Mycobacterium tuberculosis(Mtb)employs multiple mechanisms,such as phagocytosis and autophagy,to evade innate immune clearance and establish infection.In the present study,we identified the ESX-1 secretion-associated ...Mycobacterium tuberculosis(Mtb)employs multiple mechanisms,such as phagocytosis and autophagy,to evade innate immune clearance and establish infection.In the present study,we identified the ESX-1 secretion-associated protein EspL,which promotes Mtb survival by inhibiting phagosome maturation and autophagy initiation.EspL knockout decreased Mtb intracellular survival,while EspL overexpression increased bacterial survival by interfering with phagocytosis and autophagy.EspL interacts with ULK1 and promotes its phosphorylation at Ser^(757),leading to the inhibition of autophagy initiation.Additionally,overexpression of EspL reduced antigen presentation and T-cell responses both in vitro and in vivo.Our findings revealed that EspL interferes with autophagy and antigen presenta-tion by suppressing ULK1 activation.These insights provide a novel understanding of Mtb pathogenicity.展开更多
Alcoholic patients have a high incidence of hepatitis C virus （HCV） infection. Alcohol consumption enhances the severity of the HCV disease course and worsens the outcome of chronic hepatitis C. The accumulation of ...Alcoholic patients have a high incidence of hepatitis C virus （HCV） infection. Alcohol consumption enhances the severity of the HCV disease course and worsens the outcome of chronic hepatitis C. The accumulation of virally infected cells in the liver is related to the HCV- induced inability of the immune system to recognize infected cells and to develop the immune responses. This review covers the effects of HCV proteins and ethanol on major histocompatibility complex （MHC） class Ⅰ- and class Ⅱ-restricted antigen presentation. Here, we discuss the liver which functions as an immune privilege organ; factors, which affect cleavage and loading of antigenic peptides onto MHC class I and class ~I in hepatocytes and dendritic cells, and the modulating effects of ethanol and HCV on antigen presentation by liver cells. Altered antigen presentation in the liver limits the ability ＇of the immune system to clear HCV and infected cells and contributes to disease progression. HCV by itself affects dendritic cell function, switching their cytokine profile to the suppressive phenotype of interleukin-10 （IL-10） and transforming growth factor beta （TGFβ） predominance, preventing cell maturation and allostimulation capacity. The synergistic action of ethanol with HCV results in the suppression of MHC class Ⅱ-restricted antigen presentation. In addition, ethanol metabolism and HCV proteins reduce proteasome function and interferon signaling, thereby suppressing the generation of peptides for MHC class I -restricted antigen presentation. Collectively, ethanol exposure further impairs antigen presentation in HCV-infected liver cells, which may provide a partial explanation for exacerbations and the poor outcome of HCV infection in alcoholics.展开更多
Systemic lupus erythematosus （SLE） is a typical autoimmune disease involving multiple systems and organs. Ample evidence suggests that autoreactive T cells play a pivotal role in the development of this autoimmune d...Systemic lupus erythematosus （SLE） is a typical autoimmune disease involving multiple systems and organs. Ample evidence suggests that autoreactive T cells play a pivotal role in the development of this autoimmune disorder. This study was undertaken to investigate the mechanisms of interaction between antigen presenting cells （APCs） and an autoreactive T cell （ATLI） clone obtained from lupus-prone BXSB mice. ATLI cells, either before or after 7-ray irradiation, were able to activate naive B cells, as determined by B cell proliferation assays. Macrophages from BXSB mice were able to stimulate the proliferation of resting ATL 1 cells at a responder/stimulator （R/S） ratio of 1/2.5. Dendritic cells （DCs） were much more powerful stimulators for ATLI cells on a per cell basis. The T cell stimulating ability ofmacrophages and B cells, but not DCs, was sensitive to T-ray irradiation. Monoclonal antibodies against mouse MHC-Ⅱ and CD4 were able to block DC-mediated stimulation of ATL 1 proliferation, indicating cognate recognition between ATL 1 and APCs. Our data suggest that positive feedback loops involving macrophages, B cells and autoreactive T cells may play a pivotal role in keeping the momentum of autoimmune responses leading to autoimmune diseases.展开更多
Background Cilostazol, an anti-platelet drug for treating coronary heart disease, has been reported to modulate immune cell functions Plasmacytoid dendritic cells （pDCs） have been found to participate in the progres...Background Cilostazol, an anti-platelet drug for treating coronary heart disease, has been reported to modulate immune cell functions Plasmacytoid dendritic cells （pDCs） have been found to participate in the progression of atherosclerosis mainly through interferon ct （IFN-ct） production. Whether cilostazol influences pDCs activation is still not clear. In this study, we aimed to investigate the effects of cilostazol on cell activation and antigen presentation ofpDCs in vitro in this study. Methods Peripheral blood mononuclear cells isolated by Ficoll cen- trifugation and pDCs sorted by flow cytometry were used in this study. After pretreated with cilostazol for 2 h, cells were stimulated with CpG-A, R848 or virus for 6 h or 20 h, or stimulated with CpG-B for 48 h and then co-cultured with naive T cell for five days. Cytokines in supernatant and intracellular cytokines were analyzed by ELISA or flow cytometry respectively. Results Our data indicated that cilostazol could inhibit IFN-α and tumor necrosis factor α （TNF-α） production from pDCs in a dose-dependent manner. In addition, the ability of priming na ve T cells of pDCs was also impaired by cilostazol. The inhibitory effect was not due to cell killing since the viability of pDCs did not change upon cilostazol treatment. Conclusion Cilostazol inhibits pDCs cell activation and antigen presentation in vitro, which may explain how cilostazol protects against atherosclerosis.展开更多
Porcine reproductive and respiratory syndrome(PRRS) is one of the most important diseases of swine industry. The causal agent, PRRS-virus(PRRSV), is able to evade the host immune response and survive in the organism c...Porcine reproductive and respiratory syndrome(PRRS) is one of the most important diseases of swine industry. The causal agent, PRRS-virus(PRRSV), is able to evade the host immune response and survive in the organism causing transient infections. Despite all scientific efforts, there are still some gaps in the knowledge of the pathogenesis of this disease. Antigen presenting cells(APCs), as initiators of the immune response, are located in the first line of defense against microorganisms, and are responsible for antigen recognition, processing and presentation. Dendritic cells(DCs) are the main type of APC involved in antigen presentation and they are susceptible to PRRSV infection. Thus, PRRSV replication in DCs may trigger off different mechanisms to impair the onset of a host effective immune response against the virus. On the one side, PRRSV may impair the basic functions of DCs by regulating the expression of major histocompatibility complex class Ⅱ and CD80/86. Other strategy followed by the virus is the induction of cell death of APCs by apoptosis, necrosis or both of them. The impairment and/or cell death ofAPCs could lead to a failure in the onset of an efficient immune response, as long as cells could not properly activate T cells. Future aspects to take into account are also discussed in this review.展开更多
Traditionally,macroautophagy(autophagy)is viewed as a pathway of cell survival.Autophagy ensures the elimination of damaged or unwanted cytosolic components and provides a source of cellular nutrients during periods o...Traditionally,macroautophagy(autophagy)is viewed as a pathway of cell survival.Autophagy ensures the elimination of damaged or unwanted cytosolic components and provides a source of cellular nutrients during periods of stress.Interestingly,autophagy can also directly intersect with,and impact,other major pathways of cellular function.Here,we will review the contribution of autophagy to pathways of antigen presentation.The autophagy machinery acts to modulate both MHCⅠ and MHCⅡ antigen presentation.As such autophagy is an important participant in pathways that elicit host cell immunity and the elimination of infectious pathogens.展开更多
The intestinal immune system maintains a delicate balance between immunogenicity against invading pathogens and tolerance of the commensal microbiota. Inflammatory bowel disease (IBD) involves a breakdown in tolerance...The intestinal immune system maintains a delicate balance between immunogenicity against invading pathogens and tolerance of the commensal microbiota. Inflammatory bowel disease (IBD) involves a breakdown in tolerance towards the microbiota. Dendritic cells (DC), macrophages (MΦ) and B-cells are known as professional antigen-presenting cells (APC) due to their specialization in presenting processed antigen to T-cells, and in turn shaping types of T-cell responses generated. Intestinal DC are migratory cells, unique in their ability to generate primary T-cell responses in mesenteric lymph nodes or Peyer’s patches, whilst MΦ and B-cells contribute to polarization and differentiation of secondary T-cell responses in the gut lamina propria. The antigen-sampling function of gut DC and MΦ enables them to sample bacterial antigens from the gut lumen to determine types of T-cell responses generated. The primary function of intestinal B-cells involves their secretion of large amounts of immunoglobulin A, which in turn contributes to epithelial barrier function and limits immune responses towards to microbiota. Here, we review the role of all three types of APC in intestinal immunity, both in the steady state and in inflammation, and how these cells interact with one another, as well as with the intestinal microenvironment, to shape mucosal immune responses. We describe mechanisms of maintaining intestinal immune tolerance in the steady state but also inappropriate responses of APC to components of the gut microbiota that contribute to pathology in IBD.展开更多
AIM:To investigate the anti-inflammatory effects of cinnamon extract and elucidate its mechanisms for targeting the function of antigen presenting cells.METHODS:Cinnamon extract was used to treat murine macrophage cel...AIM:To investigate the anti-inflammatory effects of cinnamon extract and elucidate its mechanisms for targeting the function of antigen presenting cells.METHODS:Cinnamon extract was used to treat murine macrophage cell line(Raw 264.7),mouse primary antigen-presenting cells(APCs,MHCII+) and CD11c+dendritic cells to analyze the effects of cinnamon extract on APC function.The mechanisms of action of cinnamon extract on APCs were investigated by analyzing cytokine production,and expression of MHC antigens and co-stimulatory molecules by quantitative real-time PCR and flow cytometry.In addition,the effect of cinnamon extract on antigen presentation capacity and APC-dependent T-cell differentiation were analyzed by [H3]-thymidine incorporation and cytokine analysis,respectively.To confirm the anti-inflammatory effects of cinnamon extract in vivo,cinnamon or PBS was orally administered to mice for 20 d followed by induction of experimental colitis with 2,4,6 trinitrobenzenesulfonic acid.The protective effects of cinnamon extract against experimental colitis were measured by checking clinical symptoms,histological analysis and cytokine expression prof iles in inflamed tissue.RESULTS:Treatment with cinnamon extract inhibited maturation of MHCII+ APCs or CD11c+ dendritic cells(DCs) by suppressing expression of co-stimulatory molecules(B7.1,B7.2,ICOS-L),MHCII and cyclooxygenase(COX)-2.Cinnamon extract induced regulatory DCs(rDCs) that produce low levels of pro-inflammatory cytokines [interleukin(IL)-1β,IL-6,IL-12,interferon(IFN)-γ and tumor necrosis factor(TNF)-α] while expressing high levels of immunoregulatory cytokines(IL-10 and transforming growth factor-β).In addition,rDCs generated by cinnamon extract inhibited APC-dependent T-cell proliferation,and converted CD4+ T cells into IL-10high CD4+ T cells.Furthermore,oral administration of cinnamon extract inhibited development and progression of intestinal colitis by inhibiting expression of COX-2 and pro-inflammatory cytokines(IL-1β,IFN-γ and TNF-α),while enhancing IL-10 levels.CONCLUSION:Our study suggests the potential of cinnamon extract as an anti-inflammatory agent by targeting the generation of regulatory APCs and IL-10+ regulatory T cells.展开更多
Presentation of antigenic peptide to T cells by major histocompatibility complex (MHC) class I molecules is the key to the cellular immune response.Non-self intracellular proteins are processed into short peptides and...Presentation of antigenic peptide to T cells by major histocompatibility complex (MHC) class I molecules is the key to the cellular immune response.Non-self intracellular proteins are processed into short peptides and transported into endoplasmic reticulum (ER) where they are assembled with class I molecules assisted by several chaperone proteins to form trimeric complex.MHC class I complex loaded with optimised peptides travels to the cell surface of antigen presentation cells to be recognised by T cells.The cells presenting non-self peptides are cleared by CD8 positive T cells.In order to ensure that T cells detect an infection or mutation within the target cells the process of peptide loading and class I expression must be carefully regulated.Many of the cellular components involved in antigen processing and class I presentation are known and their various functions are now becoming clearer.Cellular & Molecular Immunology.2004;1(1):22-30.展开更多
The liver is an important immunological organ that controls systemic tolerance.The liver harbors professional and unconventional antigen-presenting cells that are crucial for tolerance induction and maintenance.Orches...The liver is an important immunological organ that controls systemic tolerance.The liver harbors professional and unconventional antigen-presenting cells that are crucial for tolerance induction and maintenance.Orchestrating the immune response in homeostasis depends on a healthy and well-toned immunological liver microenvironment,which Is maintained by the crosstalk of liver-resident antigen-presenting cells and intrahepatic and liver-infiltrating leukocytes.In response to pathogens or autoantigens,tolerance is disrupted by unknown mechanisms.Intrahepatic parenchymal and nonparenchymal cells exhibit unique antigen-presenting properties.The presentation of microbial and endogenous lipid-,metabolite-and peptide-derived antigens from the gut via conventional and nonconventional mechanisms can educate intrahepatic immune cells and elicit effector responses or tolerance.Perturbation of this balance results in autoimmune liver diseases,such as autoimmune hepatitis,primary biliary cholangitis,and primary sclerosing cholangitis.Although the exact etiologies of these autoimmune liver diseases are unknown,it is thought that the disruption of tolerance towards self-antigens and microbial metabolites and lipids,as well as alterations in bile acid composition,may result in changes in effector cell activation and polarization and may reduce or impair protective antiinflammatory regulatory T and B cell responses.Additionally,the canonical and noncanonical transmission of antigens and antigen:MHC complexes via trogocytosis or extracellular vesicles between different(non)immune cells in the liver may play a role in the induction of hepatic inflammation and tolerance.Here,we summarize emerging aspects of antigen presentation,autoantibody production,and the application of novel therapeutic approaches in the characterization and treatment of autoimmune liver diseases.展开更多
[Objective] This study aimed to investigate the changes of the transcriptional levels of molecules associated with endogenous antigen processing and presenta- tion in porcine skin-derived dendritic cells infected with...[Objective] This study aimed to investigate the changes of the transcriptional levels of molecules associated with endogenous antigen processing and presenta- tion in porcine skin-derived dendritic cells infected with PCV2 in vivo. [Method] Healthy 40-day-old Landrace piglets were infected with porcine circovirus type 2 （PCV2） and euthanized on the 34, 7rd, 14th, 21st and 35th d post inoculation （DPI）. The porcine skin-derived dendritic cells （DCs） were collected to analyze the transcrip- tional levels of molecules （LMP7, UBP, MHC-I, calreticulin） associated with endogenous antigen processing and presentation by using real-time fluorescent quantitative PCR （real-time FQ-PCR）. [Result] The results showed that the level of LMP7 mR- NAs was reduced significantly on the 3DPI （P〈0.05）; the level of UBP mRNAs was consistently up-regulated, which increased significantly on the 21DPI and 35DPI （P〈 0.05）; the level of MHC-I mRNAs was significantly down-regulated on the 7DPI （P〈 0.05）; the level of calreticulin mRNAs was up-regulated slightly without significant dif- ference. [Conclusion] PCV2 can inhibit the endogenous antigen processing and presentation ability of porcine skin-derived DCs at early stages of infection.展开更多
Adoptive cell therapy(ACT)is an immunotherapy strategy for cancer that has seen widespread clinical success.During ACT,patient-derived lymphocytes are stimulated with the antigen of interest ex vivo,proliferated,then ...Adoptive cell therapy(ACT)is an immunotherapy strategy for cancer that has seen widespread clinical success.During ACT,patient-derived lymphocytes are stimulated with the antigen of interest ex vivo,proliferated,then returned to the patient to initiate an antigen-specific antitumor response.While effective,this process is resource-intensive and logistically impossible for many patients.Particulate artificial antigen presenting cells(aAPCs)offer a potential“off-the-shelf”alternative to ex vivo ACT.While particulate aAPCs perform well in vitro,they have had limited success in vivo due to poor bioavailability after injection.Barriers to bioavailability include rapid clearance,unfavorable biodistribution,and inadequate interactions with CD8+T cells at sites of interest.Biomaterial properties such as elasticity have been shown to vastly impact the bioavailability and particle-cell interactions,but this has yet to be investigated in the context of aAPCs for in vivo T-cell stimulation.Previous literature likewise indicates that biomaterial properties,especially elasticity,can modulate T-cell activation in vitro.With the goal of creating a more biomimetic,next-generation particulate aAPC,we developed a poly(ethylene)glycol hydrogel particle platform with tunable elasticity to investigate the impact of elasticity on antigen-specific T cell activation for in vivo adoptive transfer.Using this knowledge,we were able to gain more precise control over in vivo T cell activation and investigate possible mechanisms including the effects of aAPC elasticity on T cell binding,macrophage uptake,and the protein corona.展开更多
The intestinal immune system maintains tolerance to harmless food proteins and gut microbiota through peripherally derived RORγt+Tregs(pTregs),which prevent food intolerance and inflammatory bowel disease.Recent stud...The intestinal immune system maintains tolerance to harmless food proteins and gut microbiota through peripherally derived RORγt+Tregs(pTregs),which prevent food intolerance and inflammatory bowel disease.Recent studies suggested that RORγt+antigen-presenting cells(APCs),which encompass rare dendritic cell(DC)subsets and type 3 innate lymphoid cells(ILC3s),are key to pTreg induction.Here,we developed a mouse with reduced RORγt+APCs by deleting a specific cis-regulatory element of Rorc encoding RORγt.Single-cell RNA sequencing and flow cytometry analyses confirmed the depletion of a RORγt+DC subset and ILC3s.These mice showed a secondary reduction in pTregs,impaired tolerance to oral antigens,and an increase in T helper(Th)2 cells.Conversely,ILC3-deficient mice showed no pTregs or Th2 cell abnormalities.Lineage tracing revealed that RORγt+DCs share a lymphoid origin with ILC3s,consistent with their similar phenotypic traits.These findings highlight the role of lymphoid RORγt+DCs in maintaining intestinal immune balance and preventing conditions like food allergies.展开更多
Background Antigen loaded eosinophils (EOSs) instilled intratracheally into mice were capable of inducing Th2 type cytokine production in the draining lymph nodes The aim of the present study was to evaluate whet...Background Antigen loaded eosinophils (EOSs) instilled intratracheally into mice were capable of inducing Th2 type cytokine production in the draining lymph nodes The aim of the present study was to evaluate whether EOSs within the tracheobronchial lumen can stimulate Th2 cell expansion in the lung tissues Methods Airway EOSs were recovered from ovalbumin sensitized and challenged BALB/c mice, these EOSs were then cocultured with CD4 + cells isolated from sensitized mice in the absence or presence of anti CD80 or/and CD86 monoclonal antibodies Airway EOSs were instilled into the trachea of sensitized mice. At the day 3 thereafter, the lung tissues were removed and prepared into cell suspensions for culture Cell free culture supernatants were collected for detection of cytokines Results Airway EOSs functioned as CD80 and CD86 dependent antigen presenting cells to stimulate lung CD4 + lymphocytes to produce interleukin 4, interleukin 5 and interleukin 13, but not interferon γ in in vitro assay When instilled intratracheally in sensitized recipient mice, airway EOSs primed lung Th2 cells in vivo for interleukin 4, interleukin 5 and interleukin 13, but not interferon γ, production during the in vitro culture that was also CD80 and CD86 dependent Conclusion EOSs within the lumina of airways could process inhaled antigen and function in vitro and in vivo as antigen presenting cells to promote expansion of Th2 cells in the lungs展开更多
Administered in vivo, covalent receptor-recognized α2-macroglobulin (α2M*)-antigen complexes enhance humoral and cell-mediated immunity. We hypothesized that in vivo α2M*-encapsulation could be promoted in the sett...Administered in vivo, covalent receptor-recognized α2-macroglobulin (α2M*)-antigen complexes enhance humoral and cell-mediated immunity. We hypothesized that in vivo α2M*-encapsulation could be promoted in the setting of vaccines that co-deliver α2M* with unbound antigen, thereby eliminating the need to prepare complexes in vitro. Mice immunized intradermally with co-delivered α2M* and OVA demonstrated antigen-specific immune responses, including anti-tumor responses, similar to those elicited by conjugated α2M*-OVA complexes. Enhanced immunity appears to result from in vivo α2M*-encapsulation of antigen. This finding represents a significant advancement in the development of α2M* as an antigen delivery vehicle capable of enhancing the presentation of subunit vaccines.展开更多
Innate immunity in fish is critically important for preventing the entry of pathogenic microorganisms by adeptly recognizing pathogen-associated molecular patterns(PAMPs)through pattern recognition receptors(PRRs).Con...Innate immunity in fish is critically important for preventing the entry of pathogenic microorganisms by adeptly recognizing pathogen-associated molecular patterns(PAMPs)through pattern recognition receptors(PRRs).Concurrently,the adaptive immune response equips the vertebrate immune system to identify and retain memory of specific pathogens,thereby facilitating enhanced secondary responses upon re-exposure.Antigen-presenting cells(APCs)are integral to this process,as they recognize antigens via mechanisms including PRRs,internalize them,and process these antigens for presentation to T cells.This interaction triggers the activation of both T cells and B cells,initiating a robust priming of the adaptive immune system and establishing a functional bridge between innate and adaptive immunity.Antigen presentation serves as a pivotal mechanism for T cell activation and B cell differentiation,thereby leading to the establishment of effective antimicrobial protection.Vaccination of fish is of paramount importance for preventing specific infectious diseases and is economically and environmentally essential for the development of a sustainable fish aquaculture industry.The design of efficacious vaccines necessitates the establishment of long-term protection against specific antigenic challenges,with APCs occupying a central role in this endeavor.This review summarizes the most recent studies on fish antigen presentation pathways and elucidates the mechanisms involved in the recognition,processing,and presentation of antigens by APCs,triggering activation of T cells.Moreover,this review highlights recent findings concerning immune regulatory factors that activate adaptive immunity,including adjuvants and immunostimulants,providing the prospects for fish vaccine applications.A comprehensive understanding of how fish APCs detect and respond to antigens will have profound implications for the future development of tailored vaccination strategies and the rational design of interventions against infectious diseases impacting the commercial aquaculture sector.展开更多
An immunostimulatory factor was identified to be secreted by antigen-pulsed maorophages. This factor was able to induce the generation of antigen specific T helper lymphocytes in vitro as well as in vivo. Further in v...An immunostimulatory factor was identified to be secreted by antigen-pulsed maorophages. This factor was able to induce the generation of antigen specific T helper lymphocytes in vitro as well as in vivo. Further in vitro experiments testing for the genetic restriction of this factor indicated that it is a genetically-restricted antigen specific factor (ASF). The Cunningham plaque assay was used to quantify the generation of T helper lymphocytes by measuring the number of plaque forming cells after sequential incubations of antigen-pulsed maorophages with T lymphocytes, and then spleen cells, and finally the TNP-coated sheep red blood cells.展开更多
Human endoplasmic reticulum aminopeptidase 1 (ERAP1) is one of two ER luminal aminopeptidases that participate in the final processing of peptide precursors and generates the N-termini of the MHC class I-restricted ep...Human endoplasmic reticulum aminopeptidase 1 (ERAP1) is one of two ER luminal aminopeptidases that participate in the final processing of peptide precursors and generates the N-termini of the MHC class I-restricted epitopes. In order to investigate the interactions of its binding site with substrate peptides, X-ray crystallographic analyses have been carried out to study structures of ERAP1 regulatory (ERAP1_R) domain in complex with antigenic peptides. Single-chain bimodular constructs with various antigenic peptides linked to the C-terminal end of ERAP1_R domain are designed to facilitate crystallization process of these complexes. These recombinant proteins have been purified and crystalized, and x-ray diffraction data of one crystal have been processed to a resolution of 2.8 . The crystal belongs to the space group P21, with unit cell parameters a =64.2, b = 66.8, c = 66.3 , β = 110.2°. A Refmac-refined omit map reveals a clear density for the antigenic peptide’s carboxylate-end that is in contact with the ERAP1 regulatory domain of neighboring molecule. Thus the single-chain bimodular constructs have provided an expedited approach to study sequence-specific interactions between the ERAP1 regulatory domain and antigen peptide’s C-terminal ends.展开更多
Immunization has long played essential roles in preventing diseases.However,the desire for precision delivery of vaccines to boost a robust immune response remains largely unmet.Here,we describe the use of acupoint de...Immunization has long played essential roles in preventing diseases.However,the desire for precision delivery of vaccines to boost a robust immune response remains largely unmet.Here,we describe the use of acupoint delivery of nanovaccines(ADN)to elicit dual-niche immunological priming.ADN can simultaneously stimulate mast cell-assisted maturation of dendritic cells at the acupoint and enable direct delivery of nanovaccines into the draining lymph nodes.We demonstrate that ADN not only provokes antigen presentation by lymph node-resident CD8α^(+)dendritic cells,but also induces the accumulation of nanovaccines in B-cell zones,amplifying antigen-specific cytotoxic T lymphocyte responses and immunoglobulin G antibody expression in draining lymph nodes.ADN also generates systemic immune responses by causing immune memory and preventing T-cell anergy in the spleen.Further supported by evoking effective antitumor responses and high-level antiviral antibodies in mice,ADN provides a simple yet versatile platform for advanced nanovaccination.展开更多
基金supported by the National Natural Science Foundation of China under grant number U21A20259the National Key Research and Development Program of China under grant number 2021YFD1800401.
文摘Mycobacterium tuberculosis(Mtb)employs multiple mechanisms,such as phagocytosis and autophagy,to evade innate immune clearance and establish infection.In the present study,we identified the ESX-1 secretion-associated protein EspL,which promotes Mtb survival by inhibiting phagosome maturation and autophagy initiation.EspL knockout decreased Mtb intracellular survival,while EspL overexpression increased bacterial survival by interfering with phagocytosis and autophagy.EspL interacts with ULK1 and promotes its phosphorylation at Ser^(757),leading to the inhibition of autophagy initiation.Additionally,overexpression of EspL reduced antigen presentation and T-cell responses both in vitro and in vivo.Our findings revealed that EspL interferes with autophagy and antigen presenta-tion by suppressing ULK1 activation.These insights provide a novel understanding of Mtb pathogenicity.
基金Supported by Development funds from Section of Gastroenterology/Hepatology, Internal Medicine, University of Nebraska Medical Center
文摘Alcoholic patients have a high incidence of hepatitis C virus （HCV） infection. Alcohol consumption enhances the severity of the HCV disease course and worsens the outcome of chronic hepatitis C. The accumulation of virally infected cells in the liver is related to the HCV- induced inability of the immune system to recognize infected cells and to develop the immune responses. This review covers the effects of HCV proteins and ethanol on major histocompatibility complex （MHC） class Ⅰ- and class Ⅱ-restricted antigen presentation. Here, we discuss the liver which functions as an immune privilege organ; factors, which affect cleavage and loading of antigenic peptides onto MHC class I and class ~I in hepatocytes and dendritic cells, and the modulating effects of ethanol and HCV on antigen presentation by liver cells. Altered antigen presentation in the liver limits the ability ＇of the immune system to clear HCV and infected cells and contributes to disease progression. HCV by itself affects dendritic cell function, switching their cytokine profile to the suppressive phenotype of interleukin-10 （IL-10） and transforming growth factor beta （TGFβ） predominance, preventing cell maturation and allostimulation capacity. The synergistic action of ethanol with HCV results in the suppression of MHC class Ⅱ-restricted antigen presentation. In addition, ethanol metabolism and HCV proteins reduce proteasome function and interferon signaling, thereby suppressing the generation of peptides for MHC class I -restricted antigen presentation. Collectively, ethanol exposure further impairs antigen presentation in HCV-infected liver cells, which may provide a partial explanation for exacerbations and the poor outcome of HCV infection in alcoholics.
基金supported by grants from the National Key Basic Research Programs(2001CB510007)National Natural Science Foundation of China(30371303).
文摘Systemic lupus erythematosus （SLE） is a typical autoimmune disease involving multiple systems and organs. Ample evidence suggests that autoreactive T cells play a pivotal role in the development of this autoimmune disorder. This study was undertaken to investigate the mechanisms of interaction between antigen presenting cells （APCs） and an autoreactive T cell （ATLI） clone obtained from lupus-prone BXSB mice. ATLI cells, either before or after 7-ray irradiation, were able to activate naive B cells, as determined by B cell proliferation assays. Macrophages from BXSB mice were able to stimulate the proliferation of resting ATL 1 cells at a responder/stimulator （R/S） ratio of 1/2.5. Dendritic cells （DCs） were much more powerful stimulators for ATLI cells on a per cell basis. The T cell stimulating ability ofmacrophages and B cells, but not DCs, was sensitive to T-ray irradiation. Monoclonal antibodies against mouse MHC-Ⅱ and CD4 were able to block DC-mediated stimulation of ATL 1 proliferation, indicating cognate recognition between ATL 1 and APCs. Our data suggest that positive feedback loops involving macrophages, B cells and autoreactive T cells may play a pivotal role in keeping the momentum of autoimmune responses leading to autoimmune diseases.
文摘Background Cilostazol, an anti-platelet drug for treating coronary heart disease, has been reported to modulate immune cell functions Plasmacytoid dendritic cells （pDCs） have been found to participate in the progression of atherosclerosis mainly through interferon ct （IFN-ct） production. Whether cilostazol influences pDCs activation is still not clear. In this study, we aimed to investigate the effects of cilostazol on cell activation and antigen presentation ofpDCs in vitro in this study. Methods Peripheral blood mononuclear cells isolated by Ficoll cen- trifugation and pDCs sorted by flow cytometry were used in this study. After pretreated with cilostazol for 2 h, cells were stimulated with CpG-A, R848 or virus for 6 h or 20 h, or stimulated with CpG-B for 48 h and then co-cultured with naive T cell for five days. Cytokines in supernatant and intracellular cytokines were analyzed by ELISA or flow cytometry respectively. Results Our data indicated that cilostazol could inhibit IFN-α and tumor necrosis factor α （TNF-α） production from pDCs in a dose-dependent manner. In addition, the ability of priming na ve T cells of pDCs was also impaired by cilostazol. The inhibitory effect was not due to cell killing since the viability of pDCs did not change upon cilostazol treatment. Conclusion Cilostazol inhibits pDCs cell activation and antigen presentation in vitro, which may explain how cilostazol protects against atherosclerosis.
基金Supported by The Spanish Ministry of Education and Science,No.AGL2009-12438/GAN
文摘Porcine reproductive and respiratory syndrome(PRRS) is one of the most important diseases of swine industry. The causal agent, PRRS-virus(PRRSV), is able to evade the host immune response and survive in the organism causing transient infections. Despite all scientific efforts, there are still some gaps in the knowledge of the pathogenesis of this disease. Antigen presenting cells(APCs), as initiators of the immune response, are located in the first line of defense against microorganisms, and are responsible for antigen recognition, processing and presentation. Dendritic cells(DCs) are the main type of APC involved in antigen presentation and they are susceptible to PRRSV infection. Thus, PRRSV replication in DCs may trigger off different mechanisms to impair the onset of a host effective immune response against the virus. On the one side, PRRSV may impair the basic functions of DCs by regulating the expression of major histocompatibility complex class Ⅱ and CD80/86. Other strategy followed by the virus is the induction of cell death of APCs by apoptosis, necrosis or both of them. The impairment and/or cell death ofAPCs could lead to a failure in the onset of an efficient immune response, as long as cells could not properly activate T cells. Future aspects to take into account are also discussed in this review.
基金supported by a National Health and Medical Research Council of Australia Career Development Award.
文摘Traditionally,macroautophagy(autophagy)is viewed as a pathway of cell survival.Autophagy ensures the elimination of damaged or unwanted cytosolic components and provides a source of cellular nutrients during periods of stress.Interestingly,autophagy can also directly intersect with,and impact,other major pathways of cellular function.Here,we will review the contribution of autophagy to pathways of antigen presentation.The autophagy machinery acts to modulate both MHCⅠ and MHCⅡ antigen presentation.As such autophagy is an important participant in pathways that elicit host cell immunity and the elimination of infectious pathogens.
文摘The intestinal immune system maintains a delicate balance between immunogenicity against invading pathogens and tolerance of the commensal microbiota. Inflammatory bowel disease (IBD) involves a breakdown in tolerance towards the microbiota. Dendritic cells (DC), macrophages (MΦ) and B-cells are known as professional antigen-presenting cells (APC) due to their specialization in presenting processed antigen to T-cells, and in turn shaping types of T-cell responses generated. Intestinal DC are migratory cells, unique in their ability to generate primary T-cell responses in mesenteric lymph nodes or Peyer’s patches, whilst MΦ and B-cells contribute to polarization and differentiation of secondary T-cell responses in the gut lamina propria. The antigen-sampling function of gut DC and MΦ enables them to sample bacterial antigens from the gut lumen to determine types of T-cell responses generated. The primary function of intestinal B-cells involves their secretion of large amounts of immunoglobulin A, which in turn contributes to epithelial barrier function and limits immune responses towards to microbiota. Here, we review the role of all three types of APC in intestinal immunity, both in the steady state and in inflammation, and how these cells interact with one another, as well as with the intestinal microenvironment, to shape mucosal immune responses. We describe mechanisms of maintaining intestinal immune tolerance in the steady state but also inappropriate responses of APC to components of the gut microbiota that contribute to pathology in IBD.
基金Supported by Grants from the BioGreen 21 Program, Rural Development Administration (PJ007054)Regional Technology Innovation Program of the MOCIE (RTI05-01-01)Korea Healthcare Technology R&D Project, Ministry of Health and Welfare (A080588-20)
文摘AIM:To investigate the anti-inflammatory effects of cinnamon extract and elucidate its mechanisms for targeting the function of antigen presenting cells.METHODS:Cinnamon extract was used to treat murine macrophage cell line(Raw 264.7),mouse primary antigen-presenting cells(APCs,MHCII+) and CD11c+dendritic cells to analyze the effects of cinnamon extract on APC function.The mechanisms of action of cinnamon extract on APCs were investigated by analyzing cytokine production,and expression of MHC antigens and co-stimulatory molecules by quantitative real-time PCR and flow cytometry.In addition,the effect of cinnamon extract on antigen presentation capacity and APC-dependent T-cell differentiation were analyzed by [H3]-thymidine incorporation and cytokine analysis,respectively.To confirm the anti-inflammatory effects of cinnamon extract in vivo,cinnamon or PBS was orally administered to mice for 20 d followed by induction of experimental colitis with 2,4,6 trinitrobenzenesulfonic acid.The protective effects of cinnamon extract against experimental colitis were measured by checking clinical symptoms,histological analysis and cytokine expression prof iles in inflamed tissue.RESULTS:Treatment with cinnamon extract inhibited maturation of MHCII+ APCs or CD11c+ dendritic cells(DCs) by suppressing expression of co-stimulatory molecules(B7.1,B7.2,ICOS-L),MHCII and cyclooxygenase(COX)-2.Cinnamon extract induced regulatory DCs(rDCs) that produce low levels of pro-inflammatory cytokines [interleukin(IL)-1β,IL-6,IL-12,interferon(IFN)-γ and tumor necrosis factor(TNF)-α] while expressing high levels of immunoregulatory cytokines(IL-10 and transforming growth factor-β).In addition,rDCs generated by cinnamon extract inhibited APC-dependent T-cell proliferation,and converted CD4+ T cells into IL-10high CD4+ T cells.Furthermore,oral administration of cinnamon extract inhibited development and progression of intestinal colitis by inhibiting expression of COX-2 and pro-inflammatory cytokines(IL-1β,IFN-γ and TNF-α),while enhancing IL-10 levels.CONCLUSION:Our study suggests the potential of cinnamon extract as an anti-inflammatory agent by targeting the generation of regulatory APCs and IL-10+ regulatory T cells.
文摘Presentation of antigenic peptide to T cells by major histocompatibility complex (MHC) class I molecules is the key to the cellular immune response.Non-self intracellular proteins are processed into short peptides and transported into endoplasmic reticulum (ER) where they are assembled with class I molecules assisted by several chaperone proteins to form trimeric complex.MHC class I complex loaded with optimised peptides travels to the cell surface of antigen presentation cells to be recognised by T cells.The cells presenting non-self peptides are cleared by CD8 positive T cells.In order to ensure that T cells detect an infection or mutation within the target cells the process of peptide loading and class I expression must be carefully regulated.Many of the cellular components involved in antigen processing and class I presentation are known and their various functions are now becoming clearer.Cellular & Molecular Immunology.2004;1(1):22-30.
基金supported by funding from the German Research Foundation(DFG),Collaborative Research grants within the CRC841(SFB841:"Liver inflammation:Infection,immune regulation und consequences"),projects B01 to A.K.H.and G.T.,B09 to L.D.the Clinical Research Group KF0306("Primary Sclerosing Cholangitis"),project 04 to G.T.
文摘The liver is an important immunological organ that controls systemic tolerance.The liver harbors professional and unconventional antigen-presenting cells that are crucial for tolerance induction and maintenance.Orchestrating the immune response in homeostasis depends on a healthy and well-toned immunological liver microenvironment,which Is maintained by the crosstalk of liver-resident antigen-presenting cells and intrahepatic and liver-infiltrating leukocytes.In response to pathogens or autoantigens,tolerance is disrupted by unknown mechanisms.Intrahepatic parenchymal and nonparenchymal cells exhibit unique antigen-presenting properties.The presentation of microbial and endogenous lipid-,metabolite-and peptide-derived antigens from the gut via conventional and nonconventional mechanisms can educate intrahepatic immune cells and elicit effector responses or tolerance.Perturbation of this balance results in autoimmune liver diseases,such as autoimmune hepatitis,primary biliary cholangitis,and primary sclerosing cholangitis.Although the exact etiologies of these autoimmune liver diseases are unknown,it is thought that the disruption of tolerance towards self-antigens and microbial metabolites and lipids,as well as alterations in bile acid composition,may result in changes in effector cell activation and polarization and may reduce or impair protective antiinflammatory regulatory T and B cell responses.Additionally,the canonical and noncanonical transmission of antigens and antigen:MHC complexes via trogocytosis or extracellular vesicles between different(non)immune cells in the liver may play a role in the induction of hepatic inflammation and tolerance.Here,we summarize emerging aspects of antigen presentation,autoantibody production,and the application of novel therapeutic approaches in the characterization and treatment of autoimmune liver diseases.
基金Supported by Natural Science Foundation of Beijing "Effect of porcine skin-derived dendritic cells on PCV infection" (6062006)Beijing Organization Department Project"Influence of PCV infection on bone marrow cell differentiation" (20061D0502100282)~~
文摘[Objective] This study aimed to investigate the changes of the transcriptional levels of molecules associated with endogenous antigen processing and presenta- tion in porcine skin-derived dendritic cells infected with PCV2 in vivo. [Method] Healthy 40-day-old Landrace piglets were infected with porcine circovirus type 2 （PCV2） and euthanized on the 34, 7rd, 14th, 21st and 35th d post inoculation （DPI）. The porcine skin-derived dendritic cells （DCs） were collected to analyze the transcrip- tional levels of molecules （LMP7, UBP, MHC-I, calreticulin） associated with endogenous antigen processing and presentation by using real-time fluorescent quantitative PCR （real-time FQ-PCR）. [Result] The results showed that the level of LMP7 mR- NAs was reduced significantly on the 3DPI （P〈0.05）; the level of UBP mRNAs was consistently up-regulated, which increased significantly on the 21DPI and 35DPI （P〈 0.05）; the level of MHC-I mRNAs was significantly down-regulated on the 7DPI （P〈 0.05）; the level of calreticulin mRNAs was up-regulated slightly without significant dif- ference. [Conclusion] PCV2 can inhibit the endogenous antigen processing and presentation ability of porcine skin-derived DCs at early stages of infection.
基金the NIH for support of this research(P41EB028239)the National Science Foundation Graduate Research Fellowship(Nos.DGE-1746891(SEW)and DGE-1746891(SRS)).
文摘Adoptive cell therapy(ACT)is an immunotherapy strategy for cancer that has seen widespread clinical success.During ACT,patient-derived lymphocytes are stimulated with the antigen of interest ex vivo,proliferated,then returned to the patient to initiate an antigen-specific antitumor response.While effective,this process is resource-intensive and logistically impossible for many patients.Particulate artificial antigen presenting cells(aAPCs)offer a potential“off-the-shelf”alternative to ex vivo ACT.While particulate aAPCs perform well in vitro,they have had limited success in vivo due to poor bioavailability after injection.Barriers to bioavailability include rapid clearance,unfavorable biodistribution,and inadequate interactions with CD8+T cells at sites of interest.Biomaterial properties such as elasticity have been shown to vastly impact the bioavailability and particle-cell interactions,but this has yet to be investigated in the context of aAPCs for in vivo T-cell stimulation.Previous literature likewise indicates that biomaterial properties,especially elasticity,can modulate T-cell activation in vitro.With the goal of creating a more biomimetic,next-generation particulate aAPC,we developed a poly(ethylene)glycol hydrogel particle platform with tunable elasticity to investigate the impact of elasticity on antigen-specific T cell activation for in vivo adoptive transfer.Using this knowledge,we were able to gain more precise control over in vivo T cell activation and investigate possible mechanisms including the effects of aAPC elasticity on T cell binding,macrophage uptake,and the protein corona.
文摘The intestinal immune system maintains tolerance to harmless food proteins and gut microbiota through peripherally derived RORγt+Tregs(pTregs),which prevent food intolerance and inflammatory bowel disease.Recent studies suggested that RORγt+antigen-presenting cells(APCs),which encompass rare dendritic cell(DC)subsets and type 3 innate lymphoid cells(ILC3s),are key to pTreg induction.Here,we developed a mouse with reduced RORγt+APCs by deleting a specific cis-regulatory element of Rorc encoding RORγt.Single-cell RNA sequencing and flow cytometry analyses confirmed the depletion of a RORγt+DC subset and ILC3s.These mice showed a secondary reduction in pTregs,impaired tolerance to oral antigens,and an increase in T helper(Th)2 cells.Conversely,ILC3-deficient mice showed no pTregs or Th2 cell abnormalities.Lineage tracing revealed that RORγt+DCs share a lymphoid origin with ILC3s,consistent with their similar phenotypic traits.These findings highlight the role of lymphoid RORγt+DCs in maintaining intestinal immune balance and preventing conditions like food allergies.
基金ThisstudywassupportedbyresearchgrantfromNationalNaturalScienceFoundationofChina (No 30 2 6 0 0 4 1 ) andbyresearchgrantsfromNaturalScienceFoundationofGuangxiZhuangAutonomousZoneChina (No 0 2 2 90 2 3)
文摘Background Antigen loaded eosinophils (EOSs) instilled intratracheally into mice were capable of inducing Th2 type cytokine production in the draining lymph nodes The aim of the present study was to evaluate whether EOSs within the tracheobronchial lumen can stimulate Th2 cell expansion in the lung tissues Methods Airway EOSs were recovered from ovalbumin sensitized and challenged BALB/c mice, these EOSs were then cocultured with CD4 + cells isolated from sensitized mice in the absence or presence of anti CD80 or/and CD86 monoclonal antibodies Airway EOSs were instilled into the trachea of sensitized mice. At the day 3 thereafter, the lung tissues were removed and prepared into cell suspensions for culture Cell free culture supernatants were collected for detection of cytokines Results Airway EOSs functioned as CD80 and CD86 dependent antigen presenting cells to stimulate lung CD4 + lymphocytes to produce interleukin 4, interleukin 5 and interleukin 13, but not interferon γ in in vitro assay When instilled intratracheally in sensitized recipient mice, airway EOSs primed lung Th2 cells in vivo for interleukin 4, interleukin 5 and interleukin 13, but not interferon γ, production during the in vitro culture that was also CD80 and CD86 dependent Conclusion EOSs within the lumina of airways could process inhaled antigen and function in vitro and in vivo as antigen presenting cells to promote expansion of Th2 cells in the lungs
文摘Administered in vivo, covalent receptor-recognized α2-macroglobulin (α2M*)-antigen complexes enhance humoral and cell-mediated immunity. We hypothesized that in vivo α2M*-encapsulation could be promoted in the setting of vaccines that co-deliver α2M* with unbound antigen, thereby eliminating the need to prepare complexes in vitro. Mice immunized intradermally with co-delivered α2M* and OVA demonstrated antigen-specific immune responses, including anti-tumor responses, similar to those elicited by conjugated α2M*-OVA complexes. Enhanced immunity appears to result from in vivo α2M*-encapsulation of antigen. This finding represents a significant advancement in the development of α2M* as an antigen delivery vehicle capable of enhancing the presentation of subunit vaccines.
基金supported by the Regional Joint Fund of the National Natural Science Foundation of China(U23A20255)the National Natural Science Foundation of China(32102827 and 31972818)the Natural Science Foundation of Guangdong Province(2023A1515011697 and 2023A1515012201).
文摘Innate immunity in fish is critically important for preventing the entry of pathogenic microorganisms by adeptly recognizing pathogen-associated molecular patterns(PAMPs)through pattern recognition receptors(PRRs).Concurrently,the adaptive immune response equips the vertebrate immune system to identify and retain memory of specific pathogens,thereby facilitating enhanced secondary responses upon re-exposure.Antigen-presenting cells(APCs)are integral to this process,as they recognize antigens via mechanisms including PRRs,internalize them,and process these antigens for presentation to T cells.This interaction triggers the activation of both T cells and B cells,initiating a robust priming of the adaptive immune system and establishing a functional bridge between innate and adaptive immunity.Antigen presentation serves as a pivotal mechanism for T cell activation and B cell differentiation,thereby leading to the establishment of effective antimicrobial protection.Vaccination of fish is of paramount importance for preventing specific infectious diseases and is economically and environmentally essential for the development of a sustainable fish aquaculture industry.The design of efficacious vaccines necessitates the establishment of long-term protection against specific antigenic challenges,with APCs occupying a central role in this endeavor.This review summarizes the most recent studies on fish antigen presentation pathways and elucidates the mechanisms involved in the recognition,processing,and presentation of antigens by APCs,triggering activation of T cells.Moreover,this review highlights recent findings concerning immune regulatory factors that activate adaptive immunity,including adjuvants and immunostimulants,providing the prospects for fish vaccine applications.A comprehensive understanding of how fish APCs detect and respond to antigens will have profound implications for the future development of tailored vaccination strategies and the rational design of interventions against infectious diseases impacting the commercial aquaculture sector.
文摘An immunostimulatory factor was identified to be secreted by antigen-pulsed maorophages. This factor was able to induce the generation of antigen specific T helper lymphocytes in vitro as well as in vivo. Further in vitro experiments testing for the genetic restriction of this factor indicated that it is a genetically-restricted antigen specific factor (ASF). The Cunningham plaque assay was used to quantify the generation of T helper lymphocytes by measuring the number of plaque forming cells after sequential incubations of antigen-pulsed maorophages with T lymphocytes, and then spleen cells, and finally the TNP-coated sheep red blood cells.
文摘Human endoplasmic reticulum aminopeptidase 1 (ERAP1) is one of two ER luminal aminopeptidases that participate in the final processing of peptide precursors and generates the N-termini of the MHC class I-restricted epitopes. In order to investigate the interactions of its binding site with substrate peptides, X-ray crystallographic analyses have been carried out to study structures of ERAP1 regulatory (ERAP1_R) domain in complex with antigenic peptides. Single-chain bimodular constructs with various antigenic peptides linked to the C-terminal end of ERAP1_R domain are designed to facilitate crystallization process of these complexes. These recombinant proteins have been purified and crystalized, and x-ray diffraction data of one crystal have been processed to a resolution of 2.8 . The crystal belongs to the space group P21, with unit cell parameters a =64.2, b = 66.8, c = 66.3 , β = 110.2°. A Refmac-refined omit map reveals a clear density for the antigenic peptide’s carboxylate-end that is in contact with the ERAP1 regulatory domain of neighboring molecule. Thus the single-chain bimodular constructs have provided an expedited approach to study sequence-specific interactions between the ERAP1 regulatory domain and antigen peptide’s C-terminal ends.
基金supported by the National Key Research and Development Program of China(2021YFA0909400)the National Natural Science Foundation of China(22425505,32301099,and 21834007)+2 种基金the Shanghai Sailing Program(22YF1424200)the Interdisciplinary Program of Shanghai Jiao Tong University(YG2022QN032)the Xiangfu Lab Research Project(XF012022E0100).
文摘Immunization has long played essential roles in preventing diseases.However,the desire for precision delivery of vaccines to boost a robust immune response remains largely unmet.Here,we describe the use of acupoint delivery of nanovaccines(ADN)to elicit dual-niche immunological priming.ADN can simultaneously stimulate mast cell-assisted maturation of dendritic cells at the acupoint and enable direct delivery of nanovaccines into the draining lymph nodes.We demonstrate that ADN not only provokes antigen presentation by lymph node-resident CD8α^(+)dendritic cells,but also induces the accumulation of nanovaccines in B-cell zones,amplifying antigen-specific cytotoxic T lymphocyte responses and immunoglobulin G antibody expression in draining lymph nodes.ADN also generates systemic immune responses by causing immune memory and preventing T-cell anergy in the spleen.Further supported by evoking effective antitumor responses and high-level antiviral antibodies in mice,ADN provides a simple yet versatile platform for advanced nanovaccination.
