Cross-primed CD8+ cytotoxic T cells induce severe Helicobacter-associated gastritis in the absence of CD4+ T cells

BACKGROUND: Although previous studies have reported important roles of CD4(+) type 1-helper T cells and regulatory T cells in Helicobacter-associated gastritis, the significance of CD8(+) cytotoxic T cells remains unknown. To study the roles of CD8(+) T cells, we examined the immune response in the gastric mucosa of Helicobacter felis-infected major histocompatibility complex (MHC) class II-deficient (II(-/-)) mice, which lack CD4(+) T cells. MATERIALS AND METHODS: Stomachs from H. felis-infected wild-type and infected MHC II(-/-) mice were examined histologically and immunohistochemically. Gastric acidity and serum levels of anti-H. felis antibodies were measured. The expression of pro-inflammatory and anti-inflammatory cytokine, Fas-ligand, perforin, and Foxp3 genes in the gastric mucosa was investigated. RESULTS: H. felis-infected MHC II(-/-) mice developed severe gastritis, accompanied by marked infiltration of CD8(+) cells. At 1 and 2 months after inoculation, mucosal inflammation and atrophy were more severe in MHC II(-/-) mice, although gastritis had reached similar advanced stages at 3 months after inoculation. There was little infiltration of CD4(+) cells, and no Foxp3-positive cells were detected in the gastric mucosa of the infected MHC II(-/-) mice. The expression of the interleukin-1beta and Fas-ligand genes was up regulated, but that of Foxp3 was down regulated in the infected MHC II(-/-) mice. Serum levels of anti-H. felis antibodies were lower in the infected MHC II(-/-) mice, despite severe gastritis. CONCLUSIONS: The present study suggests that cross-primed CD8(+) cytotoxic T cells can induce severe H.-associated gastritis in the absence of CD4(+) helper T cells and that Foxp3-positive cells may have an important role in the control of gastric inflammation.     

Potentiating CD8+ T cell antitumor activity by inhibiting PCSK9 to promote LDLR-mediated TCR recycling and signaling

Metabolic regulation has been proven to play a critical role in T cell antitumor immunity.However,cholesterol metabolism as a key component of this regulation remains largely unexplored.Herein,we found that the low-density lipoprotein receptor (LDLR),which has been previously identified as a transporter for cholesterol,plays a pivotal role in regulating CD8+ T cell antitumor activity.Besides the involvement of cholesterol uptake which is mediated by LDLR in T cell priming and clonal expansion,we also found a non-canonical function of LDLR in CD8+ T cells: LDLR interacts with the T-cell receptor (TCR) complex and regulates TCR recycling and signaling,thus facilitating the effector function of cytotoxic T-lymphocytes (CTLs).Furthermore,we found that the tumor microenvironment (TME) downregulates CD8+ T cell LDLR level and TCR signaling via tumor cell-derived proprotein convertase subtilisin/kexin type 9 (PCSK9) which binds to LDLR and prevents the recycling of LDLR and TCR to the plasma membrane thus inhibits the effector function of CTLs.Moreover,genetic deletion or pharmacological inhibition of PCSK9 in tumor cells can enhance the antitumor activity of CD8+ T cells by alleviating the suppressive effect on CD8+ T cells and consequently inhibit tumor progression.While previously established as a hypercholesterolemia target,this study highlights PCSK9/LDLR as a potential target for cancer immunotherapy as well.     

Circulating CXCR5+CD4+ T cells assist in the survival and growth of primary diffuse large B cell lymphoma cells through interleukin 10 pathway

Diffuse large B cell lymphoma (DLBCL) is a common and aggressive cancer caused by the malignant transformation of B cells. Although it has been established that the follicular helper T (Tfh) cells play a central role in B cell development, little information is available on their involvement in DLBCL pathogenesis. We studied the role of the peripheral Tfh equivalent, the CXCR5⁺ CD4⁺ T cells, in DLBCL. Data showed that compared to CXCR5^- CD4⁺ T cells, CXCR5⁺ CD4⁺ T cells were significantly more effective at promoting the proliferation as well as inhibiting the apoptosis of primary autologous DLBCL tumor cells. Surprisingly, we found that at equal cell numbers, CXCR5⁺ CD4⁺ T cells in DLBCL patients secreted significantly less interleukin (IL)-21 than CXCR5^- CD4⁺ T cells, while the level of IL-10 secretion was significant elevated in the CXCR5⁺ compartment compared to the CXCR5^- compartment. Neutralization of IL-10 in the primary DLBCL-CXCR5⁺ CD4⁺ T cell coculture compromised the CXCR5⁺ CD4⁺ T cell-mediated pro-tumor effects, in a manner that was dependent on the concentration of anti-IL-10 antibodies. The CXCR5⁺ compartment also contained significantly lower frequencies of cytotoxic CD4⁺ T cells than the CXCR5^- compartment. In conclusion, our investigations discovered a previously unknown pro-tumor role of CXCR5-expressing circulating CD4⁺ T cells, which assisted the survival and proliferation of primary DLBCL cells through IL-10.     

Genetic approaches for the induction of a CD4+ T cell response in cancer immunotherapy

Recently, it has become more and more obvious that not only CD8+ cytotoxic T lymphocytes, but also CD4+ T helper cells are required for the induction of an optimal, long-lasting anti-tumor immune response. CD4+ T helper cells, and in particular IFN-gamma-secreting type 1 T helper cells, have been shown to fulfill a critical function in the mounting of a cancer-specific response. Consequently, targeting antigens into MHC class II molecules would greatly enhance the efficacy of an anti-cancer vaccine. The dissection of the MHC class II presentation pathway has paved the way for rational approaches to achieve this goal: novel systems have been developed to genetically manipulate the MHC class II presentation pathway. First, different genetic approaches have been used for the delivery of known epitopes into the MHC class II processing pathway or directly onto the peptide-binding groove of the MHC molecules. Second, several strategies exist for the targeting of whole tumor antigens, containing both MHC class I and class II restricted epitopes, to the MHC class II processing pathway. We review these data and describe how this knowledge is currently applied in vaccine development.     

CD8~+CD122~+T细胞在脑缺血过程中作用的研究

目的:探讨CD8+CD122+T细胞在脑缺血过程中的作用及其机制。方法:线栓法建立小鼠大脑中动脉栓塞模型(MCAO);激光共聚焦显微镜检测小鼠脑缺血组织中CD8+CD122+T细胞浸润情况;流式细胞仪检测脑缺血组织中CD8+CD122+T细胞/CD3+T细胞的比例及脾和胸腺中CD8+CD122+T细胞数量变化;RT-PCR方法检测CD8+CD122+T细胞对氧糖剥夺(Oxygen-glucose deprivation,OGD)条件下星形胶质细胞表达TNF-α,IL-1β,IFN-γ的影响。结果:各时间点脑缺血组织中均有CD8+CD122+T细胞浸润,且随脑缺血时间延长,缺血侧脑组织中CD8+CD122+T细胞/CD3+T细胞比例逐渐增加,5 d和7 d组差异显著,与非缺血侧相比,P5d0.05,P7d0.05;MCAO小鼠脾及胸腺中CD8+CD122+T细胞呈现先增高后降低的趋势。星形胶质细胞经OGD处理后,与对照组相比,IFN-γ、TNF-α、IL-1β表达显著增高,PIFN-γ0.01、PTNF-α0.001、PIL-1β0.01;CD122-blocked组与CD8+组相比,IFN-γ、TNF-α、IL-1β表达明显增高,PIFN-γ0.05、PTNF-α0.05、PIL-1β0.01;CD8+组与HBSS组相比,IFN-γ表达降低,P0.05;IL-1β表达有降低的趋势。结论:CD8+CD122+T细胞在脑缺血过程中发挥保护性作用,其保护作用通过CD122抑制星形胶质细胞TNF-α,IL-1β,IFN-γ炎症因子表达实现的。     

Ability of CD8(+) T cell anti-feline immunodeficiency virus activity correlated with peripheral CD4(+) T cell counts and plasma viremia

In the host defense mechanism against feline immunodeficiency virus (FIV) infection, CD8(+) T cells specifically attack virus-infected cells and suppress the replication of the virus in a non-cytolytic manner by secreting soluble factors. In this study, we measured CD8(+) T cell anti-FIV activity in 30 FIV-infected cats. We investigated its relationship with the number of peripheral blood lymphocytes, particularly the CD4(+) T cell and CD8(+) T cell counts, and the relationship between anti-FIV activity and the number of T cells of CD8alpha(+)beta(lo) and CD8alpha(+)beta(-) phenotypes. A clearly significant correlation was observed between anti-FIV activity and the number of CD4(+) T cells. A weaker anti-FIV activity was associated with a greater decrease in the number of CD4(+) T cells. However, there was no significant correlation between anti-FIV activity and the number of B or CD8(+) T cells. Compared with SPF cats, FIV-infected cats had significantly higher CD8alpha(+)beta(lo) T cell and CD8alpha(+)beta(-) T cell counts, but, no significant correlation was observed between these cell counts and anti-FIV activity. This anti-FIV activity significantly correlated with plasma viremia, which was detected in cats with a weak anti-FIV activity. These results suggest that the anti-FIV activity of CD8(+) T cells plays an important role in plasma viremia and the maintenance of CD4(+) T cells in the body. It is unlikely that CD8alpha(+)beta(lo) or CD8alpha(+)beta(-) T cells appearing after FIV infection represent a phenotype of CD8(+) cells with anti-FIV activity.     

Optimized DNA vaccines to specifically induce therapeutic CD8 T cell responses against autochthonous breast tumors

BACKGROUND: Vaccines capable of inducing CD8 T cell responses to antigens expressed by tumor cells are considered as attractive choices for the treatment and prevention of malignant diseases. Our group has previously reported that immunization with synthetic peptide corresponding to a CD8 T cell epitope derived from the rat neu (rNEU) oncogene administered together with a Toll-like receptor agonist as adjuvant, induced immune responses that translated into prophylactic and therapeutic benefit against autochthonous tumors in an animal model of breast cancer (BALB-neuT mice). DNA-based vaccines offer some advantages over peptide vaccines, such as the possibility of including multiple CD8 T cell epitopes in a single construct. MATERIALS AND METHODS: Plasmids encoding a fragment of rNEU were designed to elicit CD8 T cell responses but no antibody responses. We evaluated the use of the modified plasmids as DNA vaccines for their ability to generate effective CD8 T cell responses against breast tumors expressing rNEU. RESULTS: DNA-based vaccines using modified plasmids were very effective in specifically stimulating tumor-reactive CD8 T cell responses. Moreover, vaccination with the modified DNA plasmids resulted in significant anti-tumor effects that were mediated by CD8 T cells without the requirement of generating antibodies to the product of rNEU. CONCLUSIONS: DNA vaccination is a viable alternative to peptide vaccination to induce potent anti-tumor CD8 T cell responses that provide effective therapeutic benefit. These results bear importance for the design of DNA vaccines for the treatment and prevention of cancer.     

Emperipolesis mediated by CD8+ T cells correlates with biliary epithelia cell injury in primary biliary cholangitis

Primary biliary cholangitis (PBC) is an autoimmune disease characterized by chronic destruction of the bile ducts. A major unanswered question regarding the pathogenesis of PBC is the precise mechanisms of small bile duct injury. Emperipolesis is one of cell‐in‐cell structures that is a potential histological hallmark associated with chronic hepatitis B. This study aimed to clarify the pathogenesis and characteristics of emperipolesis in PBC liver injury. Sixty‐six PBC patients, diagnosed by liver biopsy combined with laboratory test, were divided into early‐stage PBC (stages I and II, n = 39) and late‐stage PBC (stages III and IV, n = 27). Emperipolesis was measured in liver sections stained with haematoxylin‐eosin. The expressions of CK19, CD3, CD4, CD8, CD20, Ki67 and apoptosis of BECs were evaluated by immunohistochemistry or immunofluorescence double labelling. Emperipolesis was observed in 62.1% of patients with PBC, and BECs were predominantly host cells. The number of infiltrating CD3⁺ and CD8⁺ T cells correlated with the advancement of emperipolesis (R² = 0.318, P < .001; R² = 0.060, P < .05). The cell numbers of TUNEL‐positive BECs and double staining for CK19 and Ki67 showed a significant positive correlation with emperipolesis degree (R² = 0.236, P < .001; R² = 0.267, P < .001). We conclude that emperipolesis mediated by CD8⁺ T cells appears to be relevant to apoptosis of BEC and thus may aggravate the further injury of interlobular bile ducts.     

HCV-specific interleukin-21+CD4+ T cells responses associated with viral control through the modulation of HCV-specific CD8+ T cells function in chronic hepatitis C patients

Interleukin-21 (IL-21)+CD4+ T cells are involved in the immune response against hepatitis B virus (HBV) by secreting IL-21. However, the role of IL-21+CD4+ T cells in the immune response against chronic hepatitis C (CHC) virus infection is poorly understood. This study aimed to investigate the role of IL-21+CD4+ T cells in CHC patients and the potential mechanisms. The study subjects included nineteen CHC patients who were grouped by viral load (low, < 10⁶ RNA copies/ml, n = 8; high, > 10⁶ RNA copies/ml, n = 11). The peripheral frequency of HCV-specific IL-21+CD4+ T cells was higher in the low viral load group and was negatively correlated with the serum HCV RNA viral load in all CHC patients. Meanwhile, IL-21+ cells accumulated in the liver in the low viral load group. In vitro, IL-21 treatment increased the expression of proliferation markers and cytolytic molecules on HCV-specific CD8+ T cells. In summary, these findings suggest that HCV-specific IL-21+CD4+ T cells might contribute to HCV control by rescuing HCV-specific CD8+ T cells in CHC patients.     

Altered frequency of CD8+CD11c+ T cells and expression of immunosuppressive molecules in lymphoid organs of mouse model of colorectal cancer

CD11c is a member of the β2-integrin family typically used to define myeloid dendritic cells (DCs). Recent reports identify CD11c-expressing CD8⁺ T cells as a new subset of CD8⁺ regulatory T cells (Treg). Evidence exists that CD11c⁺CD8⁺ T cells may exert their effector or regulatory functions under different conditions. To date, no studies have addressed the frequency of CD11c⁺ T cells in cancer. Limited evidence exists in terms of expression of immune-checkpoint receptors, programmed cell death protein 1 (PD-1) and T-lymphocyte-associated antigen 4 (CTLA-4), as well as forkhead box P3 (Foxp3) in mouse lymphoid organs. Here, we have assessed CD11c⁺CD8⁺ and CD11c⁺CD4⁺ T cells, Foxp3, PD-1, and CTLA-4 expressing CD4⁺ T cells and CD8⁺ T cells in different tissues from three groups of male BALB/c mice—young, mature, and those with colorectal cancer (CRC). Analysis of CD3⁺CD11c⁺ T cells in the bone marrow (BM), spleen, and lymph nodes (LN) in each group showed a higher percentage of CD3⁺CD11c⁺ T cells in the BM from all groups and in the lymphoid organs of the cancer group compared with the young and mature groups. CD4^low and CD4^high cell fractions in mice BM have different expression patterns for Foxp3 and CTLA-4. We have observed a higher frequency of CD8⁺PD-1⁺ T cells in the BM, spleen, and LN of CRC mice compared with normal mice. T-cell exhaustion is associated with inhibitory receptor PD-1. According to the regulatory roles of CD11c expression in CD8⁺ T cells, we have proposed that the elevated percentage of CD11c, Foxp3, CTLA-4, and PD-1 expressing T cells were associated with immune response dysregulation in CRC.     

Splenic dendritic cell subsets prime and boost CD8 T cells and are involved in the generation of effector CD8 T cells

The ability of the dendritic cell (DC) subsets, CD8alpha+ and CD8alpha- DCs, to initiate a CD8 T cell response or to activate memory CD8 T cells and generate effector CD8 T cells has been controversial. In this study, we analyse the capacity of splenic DC subsets to induce CD8 T cell responses to a CD8 T cell epitope (pb9) of a malaria antigen. The administration of peptide-pulsed CD8alpha- or CD8alpha+ DCs primes and boosts a primed CD8 T cell response against the malaria epitope. In vitro, depletion of CD11c(+) DCs from mouse splenocytes, immunised with recombinant vaccinia virus Ankara (MVA) expressing pb9 epitope, significantly reduced the generation of pb9-specific IFNgamma producing effector CD8 T cells, indicating that splenic DCs are involved in the development of pb9-specific IFNgamma producing effector cells. Taken together, this result shows that both DC subsets have the ability to prime and boost CD8 T cell responses and are involved in the activation of memory CD8 T cells.     

4-1BB costimulation enhances HSV-1-specific CD8+ T cell responses by the induction of CD11c+CD8+ T cells

Since 4-1BB plays a predominant role in CD8+ T cell responses, we investigated the effects of 4-1BB triggering on the primary and memory CD8+ T responses to HSV-1 infection. 4-1BB was detected on 10-15% of CD4+ and CD8+ T cells following the infection. 4-1BB-positive T cells were in the proliferative mode and showed the enhanced expression of anti-apoptotic proteins. Agonistic anti-4-1BB treatment exerted preferential expansion of CD8+ T cells and gB/H-2Kb-positive CD8+ T cells, and enhanced cytotoxicity against HSV-1 that was mainly mediated by CD11c+CD8+ T cells. CD11c+CD8+ T cells were re-expanded following re-challenge with HSV-1 at post-infection day 50, indicating that CD11c+CD8+ phenotype was maintained in memory CD8+ T cell pool. Our studies demonstrated that 4-1BB stimulation enhanced both primary and memory anti-HSV-1 CD8+ T cell responses, which was mediated by a massive expansion of antigen-specific CD11c+CD8+ T cells.     

Interaction between superantigen and T-cell receptor Vβ element determines levels of superantigen-dependent cell-mediated cytotoxicity of CD8+ T cells in induction and effector phases

Specific superantigens activate different T-cell fractions with distinct TCR Vβ elements in association with MHC class II molecules and also induce SDCC against MHC class II⁺ target cells. In the present study, to determine whether the responsiveness of each CD8⁺ T-cell fraction expressing a different TCR Vβ element is primarily determined by the TCR Vβ, we compared the levels of proliferation and SDCC in Vβ3⁺ and Vβ11⁺ T cells upon stimulation with SEA. Upon stimulation with SEA_wt, the levels of proliferation were higher in Vβ3⁺ T cells than in Vβ11⁺ T cells. The levels of SDCC were also higher for the combination of Vβ3⁺ T cells and SEA_wt than for the combination of Vβ11⁺ T cells and SEA_wt during both the induction phase and the effector phase. In addition, upon stimulation with SEA_m, the levels of proliferation were higher in Vβ11⁺ T cells than in Vβ3⁺ T cells. And then, the levels of SDCC were also higher for the combination of Vβ11⁺ T cells and SEA_m than for the combination of Vβ3⁺ T cells and SEA_m during both the induction phase and the effector phase. These results suggest that the SAG-responsiveness of each CD8⁺ T-cell fraction expressing a different TCR Vβ element is primarily determined by the interaction between the TCR Vβ element and the SAG.     

In vivo CD8+ T cell CRISPR screening reveals control by Fli1 in infection and cancer

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HIV-specific CD8+ T cell responses to HXB2 Gag and Nef peptide pools in Chinese HIV/AIDS patients

HXB2 is primarily used as a template strain in developing HIV vaccines in Europe and the US. However,it is not yet known whether the strain can induce strong HIV-specific CD8+ T cell responses in Chinese HIV/AIDS patients. In the present study,two groups of subjects were investigated:9 AIDS patients and 7 long-term nonprogressors (LTNPs). HIV-specific CD8+ T cell responses were examined in all patients through the ELISPOT assay. CD4+ T cell counts,CD8+ T cell counts,viral load and HIV subtype of each patien...     

Activation via TCR or IL-2 receptor of a CD8+ suppressor T cell clone: Effect on IL-10 production and on proliferation of the suppressor T cell

In a previous study, we established CD8⁺ suppressor T cell (Ts) clone 13G2 which produced the suppressive lymphokine, interleukin-10 (IL-10). In this study, we examined what physiological activator could induce both production of IL-10 from 13G2 and the proliferation of 13G2. Both the antigenic stimulation mimicked by the anti-CD3 antibody and the T cell growth factor interleukin-2 (IL-2) induced IL-10 production from the 13G2 clone equally well. 13G2 cells proliferated remarkably with IL-2 stimulation, while anti-CD3 only slightly induced proliferation of the clone. 13G2 cells also produced IL-10 in the presence of hydroxyurea which blocked transit of cells from G₁ to S phase. However, cycloheximide blocked the production of IL-10 from the Ts clone. The study demonstrates that both the anti-CD3 antibody and IL-2 induced IL-10 synthesis of the Ts clone equally well, and the proliferative response of Ts cells was induced more by IL-2 than by anti-CD3. IL-2 proved to be a good stimulator for Ts cells to produce suppressive lymphokine and to multiply their population.Abbreviation Ts suppressor T cell - Th helper T cell - Ag antigen - APC antigen presenting cell - IL interleukin - TCR T cell receptor - mAb monoclonal antibody     

CD8+T淋巴细胞与高血压心肌纤维化的研究进展

血管生长因子增多,血管平滑肌细胞增殖和炎症在血管重塑方面起到了关键的作用。这种低级的炎症反应导致粘附分子表达,白细胞的侵入,细胞因子的产生,氧化应激的增加,从而激活免疫细胞和血管炎症信号通路,使T淋巴细胞及巨噬细胞等细胞活化,产生和释放多种活性因子,激活心肌的细胞外基质生成细胞,引起胶原形成及代谢异常,并可导致心肌实质细胞的变性、坏死或亚细胞结构变化等,从而引起心肌纤维化一系列病理生理变化。本文主要就CD8+T淋巴细胞在高血压心肌纤维化炎症反应中的细胞毒性作用、诱导细胞凋亡作用、分泌大量的炎症因子、增加MMPs的活性从而影响心肌纤维化的形成等方面做一综述!     

Modulation of MOG 37-50-specific CD8+ T cell activation and expansion by CD43

Several recent reports have described an effector role for CD8(+) T cells during EAE. We have previously demonstrated reduced disease incidence and severity in CD43(-/-) mice following MOG immunization, and attributed this attenuation in disease progression to the effects of CD43 deficiency on CD4+ T cells. Here, we extend those studies to examine the effects of the loss of CD43 on MOG-specific CD8+ T cells. A reduced frequency of MOG-specific CD8+ T cells following immunization was observed in CD43(-/-) mice relative to wild-type controls, as demonstrated by intracellular cytokine and MHC tetramer staining. In addition, adoptive transfer of CD8+ MOG 35-55-primed LN cells from CD43(-/-) mice resulted in significantly attenuated EAE induction as compared to recipients of wild-type CD8+ MOG-primed cells. Analysis of intracellular signaling intermediates revealed a deficiency in the ability of MOG-specific CD8+ T cells to phosphorylate ERK in response to antigen. These results characterize an important role for CD43 during the activation and expansion of autoreactive MOG-specific CD8+ T cells.     

Faster cytotoxicity with age: Increased perforin and granzyme levels in cytotoxic CD8 + T cells boost cancer cell elimination

A variety of intrinsic and extrinsic factors contribute to the altered efficiency of CTLs in elderly organisms. In particular, the efficacy of antiviral CD8⁺ T cells responses in the elderly has come back into focus since the COVID‐19 pandemic outbreak. However, the exact molecular mechanisms leading to alterations in T cell function and the origin of the observed impairments have not been fully explored. Therefore, we investigated whether intrinsic changes affect the cytotoxic ability of CD8⁺ T cells in aging. We focused on the different subpopulations and time‐resolved quantification of cytotoxicity during tumor cell elimination. We report a surprising result: Killing kinetics of CD8⁺ T cells from elderly mice are much faster than those of CD8⁺ T cells from adult mice. This is true not only in the total CD8⁺ T cell population but also for their effector (T_EM) and central memory (T_CM) T cell subpopulations. TIRF experiments reveal that CD8⁺ T cells from elderly mice possess comparable numbers of fusion events per cell, but significantly increased numbers of cells with granule fusion. Analysis of the cytotoxic granule (CG) content shows significantly increased perforin and granzyme levels and turns CD8⁺ T cells of elderly mice into very efficient killers. This highlights the importance of distinguishing between cell‐intrinsic alterations and microenvironmental changes in elderly individuals. Our results also stress the importance of analyzing the dynamics of CTL cytotoxicity against cancer cells because, with a simple endpoint lysis analysis, cytotoxic differences could have easily been overlooked.