain Reaction ; Precursor Cell Lymphoblastic Leukemia-Lymphoma ; immunology ; metabolism ; virology