Background The mechanism of chronic immune activation and impairment of HIV-specific immune responses during chronic infection is not fully understood. However, it is known that high immune activation leads to more ra...Background The mechanism of chronic immune activation and impairment of HIV-specific immune responses during chronic infection is not fully understood. However, it is known that high immune activation leads to more rapid progression to AIDS. We hypothesize that CD4^＋ T cell-mediated viral antigen presentation contributes to this pathologic immune activation in HIV-infected individuals. Methods HIV-specific T cells, responding to noninfectious HIV-1 virions as antigen, were measured by flow cytometric assays. These experimental conditions reflect the in vivo condition where noninfectious HIV-1 represents more than 99% of the antigens. Results CD4^＋ T cells purified from HIV-infected individuals were capable of cross presenting exogenous noninfectious HIV-1 virions to HIV-1-specific CD8^＋ T cells. Cross presentation required the entry of HIV-1 to CD4^＋ T cells and antigen translocation from endoplasmic reticulum to the Golgi complex. Blocking CD4^＋ mediated activation of HIV-specific CD8^＋ T cells and redirecting the viral antigens to antigen presenting cells improved HIV-specific T cell responses. Contusions One possible cause of chronic immune activation and impairment of HIV-1 specific T cell responses is represented by HIV-1 harboring CD4^＋ T cells cross presenting HIV-1 antigen to activate CD8^＋ T cells. This new mechanism provides the first evidence that cross presentation of noninfectious HIV-1 virions play a role in the immunopathogenesis of HIV-1 infection.展开更多
Host and viral factors deeply influence the human immunodeficiency virus(HIV) disease progression. Among them human leukocyte antigen(HLA) locus plays a key role at different levels. In fact, genes of the HLA locus ha...Host and viral factors deeply influence the human immunodeficiency virus(HIV) disease progression. Among them human leukocyte antigen(HLA) locus plays a key role at different levels. In fact, genes of the HLA locus have shown the peculiar capability to modulate both innate and adaptive immune responses. In particular, HLA class Ⅰmolecules are recognized by CD8+ T-cells and natural killers(NK) cells towards the interaction with T cell receptor(TCR) and Killer Immunoglobulin Receptor(KIR) 3DL1 respectively. Polymorphisms within the different HLA alleles generate structural changes in HLA classⅠpeptide-binding pockets. Amino acid changes in the peptide-binding pocket lead to the presentation of a different set of peptides to T and NK cells. This review summarizes the role of HLA in HIV progression toward acquired immunodeficiency disease syndrome and its receptors. Recently, many studies have been focused on determining the HLA binding-peptides. The novel use of immune-informatics tools, from the prediction of the HLA-bound peptides to the modification of the HLAreceptor complexes, is considered. A better knowledge of HLA peptide presentation and recognition are allowing new strategies for immune response manipulation to be applied against HIV virus.展开更多
One important aspect of mesenchymal stromal cells （MSCs）-mediated immunomodulation is the recruitment and induction of regulatory T （Treg） cells. However, we do not yet know whether MSCs have similar effects on th...One important aspect of mesenchymal stromal cells （MSCs）-mediated immunomodulation is the recruitment and induction of regulatory T （Treg） cells. However, we do not yet know whether MSCs have similar effects on the other subsets of Treg cells. Herein, we studied the effects of MSCs on CD8＋CD28- Treg cells and found that the MSCs could not only increase the proportion of CD8＋CD28- T cells, but also enhance CD8＋CD28-T cells＇ ability of hampering naive CD4＋ T-cell proliferation and activation, decreasing the production of IFN-γ by activated CD4＋ T cells and inducing the apoptosis of activated CD4＋ T cells. Mechanistically, the MSCs affected the functions of the CD8＋CD28- T cells partially through moderate upregulating the expression of IL-10 and FasL. The MSCs had no distinct effect on the shift from CD8＋CD28＋ T cells to CD8＋CD28- T cells, but did increase the proportion of CD8＋CD28- T cells by reducing their rate of apoptosis. In summary, this study shows that MSCs can enhance the regulatory function of CD8＋CD28- Treg cells, shedding new light on MSCs-mediated immune regulation.展开更多
The expression of major histocompatibility complex class I(MHC-I),a key antigen-presenting protein,can be induced in dopaminergic neurons in the substantia nigra,thus indicating its possible involvement in the occurre...The expression of major histocompatibility complex class I(MHC-I),a key antigen-presenting protein,can be induced in dopaminergic neurons in the substantia nigra,thus indicating its possible involvement in the occurrence and development of Parkinson’s disease.However,it remains unclear whether oxidative stress induces Parkinson’s disease through the MHC-I pathway.In the present study,polymerase chain reaction and western blot assays were used to determine the expression of MHC-I in 1-methyl-4-phenylpyridinium(MPP+)-treated SH-SY5Y cells and a 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine(MPTP)-induced Parkinson’s disease mouse model.The findings revealed that MHC-I was expressed in both models.To detect whether the expression of MHC-I was able to trigger the infiltration of cytotoxic T cells,immunofluorescence staining was used to detect cytotoxic cluster of differentiation 8(CD8)+T cell infiltration in the substantia nigra of MPTP-treated mice.The results indicated that the presentation of MHC-I in dopaminergic neurons was indeed accompanied by an increase in the number of CD8+T cells.Moreover,in MPTP-induced Parkinson’s disease model mice,the genetic knockdown of endogenous MHC-I,which was caused by injecting specific adenovirus into the substantia nigra,led to a significant reduction in CD8+T cell infiltration and alleviated dopaminergic neuronal death.To further investigate the molecular mechanisms of oxidative stress-induced MHC-I presentation,the expression of PTEN-induced kinase 1(PINK1)was silenced in MPP+-treated SH-SY5Y cells using specific small interfering RNA(siRNA),and there was more presentation of MHC-I in these cells compared with control siRNA-treated cells.Taken together,MPP+-/MPTP-induced oxidative stress can trigger MHC-I presentation and autoimmune activation,thus rendering dopaminergic neurons susceptible to immune cells and degeneration.This may be one of the mechanisms of oxidative stress-induced Parkinson’s disease,and implies the potential neuroprotective role of PINK1 in oxidative stress-induced MHC-I presentation.All animal experiments were approved by the Southern Medical University Ethics Committee(No.81802040,approved on February 25,2018).展开更多
Major mechanisms for the recognition of pathogens by immune cells have evolved to employ classical and non-classical major histocompatibility complex class I （MHC I） molecules. Classical MHC I molecules present anti...Major mechanisms for the recognition of pathogens by immune cells have evolved to employ classical and non-classical major histocompatibility complex class I （MHC I） molecules. Classical MHC I molecules present antigenic peptide ligands on infected cells to CD8＋ T cells, whereas a key function for non-classical MHC I molecules is to mediate inhibitory or activating stimuli in natural killer （NK） cells. The structural diversity of MHC I puts immense pressure on persisting viruses, including cytomegaloviruses. The very large coding capacity of the human cytomegalovirus allows it to express a whole arsenal of immunoevasive factors assigned to individual MHC class I targets. This review summarizes achievements from more than two decades of intense research on how human cytomegalovirus manipulates MHC I molecules and escapes elimination by the immune system.展开更多
基金This study was supported by a grant from the Major Basic Project of China (973) (No. 2005CB522903).
文摘Background The mechanism of chronic immune activation and impairment of HIV-specific immune responses during chronic infection is not fully understood. However, it is known that high immune activation leads to more rapid progression to AIDS. We hypothesize that CD4^＋ T cell-mediated viral antigen presentation contributes to this pathologic immune activation in HIV-infected individuals. Methods HIV-specific T cells, responding to noninfectious HIV-1 virions as antigen, were measured by flow cytometric assays. These experimental conditions reflect the in vivo condition where noninfectious HIV-1 represents more than 99% of the antigens. Results CD4^＋ T cells purified from HIV-infected individuals were capable of cross presenting exogenous noninfectious HIV-1 virions to HIV-1-specific CD8^＋ T cells. Cross presentation required the entry of HIV-1 to CD4^＋ T cells and antigen translocation from endoplasmic reticulum to the Golgi complex. Blocking CD4^＋ mediated activation of HIV-specific CD8^＋ T cells and redirecting the viral antigens to antigen presenting cells improved HIV-specific T cell responses. Contusions One possible cause of chronic immune activation and impairment of HIV-1 specific T cell responses is represented by HIV-1 harboring CD4^＋ T cells cross presenting HIV-1 antigen to activate CD8^＋ T cells. This new mechanism provides the first evidence that cross presentation of noninfectious HIV-1 virions play a role in the immunopathogenesis of HIV-1 infection.
文摘Host and viral factors deeply influence the human immunodeficiency virus(HIV) disease progression. Among them human leukocyte antigen(HLA) locus plays a key role at different levels. In fact, genes of the HLA locus have shown the peculiar capability to modulate both innate and adaptive immune responses. In particular, HLA class Ⅰmolecules are recognized by CD8+ T-cells and natural killers(NK) cells towards the interaction with T cell receptor(TCR) and Killer Immunoglobulin Receptor(KIR) 3DL1 respectively. Polymorphisms within the different HLA alleles generate structural changes in HLA classⅠpeptide-binding pockets. Amino acid changes in the peptide-binding pocket lead to the presentation of a different set of peptides to T and NK cells. This review summarizes the role of HLA in HIV progression toward acquired immunodeficiency disease syndrome and its receptors. Recently, many studies have been focused on determining the HLA binding-peptides. The novel use of immune-informatics tools, from the prediction of the HLA-bound peptides to the modification of the HLAreceptor complexes, is considered. A better knowledge of HLA peptide presentation and recognition are allowing new strategies for immune response manipulation to be applied against HIV virus.
基金This study was supported by the National Basic Research Program of China （2012CBA01302, 2010CB945400）, the National Natural Science Foundation of China （31171398, 81271265, 81425016）, the Key Scientific and Technological Projects of Guangdong Province （2007A032100003）, the Natural Science Foundation of Guangdong Province （ S2013030013305 ）, the Key Scientific and Technological Program of Guangzhou City （201400000003-3, 201300000089, 2010U1-E00551 ） and Guangdong Department of Science ＆ Technology Translational Medicine Center grant （2011A080300002）.
文摘One important aspect of mesenchymal stromal cells （MSCs）-mediated immunomodulation is the recruitment and induction of regulatory T （Treg） cells. However, we do not yet know whether MSCs have similar effects on the other subsets of Treg cells. Herein, we studied the effects of MSCs on CD8＋CD28- Treg cells and found that the MSCs could not only increase the proportion of CD8＋CD28- T cells, but also enhance CD8＋CD28-T cells＇ ability of hampering naive CD4＋ T-cell proliferation and activation, decreasing the production of IFN-γ by activated CD4＋ T cells and inducing the apoptosis of activated CD4＋ T cells. Mechanistically, the MSCs affected the functions of the CD8＋CD28- T cells partially through moderate upregulating the expression of IL-10 and FasL. The MSCs had no distinct effect on the shift from CD8＋CD28＋ T cells to CD8＋CD28- T cells, but did increase the proportion of CD8＋CD28- T cells by reducing their rate of apoptosis. In summary, this study shows that MSCs can enhance the regulatory function of CD8＋CD28- Treg cells, shedding new light on MSCs-mediated immune regulation.
基金This work was supported by the National Natural Science Foundation of China,Nos.81671240(to SZZ),81560220(to GHL)the Youth Science Foundation of Jiangxi Province of China,No.20151BAB215014(to GHL)Health and Family Planning Commission of Jiangxi Province of China,No.20195109(to GHL)。
文摘The expression of major histocompatibility complex class I(MHC-I),a key antigen-presenting protein,can be induced in dopaminergic neurons in the substantia nigra,thus indicating its possible involvement in the occurrence and development of Parkinson’s disease.However,it remains unclear whether oxidative stress induces Parkinson’s disease through the MHC-I pathway.In the present study,polymerase chain reaction and western blot assays were used to determine the expression of MHC-I in 1-methyl-4-phenylpyridinium(MPP+)-treated SH-SY5Y cells and a 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine(MPTP)-induced Parkinson’s disease mouse model.The findings revealed that MHC-I was expressed in both models.To detect whether the expression of MHC-I was able to trigger the infiltration of cytotoxic T cells,immunofluorescence staining was used to detect cytotoxic cluster of differentiation 8(CD8)+T cell infiltration in the substantia nigra of MPTP-treated mice.The results indicated that the presentation of MHC-I in dopaminergic neurons was indeed accompanied by an increase in the number of CD8+T cells.Moreover,in MPTP-induced Parkinson’s disease model mice,the genetic knockdown of endogenous MHC-I,which was caused by injecting specific adenovirus into the substantia nigra,led to a significant reduction in CD8+T cell infiltration and alleviated dopaminergic neuronal death.To further investigate the molecular mechanisms of oxidative stress-induced MHC-I presentation,the expression of PTEN-induced kinase 1(PINK1)was silenced in MPP+-treated SH-SY5Y cells using specific small interfering RNA(siRNA),and there was more presentation of MHC-I in these cells compared with control siRNA-treated cells.Taken together,MPP+-/MPTP-induced oxidative stress can trigger MHC-I presentation and autoimmune activation,thus rendering dopaminergic neurons susceptible to immune cells and degeneration.This may be one of the mechanisms of oxidative stress-induced Parkinson’s disease,and implies the potential neuroprotective role of PINK1 in oxidative stress-induced MHC-I presentation.All animal experiments were approved by the Southern Medical University Ethics Committee(No.81802040,approved on February 25,2018).
文摘Major mechanisms for the recognition of pathogens by immune cells have evolved to employ classical and non-classical major histocompatibility complex class I （MHC I） molecules. Classical MHC I molecules present antigenic peptide ligands on infected cells to CD8＋ T cells, whereas a key function for non-classical MHC I molecules is to mediate inhibitory or activating stimuli in natural killer （NK） cells. The structural diversity of MHC I puts immense pressure on persisting viruses, including cytomegaloviruses. The very large coding capacity of the human cytomegalovirus allows it to express a whole arsenal of immunoevasive factors assigned to individual MHC class I targets. This review summarizes achievements from more than two decades of intense research on how human cytomegalovirus manipulates MHC I molecules and escapes elimination by the immune system.
