BACKGROUND: Regulatory dendritic cell (DCreg) subset exhibits a unique capacity for inducing immune tolerance among the variety subsets of dendritic cells (DCs) within gut-associated lymphoid tissues (GALTs). Fms-like tyrosine kinase 3 ligand (FLT3L) is involved in the differentiation of DCregs and the subsequent expansion of regulatory T-cells (Tregs) mediated by DCregs, though the precise mechanism remains poorly understood. This study aimed to explore the expansion mechanism of Treg induced by DCreg and the role of FLT3L in this process. METHODS: DCregs were distinguished from other DC subsets isolated from GALTs of BALB/c mice through a mixed lymphocyte reaction assay. The functions and mechanisms by which FLT3L promoted Treg expansion via DCregs were investigated in vitro through co-culture experiments involving DCregs and either CD4 + CD25 - T-cells or CD4 + CD25 + T-cells. Additionally, an in vivo experiment was conducted using a dextran sulfate sodium (DSS)-induced colitis model in mice. RESULTS: CD103 + CD11b + DC exhibited DCreg-like functionality and was identified as DCreg for subsequent investigation. Analysis of Foxp3 + Treg percentages within a co-culture system of CD4 + CD25 - T-cells and DCregs, with or without FLT3L, demonstrated the involvement of the FLT3/FLT3L axis in driving the differentiation of precursor T-cells into Foxp3 + Tregs induced by DCregs. Cell migration and co-culture assays revealed that the FLT3/FLT3L axis enhanced DCreg migration toward Tregs via the Rho pathway. Additionally, it was observed that DCregs could promote Treg proliferation through the Notch pathway, as inhibition of Notch signaling by DAPT (N-[N-(3,5-difluorophenacetyl)-l-alanyl]-S-phenylglycine t-butyl ester) suppressed Treg expansion within the co-culture system of DCregs and CD4 + T-cells or CD4 + CD25 + T-cells. Furthermore, the FLT3/FLT3L axis influenced JAG1 expression in DCregs, indirectly modulating Treg expansion. In vivo experiments further established that FLT3L promoted DCreg expansion and restored Treg balance in DSS-induced colitis models, thereby ameliorating colitis symptoms in mice. CONCLUSION The FLT3/FLT3L axis is integral to the maintenance of DCreg function in Treg expansion.
Animals ; T-Lymphocytes, Regulatory/immunology* ; Dendritic Cells/immunology* ; Mice ; Mice, Inbred BALB C ; Membrane Proteins/metabolism* ; Receptors, Notch/metabolism* ; Lymphoid Tissue/metabolism* ; Signal Transduction/physiology* ; Coculture Techniques ; Flow Cytometry

BACKGROUND: Immunosuppression is closely related to the pathogenesis of sepsis, but the underlying mechanisms have not yet been fully elucidated. In this study, we aimed to examine the role of the Sterile Alpha Motif, Src Homology 3 domain and nuclear localization signal 1 (SAMSN1) in sepsis and elucidate its potential molecular mechanism in sepsis induced immunosuppression. METHODS: RNA sequencing databases were used to validate SAMSN1 expression in sepsis. The impact of SAMSN1 on sepsis was verified using gene knockout mice. Flow cytometry was employed to delineate how SAMSN1 affects immunity in sepsis, focusing on immune cell types and T cell functions. Clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 (Cas9)-mediated gene editing in RAW264.7 macrophages enabled interrogation of SAMSN1 's regulatory effects on essential macrophage functions, including cell proliferation and phagocytic capacity. The mechanism of SAMSN1 in the interaction between macrophages and T cells was investigated using the RAW264.7 cell line and primary cell lines. RESULTS: SAMSN1 expression was significantly increased in patients with sepsis and was positively correlated with sepsis mortality. Genetic deletion of Samsn1 in murine sepsis model improved T cell survival, elevated T cell cytolytic activity, and activated T cell signaling transduction. Concurrently, Samsn1 knockout augmented macrophage proliferation capacity and phagocytic efficiency. In macrophage, SAMSN1 binds to Kelch-like epichlorohydrin-associated protein 1 (KEAP1), causing nuclear factor erythroid 2-related factor 2 (NRF2) to dissociate from the KEAP1-NRF2 complex and translocate into the nucleus. This promotes the transcription of the coinhibitory molecules CD48/CD86/carcinoembryonic antigen related cell adhesion molecule 1 (CEACAM1), which bind to their corresponding receptors natural killer cell receptor 2B4/CD152/T cell immunoglobulin and mucin domain-containing protein 3 (TIM3) on the surface of T cells, inducing T-cell exhaustion. CONCLUSIONS SAMSN1 deletion augmented adaptive T cell immunity and macrophage phagocytic-proliferative dual function. Furthermore, it mediates the KEAP1-NRF2 axis, which affects the expression of coinhibitory molecules on macrophages, leading to T-cell exhaustion. This novel immunosuppression mechanism potentially provides a candidate molecular target for sepsis immunotherapy.
Animals ; NF-E2-Related Factor 2/metabolism* ; Mice ; Macrophages/immunology* ; Sepsis/metabolism* ; Kelch-Like ECH-Associated Protein 1/genetics* ; T-Lymphocytes/immunology* ; Humans ; Signal Transduction/physiology* ; RAW 264.7 Cells ; Mice, Knockout ; Mice, Inbred C57BL ; Male ; Flow Cytometry ; T-Cell Exhaustion

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

Astragalus membranaceus may be a potential therapy for childhood asthma but its driving mechanism remains elusive. The main components of A. membranaceus were identified by HPLC. The children with asthma remission were divided into two combination group (control group, the combination of budesonide and terbutaline) and A. membranaceus group (treatment group, the combination of budesonide, terbutaline and A. membranaceus). The therapeutic results were compared between two groups after 3-month therapy. Porcine peripheral blood mononuclear cells (PBMCs) were isolated from venous blood by using density gradient centrifugation on percoll. The levels of FoxP3, EGF-β, IL-17 and IL-23 from PBMCs and serum IgE were measured. The relative percentage of Treg/Th17 cells was determined using flow cytometry. The main components of A. membranaceus were calycosin-7-O-glucoside, isoquercitrin, ononin, calycosin, quercetin, genistein, kaempferol, isorhamnetin and formononetin, all of which may contribute to asthma therapy. Lung function was significantly improved in the treatment group when compared with a control group (P < 0.05). The efficacy in preventing the occurrence of childhood asthma was higher in the treatment group than the control group (P < 0.05). The levels of IgE, IL-17 and IL-23 were reduced significantly in the treatment group when compared with the control group, while the levels of FoxP3 and TGF-β were increased in the treatment group when compared with the control group (P < 0.05). A. membranaceus increased the percentage of Treg cells and reduced the percentage of Th17 cells. A. membranaceus is potential natural product for improving the therapeutic efficacy of combination therapy of budesonide and terbutaline for the children with asthma remission by modulating the balance of Treg/Th17 cells.
Animals ; Asthma ; drug therapy ; immunology ; Astragalus propinquus ; chemistry ; Budesonide ; administration & dosage ; Cells, Cultured ; Child ; Child, Preschool ; Cytokines ; metabolism ; Drugs, Chinese Herbal ; administration & dosage ; pharmacology ; Female ; Humans ; Immunologic Factors ; administration & dosage ; pharmacology ; Leukocytes, Mononuclear ; drug effects ; metabolism ; Lung ; drug effects ; physiology ; Male ; Swine ; T-Lymphocytes, Regulatory ; cytology ; drug effects ; Terbutaline ; administration & dosage ; Th17 Cells ; cytology ; drug effects ; Treatment Outcome

OBJECTIVETo study the relationship between the expression of peripheral blood HLA-DR, CD4CD25 regulatory T cells, IL-17 and IL-27 with liver damage in children with human cytomegalovirus (HCMV) infection.

METHODSTwenty-one HCMV children with liver damage and twenty-one HCMV children without liver damage were enrolled in this study. The expression of peripheral blood HLA-DR and CD4CD25 regulatory T cells was detected by flow cytometry. Plasma levels of IL-17 and IL-27 were measured using ELISA.

RESULTSThe plasma levels of IL-17 and IL-27 in children with liver damage were significantly higher than in those without liver damage, while the expression of peripheral blood CD4CD25 regulatory T cells was lower than in those without liver damage (P<0.05). Plasma IL-17 and IL-27 levels were negatively correlated with the expression of peripheral blood CD4CD25 regulatory T cells (P<0.01).

CONCLUSIONSImmune imbalance mediated by CD4CD25 regulatory T cells and over-expression of IL-17 and IL-27 may be involved in the pathogenesis of liver damage in children with HCMV infection.

CD4 Antigens ; immunology ; Cytomegalovirus ; physiology ; Cytomegalovirus Infections ; blood ; complications ; genetics ; Female ; Flow Cytometry ; HLA-DR Antigens ; genetics ; immunology ; Humans ; Infant ; Interleukin-17 ; blood ; genetics ; Interleukin-2 Receptor alpha Subunit ; immunology ; Interleukins ; blood ; genetics ; Liver ; injuries ; metabolism ; Liver Diseases ; blood ; etiology ; immunology ; Male ; T-Lymphocytes, Regulatory ; immunology

T cells are an important adaptive immune response arm that mediates cell-mediated immunity. T cell metabolism plays a central role in T cell activation, proliferation, differentiation, and effector function. Specific metabolic programs are tightly controlled to mediate T cell immune responses, and alterations in T cell metabolism may result in many immunological disorders. In this review, we will summarize the main T cell metabolic pathways and the important factors participating in T cell metabolic programming during T cell homeostasis, differentiation, and function.
Animals ; Cell Physiological Phenomena ; Humans ; Immunity, Cellular ; physiology ; Metabolic Networks and Pathways ; immunology ; T-Lymphocytes ; immunology ; metabolism

T cells efficiently respond to foreign antigens to mediate immune responses against infections but are tolerant to self-tissues. Defect in T cell activation is associated with severe immune deficiencies, whereas aberrant T cell activation contributes to the pathogenesis of diverse autoimmune and inflammatory diseases. An emerging mechanism that regulates T cell activation and tolerance is ubiquitination, a reversible process of protein modification that is counter-regulated by ubiquitinating enzymes and deubiquitinases (DUBs). DUBs are isopeptidases that cleave polyubiquitin chains and remove ubiquitin from target proteins, thereby controlling the magnitude and duration of ubiquitin signaling. It is now well recognized that DUBs are crucial regulators of T cell responses and serve as potential therapeutic targets for manipulating immune responses in the treatment of immunological disorders and cancer. This review will discuss the recent progresses regarding the functions of DUBs in T cells.
Cell Differentiation ; drug effects ; Deubiquitinating Enzymes ; metabolism ; Drug Discovery ; Humans ; Neoplasms ; drug therapy ; pathology ; Signal Transduction ; T-Lymphocytes ; physiology ; Ubiquitination ; drug effects ; physiology

Transforming growth factor (TGF)-β regulates a wide variety of cellular responses, including cell growth arrest, apoptosis, cell differentiation, motility, invasion, extracellular matrix production, tissue fibrosis, angiogenesis, and immune function. Although tumor-suppressive roles of TGF-β have been extensively studied and well-characterized in many cancers, especially at early stages, accumulating evidence has revealed the critical roles of TGF-β as a pro-tumorigenic factor in various types of cancer. This review will focus on recent findings regarding epithelial-mesenchymal transition (EMT) induced by TGF-β, in relation to crosstalk with some other signaling pathways, and the roles of TGF-β in lung and pancreatic cancers, in which TGF-β has been shown to be involved in cancer progression. Recent findings also strongly suggested that targeting TGF-β signaling using specific inhibitors may be useful for the treatment of some cancers. TGF-β plays a pivotal role in the differentiation and function of regulatory T cells (Tregs). TGF-β is produced as latent high molecular weight complexes, and the latent TGF-β complex expressed on the surface of Tregs contains glycoprotein A repetitions predominant (GARP, also known as leucine-rich repeat containing 32 or LRRC32). Inhibition of the TGF-β activities through regulation of the latent TGF-β complex activation will be discussed.
Drug Discovery ; Humans ; Lung Neoplasms ; drug therapy ; immunology ; metabolism ; Membrane Proteins ; metabolism ; Pancreatic Neoplasms ; drug therapy ; immunology ; metabolism ; Signal Transduction ; drug effects ; physiology ; T-Lymphocytes, Regulatory ; metabolism ; Transforming Growth Factor beta ; antagonists & inhibitors ; immunology ; metabolism

BACKGROUNDTriggering receptor expressed on myeloid cell-1 (TREM-1) may play a vital role in mammalian target of rapamycin (mTOR) modulation of CD8+ T-cell differentiation through the transcription factors T-box expressed in T-cells and eomesodermin during the immune response to invasive pulmonary aspergillosis (IPA). This study aimed to investigate whether the mTOR signaling pathway modulates the proliferation and differentiation of CD8+ T-cells during the immune response to IPA and the role TREM-1 plays in this process.

METHODSCyclophosphamide (CTX) was injected intraperitoneally, and Aspergillus fumigatus spore suspension was inoculated intranasally to establish the immunosuppressed IPA mouse model. After inoculation, rapamycin (2 mg.kg-1.d-1) or interleukin (IL)-12 (5 μg/kg every other day) was given for 7 days. The number of CD8+ effector memory T-cells (Tem), expression of interferon (IFN)-γ, mTOR, and ribosomal protein S6 kinase (S6K), and the levels of IL-6, IL-10, galactomannan (GM), and soluble TREM-1 (sTREM-1) were measured.

RESULTSViable A. fumigatus was cultured from the lung tissue of the inoculated mice. Histological examination indicated greater inflammation, hemorrhage, and lung tissue injury in both IPA and CTX + IPA mice groups. The expression of mTOR and S6K was significantly increased in the CTX + IPA + IL-12 group compared with the control, IPA (P = 0.01; P= 0.001), and CTX + IPA (P = 0.034; P= 0.032) groups, but significantly decreased in the CTX + IPA + RAPA group (P < 0.001). Compared with the CTX + IPA group, the proportion of Tem, expression of IFN-γ, and the level of sTREM-1 were significantly higher after IL-12 treatment (P = 0.024, P= 0.032, and P= 0.017, respectively), and the opposite results were observed when the mTOR pathway was blocked by rapamycin (P < 0.001). Compared with the CTX + IPA and CTX + IPA + RAPA groups, IL-12 treatment increased IL-6 and downregulated IL-10 as well as GM, which strengthened the immune response to the IPA infection.

CONCLUSIONSmTOR modulates CD8+ T-cell differentiation during the immune response to IPA. TREM-1 may play a vital role in signal transduction between mTOR and the downstream immune response.

Animals ; CD8-Positive T-Lymphocytes ; cytology ; metabolism ; Cell Differentiation ; genetics ; physiology ; Female ; Interferon-gamma ; metabolism ; Invasive Pulmonary Aspergillosis ; metabolism ; Lymphocyte Activation ; genetics ; physiology ; Mice ; Mice, Inbred BALB C ; Myeloid Cells ; cytology ; metabolism ; Ribosomal Protein S6 Kinases ; metabolism ; TOR Serine-Threonine Kinases ; genetics ; metabolism ; Tissue Culture Techniques

BACKGROUNDAspergillosis infection is common in the patients with insufficient immunity. The role of mammalian target of rapamycin (mTOR), T-box expressed in T-cells (T-bet), and eomesodermin (EOMES) in mediating T lymphocytes differentiation in response to Aspergillus fumigatus infection in immunocompromised rats was investigated in this study.

METHODSInvasive pulmonary aspergillosis (IPA) of immunosuppressive twenty male rats were established and sacrificed at 24 h (n = 5), 48 h (n = 5), 72 h (n = 5), and 96 h (n = 5) after A. fumigatus infection. In addition, control (n = 5), cyclophosphamide (CTX) (n = 5), and aspergillosis (n = 5) group were also established the tissues and pathology of lung tissue was examined by hematoxylin and eosin staining. CD8+ T-cells was sorted by flow cytometry. Serum mTOR, S6K, T-bet, and EOMES were quantified by enzyme-linked immunosorbent assay.

RESULTSHistology of lung tissue indicated severe lung tissue injury including infiltration of inflammatory cells, alveolar wall damage or degradation, blood congestion, and hemorrhage in the CTX, IPA, and CTX + IPA rats. Hyphae were seen in the IPA, and CTX + IPA groups. The proportion of CD8+ T-cells was significantly increased in the animals of CTX + IPA. Memory CD8+ T-cells was significantly increased in early stage (24 h and 48 h, P < 0.001), but decreased in the late phase of fungal infection (72 h and 96 h) in the animals of CTX + IPA. In addition, at early stage of fungal infection (24 h and 48 h), serum mTOR (P < 0.001), S6K (P < 0.001), and T-bet (P < 0.05) was significantly higher, while EOMES was significantly lower (P < 0.001), in CTX + IPA group than that in control, CTX alone or IPA alone group. Conversely, serum mTOR, S6K, T-bet, and EOMES showed opposite changed in the late stage (72 h and 96 h). Pearson's correlation analysis indicated that mTOR and S6K were significantly correlated with T-bet (r = 0.901 and 0.91, respectively, P < 0.001), but negatively and significantly correlated with EOMES (r = -0.758 and -0.751, respectively, P < 0.001).

CONCLUSIONSmTOR may regulate transcription factors of EOMES and T-bet, and by which mechanism, it may modulate lymphocytes differentiation in animals with immune suppression and fungal infection.

Animals ; CD8-Positive T-Lymphocytes ; cytology ; metabolism ; Cell Differentiation ; genetics ; physiology ; Invasive Pulmonary Aspergillosis ; metabolism ; pathology ; Lung ; metabolism ; pathology ; Lymphocytes ; cytology ; immunology ; Male ; Rats ; Rats, Wistar ; T-Box Domain Proteins ; genetics ; metabolism ; TOR Serine-Threonine Kinases ; genetics ; metabolism ; Tissue Culture Techniques