HIV-Specific IL-2^+ and/or IFN-γ^+ CD8^+ T Cell Reponses during Chronic HIV-1 Infection in Former Blood Donors

Objective Conflicting data have been generated from previous studies to determine which kind of relationship exists between HIV-1 specific CD8 Tcell responses and HIV-1 viral load or CD4 count over the course of infection.In this study,153 HIV-1 infected LTNPs were enrolled to investigate the role of HIV-1 specific CD8 T-cell responses in chronic HIV-1 infection among HIV-1 infected former blood donors.Methods The patients were stratified into three groups according to CD4 count：CD4≥500 cells/μL;350 cells/μL≤CD4〈500 cells/μL;CD4〈350 cells/μL.PBMCs were isolated from the patients＇ anticoagulated blood samples.IL-2 and IFN-γ secretions of CD 8 T cells against 17 HIV-1 consensus B full peptide pools were analyzed by using ICS assay.Results An overall inverse correlation were observed between CD4 count and plasma viral load.Although no significant difference was observed during the comparisons of frequency/breadth of HIV-1 specific CD8 T cell responses,CD4 count stratification analysis showed that different correlation pattern existed in three strata：as for patients whose CD4 counts were less than 350 cells/μL,no significant correlations were identified between frequency/breadth of HIV-1 specific CD8 T cell responses and CD4 count/viral load;as for patients whose CD4 counts ranged from 350 cells /μL to 500 cells/μL,significant correlation was only observed between the response breadth of IL-2＋IFN-γ＋ CD8 T cells and CD4 count;however,as for patients whose CD4 counts were more than 500 cells/μL,direct correlations were identified between IL-2＋IFN-γ＋/IL-2＋/IFN-γ＋ CD8 T cells and viral load or CD4 count.Conclusions Universal consistent inverse correlation was only indentified between CD4 count and viral load.The relationship between HIV-1 specific CD8 T cell responses and CD4 count/viral load varied in different CD4 strata,which showed that better preserved CD4 T cells were correlated with better CD8 T cell functions.

Memory Phenotypes of HIV-Specific CD8+ T Cell Responses Are Independent of Functional Activity as Defined by Cytokine Output

Objectives: The definition of CD8+ T cell attributes that mediate protective immunity in HIV dis-ease progression has not been clearly defined. Although our ability to characterize these cells continues to improve, the extent to which specific memory phenotypic categories of CD8+ T cells reliably represent their functional attributes remains controversial. Methods: We simultaneously assessed surface phenotype and functionality of HIV-specific CD8+ T cells by multiparametric flow cytometry, measuring five CD8+ T cell functions (CD107a, IFNγ, MIP-1β, TNFα and IL2) and phenotypic markers CCR7, CD45RA, and CD27, in parallel in 24 HIV-infected individuals. Results: Virus-specific responses were contained within all eight phenotypic categories defined using CCR7, CD45RA, and CD27. Phenotypic profiles of HIV-specific cells differed from CEF-specific cells, with HIV-specific cells having higher levels of CD45RA (p = 0.008). Interestingly a large portion of CEF and HIV-specific cells were found within previously undefined phenotypes CCR7+CD27-CD45RA+ (14.6% and 17.2%, respectively) and CCR7+CD27-CD45RA-(14.8% and 15.8%, respectively). In addition, up to 10% - 20% of responding cells were phenotypically “naive”. Additionally, memory phenotypes of cells exhibiting monofunctional and polyfunctional responses frequently differed, and failed to associate with a consistent phenotype representing functionally active cells. Conclusion: These data suggest that particularly after antigen stimulation, that surface phenotypes defined by CCR7, CD27 and CD45RA expression on antigen-specific CD8+ T cells, reflect a wide range of immunological functions, and that no single phenotype defined by memory marker expression can reliably be used to identify functional capacity.

Berberine improves central memory formation of CD8^(+)T cells:Implications for design of natural product-based vaccines

Berberine(BBR)as one of the most effective natural products has been increasingly used to treat various chronic diseases due to its immunosuppressive/tolerogenic activities.However,it is unknown if BBR can be applied without abrogating the efforts of vaccination.Here we show that priming of CD8^(+)T cells in the presence of BBR lead to improved central memory formation(Tcm)with substantially reduced effector proliferation,primarily orchestrated through activation of AMPK and Stat5.Tcm derived from vaccinated mice fed with BBR were able to adoptively transfer protective immunity to naIve recipients.Vaccination of BBR-fed mice conferred better memory protection against infection without losing immediate effector efficacy,suggesting appreciable benefits from using BBR in vaccination.Thus,our study may help to lay the groundwork for mechanistic understanding of the immunomodulatory effects of natural products and their potential use as adjuvant that allows the design of novel vaccines with more desirable properties.

Impact of T cells on hematopoietic stem and progenitor cell function:Good guys or bad guys?

When hematopoietic stem and progenitor cells(HSPC)are harvested for transplantation, either from the bone marrow or from mobilized blood, the graft contains a significant number of T cells. It is these T cells that are the major drivers of graft-vs-host disease(Gv HD). The risk for Gv HD can simply be reduced by the removal of these T cells from the graft. However, this is not always desirable, as this procedure also decreases the engraftment of the transplanted HSPCs and, if applicable, a graft-vs-tumor effect. This poses an important conundrum in the field: T cells act as a double-edged sword upon allogeneic HSPC transplantation, as they support engraftment of HSPCs and provide anti-tumor activity, but can also cause Gv HD. It has recently been suggested that T cells also enhance the engraftment of autologous HSPCs, thus supporting the notion that T cells and HSPCs have an important functional interaction that is highly beneficial, in particular during transplantation. The underlying reason on why and how T cells contribute to HSPC engraftment is still poorly understood. Therefore, we evaluate in this review the studies that have examined the role of T cells during HSPC transplantation and the possible mechanisms involved in their supporting function. Understanding the underlying cellular and molecular mechanisms can provide new insight into improving HSPC engraftment and thus lower the number of HSPCs required during transplantation. Moreover, it could provide new avenues to limit the development of severe Gv HD, thus making HSPC transplantations more efficient and ultimately safer.

IL-15 increases the frequency of effectormemory CD8^(+) T cells in rhesus monkeys immunized with HIV vaccine

Several studies have suggested that interleukin(IL)-15 is a promising adjuvant that promotes cellular immunity when administered with human immunodeficiency virus(HIV)vaccine.Here we evaluated the effect of IL-15 plasmid on HIV-specific immune responses,especially cellular immunity,in eight rhesus monkeys.These monkeys were immunized three times with HIV DNA vaccine with or without IL-15 plasmid and boosted with recombinant Tiantan strain vaccinia virus-based HIV vaccine(rTV)22 weeks after the first immunization.Although we did not detect any significant differences in the HIV-specific CD81 T-cell response between monkeys with IL-15 coimmunization and monkeys with HIV vaccine alone,our results showed that the frequency of effector CD8^(+) memory T cells in the peripheral blood was significantly higher in monkeys with IL-15 coimmunization than those with HIV vaccine alone at almost all of the time points examined.Furthermore,the titers of anti-HIV antibodies were higher in Group T than those in Group C after rTV boosting.These findings in rhesus monkeys suggest that IL-15 may be useful as a cytokine adjuvant for HIV vaccine.

Defect of CD8^+ Memory T Cells Developed in Absence of IL-12 Priming for Secondary Expansion

IL-12 priming plays an important role in stimulation of CD8^＋ effector T cells and development of CD8^＋ memory T （Tm） cells. However, the functional alteration of CD8^＋ Tm cells developed in the absence of IL-12 priming is elusive. In this study, we investigated the capacity of secondary expansion of CD8~ Tm cells developed from transgenic OT I CD8^＋ T cells. The latter cells were in vitro and in vivo stimulated by ovalbumin （OVA）-pulsed dendritic cells [DCovA and （IL-12^-/-）DCovA] derived from wild-type C57BL/6 and IL-12 gene knockout mice, respectively. We demonstrated that IL-12 priming is important not only in CD8^＋ T cell clonal expansion, but also in generation of CD8^＋ Tm cells with the capacity of secondary expansion upon antigen re-encounter. However, IL-12 signaling is not involved in CD8^＋ Tm cell survival and recall responses. Therefore, this study provides useful information for vaccine design and development. Cellular ＆ Molecular Immunology.

Mettl3依赖的m^(6)A甲基化调控CD8^(+)T细胞效应分化和记忆形成

Efficient immune responses rely on the proper differentiation of CD8^(+)T cells into effector and memory cells.Here,we show a critical requirement of N^6-Methyladenosine(m^(6)A)methyltransferase Mettl3 during CD8^(+)T cell responses upon acute viral infection.Conditional deletion of Mettl3 in CD8^(+)T cells impairs effector expansion and terminal differentiation in an m^(6)A-dependent manner,subsequently affecting memory formation and the secondary response of CD8^(+)T cells.Our combined RNA-seq and m^(6)AmiCLIP-seq analyses reveal that Mettl3 deficiency broadly impacts the expression of cell cycle and transcriptional regulators.Remarkably,Mettl3 binds to the Tbx21 transcript and stabilizes it,promoting effector differentiation of CD8^(+)T cells.Moreover,ectopic expression of T-bet partially restores the defects in CD8^(+)T cell differentiation in the absence of Mettl3.Thus,our study highlights the role of Mettl3 in regulating multiple target genes in an m^(6)A-dependent manner and underscores the importance of m^(6)A modification during CD8^(+)T cell response.

Role of autoreactive Tc17 cells in the pathogenesis of experimental autoimmune encephalomyelitis

Background:The pathogenesis of multiple sclerosis(MS)and experimental autoimmune encephalomyelitis(EAE-an animal model of MS)is primarily mediated by T cells.However,recent studies have only focused on interleukin(IL)-17-secreting CD4^(+)T-helper cells,also known as Th17 cells.This study aimed to compare Th17 cells and IL-17-secreting CD8^(+)T-cytotoxic cells(Tc17)in the context of MS/EAE.Methods:Female C57BL/6 mice were immunized with myelin oligodendrocyte glycoprotein peptides 35-55(MOG35-55),pertussis toxin,and complete Freund's adjuvant to establish the EAE animal model.T cells were isolated from the spleen(12-14 days postimmunization).CD4^(+)and CD8^(+)T cells were purified using isolation kit and then differentiated into Th17 and Tc17,respectively,using MOG35-55 and IL-23.The secretion levels of interferon-(IFN-γ)and IL-17 were measured via enzyme-linked immunosorbent assay using cultured CD4^(+)and CD8^(+)T cell supernatants.The pathogenicity of Tc17 and Th17 cells was assessed through adoptive transfer(tEAE),with the clinical course assessed using an EAE score(0-5).Hematoxylin and eosin as well as Luxol fast blue staining were used to examine the spinal cord.Purified CD8^(+)CD3^(+)and CD4^(+)CD3^(+)cells differentiated into Tc17 and Th17 cells,respectively,were stimulated with MOG35-55 peptide for proliferation assays.Results:The results showed that Tc17 cells(15,951±19855VS.55,709±4196cpm;p<0.050)exhibited a weaker response to highest dose(20μg/mL)MOG35-55 than Th17 cells.However,this response was not dependent on Th17 cells.After the 48h stimulation,at the highest dose(20μg/mL)of MOG35-55.Tc17 cells secreted lower levels of IFN-(280.00±15.00vs.556.67±15.28pg/mL,p<0.050)and IL-17(102.67±5.86 pg/mL vs.288.33±12.58 pg/mL;p<0.050)than Th17 cells.Similar patterns were observed for IFN-γsecretion at 96 and 144h.Furthermore,Tc17 cell-induced tEAE mice exhibited similar EAE scores to Th17 cell-induced tEAE mice and also showed similar inflammation and demyelination.Conclusion:The degree of pathogenicity of Tc17 cells in EAE is lower than that of Th17 cells.Future investigation on different immune cells and EAE models is warranted to determine the mechanisms underlying MS.

MHC class Ⅰ-independent activation of virtual memory CD8 T cells induced by chemotherapeutic agent-treated cancer cells

Cancer cells can evade immune recognition by losing major histocompatibility complex(MHC)class Ⅰ.Hence,MHC class Ⅰ-negative cancers represent the most challenging cancers to treat.Chemotherapeutic drugs not only directly kill tumors but also modulate the tumor immune microenvironment However,it remains unknown whether chemotherapy-treated cancer cells can activate CD8 T cells independent of tumor-derived MHC class Ⅰ and whether such MHC class Ⅰ-independent CD8 T-cell activation can be exploited for cancer immunotherapy.Here,we showed that chemotherapy-treated cancer cells directly activated CD8 T cells in an MHC class Ⅰ-independent manner and that these activated CD8 T cells exhibit virtual memory(VM)phenotypes.Consistently,in vivo chemotherapeutic treatment preferentially increased tumor-infiltrating VM CD8 T cells.Mechanistically,MHC class Ⅰ-independent activation of CD8 T cells requires cell-cell contact and activation of the PI3K pathway.VM CD8 T cells contribute to a superior therapeutic effect on MHC class Ⅰ-deficient tumors.Using humanized mouse models or primary human CD8 T cells,we also demonstrated that chemotherapy-treated human lymphomas activated VM CD8 T cells independent of tumor-derived MHC class Ⅰ.In conclusion,CD8 T cells can be directly activated in an MHC class Ⅰ-independent manner by chemotherapy-treated cancers,and these activated CD8 T cells may be exploited for developing new strategies to treat MHC class Ⅰ-deficient cancers.

TRAF2 regulates T cell immunity by maintaining a Tpl2-ERK survival signaling axis in effector and memory CD8 T cells

Generation and maintenance of antigen-specific effector and memory T cells are central events in immune responses against infections.We show that TNF receptor-associated factor 2(TRAF2)maintains a survival signaling axis in effector and memory CD8 T cells required for immune responses against infections.This signaling axis involves activation of Tpl2 and its downstream kinase ERK by NF-κB-inducing kinase(NIK)and degradation of the proapoptotic factor Bim.NIK mediates Tpl2 activation by stimulating the phosphorylation and degradation of the Tpl2 inhibitor p105.Interestingly,while NIK is required for Tpl2-ERK signaling under normal conditions,uncontrolled NIK activation due to loss of its negative regulator,TRAF2,causes constitutive degradation of p105 and Tpl2,leading to severe defects in ERK activation and effector/memory CD8 T cell survival.Thus,TRAF2 controls a previously unappreciated signaling axis mediating effector/memory CD8 T cell survival and protective immunity.

Human CD4 ＋ effector T lymphocytes generated upon TCR engagement with self-peptides respond defectively to IL-7 in their transition to memory cells

The peripheral repertoire of CD4＋ T lymphocytes contains autoreactive cells that remain tolerant through several mechanisms. However, nonspecific CD4＋ T cells can be activated in physiological conditions as in the course of an ongoing immune response, and their outcome is not yet fully understood. Here, we investigate the fate of human naive CD4＋ lymphocytes activated by dendritic cells （DCs） presenting endogenous self-peptides in comparison with lymphocytes involved in alloresponses. We generated memory cells （Tmem） from primary effectors activated with mature autologous DCs plus interleukin （IL）-2 （Tmauto）, simulating the circumstances of an active immune response, or allogeneic DCs （Tmallo）. Tmem were generated from effector cells that were rested in the absence of antigenic stimuli, with or without IL-7. Tmem were less activated than effectors （demonstrated by CD25 downregulation） particularly with IL-7, suggesting that this cytokine may favour the transition to quiescence. Tmauto and TmaHo showed an effector memory phenotype, and responded similarly to polyclonal and antigen-specific stimuli. Biochemically, IL-7-treated Tma^o were closely related to conventional memory lymphocytes based on Erk-l/2 activation, whereas Tmauto were more similar to effectors. Autologous effectors exhibited lower responses to IL-7 than allogeneic cells, which were reflected in their reduced proliferation and higher cell death. This was not related to IL-7 receptor expression but rather to signalling deficiencies, according to STAT5 activation These results suggest that ineffective responses to IL-7 could impair the transition to memory cells of naive CD4＋ T lymphocytes recognizing self-peptides in the setting of strong costimulation.

Regulation of CD8^(+)T memory and exhaustion by the mTOR signals

CD8^(+)T cells are the key executioners of the adaptive immune arm,which mediates antitumor and antiviral immunity.Naïve CD8^(+)T cells develop in the thymus and are quickly activated in the periphery after encountering a cognate antigen,which induces these cells to proliferate and differentiate into effector cells that fight the initial infection.Simultaneously,a fraction of these cells become long-lived memory CD8^(+)T cells that combat future infections.Notably,the generation and maintenance of memory cells is profoundly affected by various in vivo conditions,such as the mode of primary activation(e.g.,acute vs.chronic immunization)or fluctuations in host metabolic,inflammatory,or aging factors.Therefore,many T cells may be lost or become exhausted and no longer functional.Complicated intracellular signaling pathways,transcription factors,epigenetic modifications,and metabolic processes are involved in this process.Therefore,understanding the cellular and molecular basis for the generation and fate of memory and exhausted CD8^(+)cells is central for harnessing cellular immunity.In this review,we focus on mammalian target of rapamycin(mTOR),particularly signaling mediated by mTOR complex(mTORC)2 in memory and exhausted CD8^(+)T cells at the molecular level.

Functions of NKG2D in CD8^(+) T cells: an opportunity for immunotherapy

Natural killer group 2 member D(NKG2D)is a type II transmembrane receptor.NKG2D is present on NK cells in both mice and humans,whereas it is constitutively expressed on CD8+T cells in humans but only expressed upon T-cell activation in mice.NKG2D is a promiscuous receptor that recognizes stress-induced surface ligands.In NK cells,NKG2D signaling is sufficient to unleash the killing response;in CD8+T cells,this requires concurrent activation of the T-cell receptor(TCR).In this case,the function of NKG2D is to authenticate the recognition of a stressed target and enhance TCR signaling.CD28 has been established as an archetype provider of costimulation during T-cell priming.It has become apparent,however,that signals from other costimulatory receptors,such as NKG2D,are required for optimal T-cell function outside the priming phase.This review will focus on the similarities and differences between NKG2D and CD28;less well-described characteristics of NKG2D,such as the potential role of NKG2D in CD8+T-cell memory formation,cancer immunity and autoimmunity;and the opportunities for targeting NKG2D in immunotherapy.

Role of Triggering Receptor Expressed on Myeloid Cell-1 Expression in Mammalian Target of Rapamycin Modulation of CD8＋ T-cell Differentiation during the Immune Response to Invasive Pulmonary Aspergillosis

Background： Triggering receptor expressed on myeloid cell- 1 （TREM- 1） may play a vital role in mammalian target ofrapamycin （mTOR） modulation ofCD8＋ 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 roTOR signaling pathway modulates the proliferation and differentiation of CD8＋ T-cells during the immune response to I PA and the role TREM-1 plays in this process. Methods： Cyclophosphamide （CTX） was injected intraperitoneally, and Asl？e;gillus.[mnigams spore suspension was inoculated intranasally to establish the immunosuppressed IPA mouse model. After inoculation, rapamycin （2 mg-kg ·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 （Tern）, expression of interferon （IFN）-y, roTOR, and ribosomal protein $6 kinase （S6K）, and the levels of IL-6, IL- 10, galactomannan （GM）, and soluble TREM- 1 （sTREM-I） were measured. Results： Viable 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 ＋ I L- 12 group compared with the control, I PA （P = 0.01 ; P - 0.001 ）, and CTX ＋ 1PA （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 Tern, expression of IFN-y, and the level ofsTREM-I 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 roTOR pathway was blocked by rapamycin （P 〈 0.001）. Compared with the CTX ＋ I PA and CTX ＋ I PA ＋ RAPA groups, IL-12 treatment increased IL-6 and downregulated IL- 10 as well as G M, which strengthened the immune response to the IPA infection. Conclusions： mTOR 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.

T cell infiltration is associated with kidney injury in patients with anti-glomerular basement membrane disease

Cell-mediated autoimmunity, particularly that involving autoreactive T cells, participates in mediating anti-glomerular basement membrane(GBM) disease. However, direct kidney injury mediated by renal infiltrated T cells has not been clearly elucidated in humans. The T cell profile(CD3, CD4, CD8, IL-17, and foxp3) and macrophage(CD68) were examined by immunohistochemistry on renal biopsy tissues from 13 patients with anti-GBM disease. The correlation between cell infiltration and clinical data was also analyzed. We found that the distribution of T cell infiltration was predominant in the peri-glomerular and interstitial areas. CD3^+ T cell infiltratrion around the glomeruli with cellular crescent formations was significantly higher than that around the glomeruli with mild mesangial proliferation. CD8^+ T cells significantly accumulated around the glomeruli with cellular crescents without Ig G deposits compared to those with Ig G deposits. The prevalence of infiltrating CD8^+ T cells was correlated with the percentage of ruptured Bowman's capsules. In conclusion, cellular immunity may play a crucial role in the inflammatory kidney injury in anti-GBM patients. The periglomerular infiltration of T cells, especially CD8^+ T cells, may participate in the pathogenic mechanism of glomerular damage.