Site-specific accumulation of recently activated CD4+ Foxp3+ regulatory T cells following adoptive transfer

CD4(+) Foxp3(+) regulatory T (Treg) cells are required for the maintenance of self-tolerance, as demonstrated by profound autoimmunity in mice and humans with inactivating Foxp3 mutations. Recent studies demonstrate that Treg cells are anatomically compartmentalized within secondary lymphoid organs based on their TCR repertoire and specific organ-protective function; however, whether this reflects differential homing or in situ selection is not known. Here, using Foxp3-GFP reporter mice, we have examined the ability of polyclonal Treg cells from cervical LNs to return to their site-of-origin following adoptive transfer to nonlymphopenic congenic recipients. We find that bulk cervical LN Treg cells do not home directly to cervical LNs but rather accumulate site specifically over time following transfer. Site-specific enrichment is both more rapid and more pronounced among a population of recently activated (CD69(+) ) Treg cells. These data suggest that compartmentalization of Treg cells within secondary lymphoid organs may be governed by antigen recognition and implicate CD69 as a potential marker of recently activated Treg cells recognizing locally expressed antigens.     

Reactivity of naive CD4+CD25- T cells against gut microflora in healthy mice

We have previously shown that conventional as well as germ-free CD4+ T cells depleted of CD25+ cells from the gut-associated lymphoid tissue and the periphery proliferate specifically in response to enterobacterial antigen exposure whereas unfractionated CD4+ T cells are not reactive under these conditions. Here we show that the majority of the enteroantigen-specific CD4+ CD25- T cells are naive cells expressing a CD45RB high, CD62L high and CD44 low phenotype. These cells are also present in the thymus and data from adult thymectomized mice show that they represent late (>6 weeks) thymic emigrants. Upon enteroantigen activation, the CD4+ CD25- T cells secrete IL-4, IL-5, IL-10, granulocyte macrophage colony-stimulating factor, tumor necrosis factor-alpha and IFN-gamma. Clonotype mapping of the TCRBV regions 1-18 of enteroantigen-reactive CD4+ CD25- T cells by TCR clonotype mapping revealed the polyclonal nature of this subset. In conclusion, we have for the first time demonstrated the presence of an evolutionary, functionally conserved subset of CD4+ T cells, which are reactive against enterobacterial antigens. This subset resides both in the thymus and the periphery; it is not dependent on previous antigen experience and represents late thymic emigrants, which by enteroantigen-induced activation express a mixed Th 1-Th 2 phenotype. At homeostatic conditions, CD25+ T cells maintain peripheral tolerance in this CD4+ T cell subset.     

CD4+ T cells in sarcoidosis: targets and tools

Activated pulmonary T-helper type 1 lymphocytes are essential for the inflammatory process in sarcoidosis. Both the T cells and their mediators promoting inflammation may constitute possible targets for immunotherapy. A particular T-cell subset, the T-cell receptor AV2S3⁺ CD4⁺ T cells, are found at dramatically increased levels in the bronchoalveolar lavage fluid of a subpopulation of sarcoidosis patients with active disease. This particular T-cell subset may be used as a tool to reveal a sarcoidosis-specific antigen. Recent studies of natural killer T cells and T regulatory cells from patients with sarcoidosis have described abnormalities that may be relevant for the inflammatory process in this disease. These findings are exciting news and may be of help for designing new treatment strategies.     

CD4+CD25+调节性T细胞抑制小鼠自身免疫性甲状腺炎的发生

目的：研究CD4^ CD25^ Treg细胞对诱导小鼠实验性自身免疫性甲状腺炎(EAT)的影响。方法：磁性细胞分离器(MACS)分离CD4^ CD25^ T细胞，通过体外细胞增殖试验和IFN-γ的测定研究CD4^ CD25^ T细胞对CD4^ CD25^ T细胞的免疫抑制作用，同时通过过继转移试验研究CD4^ CD25^ T细胞抑制小鼠EAT的发生。结果：MACS分离的CD4^ CD25^ T细胞纯度可达到85％～94％，特异性表达FoxP3基因，体外能明显抑制效应性T细胞的增殖和IFN-γ的产生；将CD4^ CD25^ T细胞与病理性CD25^ T细胞共同注射正常小鼠，可抑制病理性T细胞诱导EAT的发生。结论：CD4^ CD25^ Treg细胞在体内外具有明显抑制效应性T细胞的功能。     

MHC class II-independent CD25+ CD4+ CD8alpha beta+ alpha beta T cells attenuate CD4+ T cell-induced transfer colitis

CD4+ alpha beta T cell populations that develop in mice deficient in MHC class II (through 'knockout' of either the Aalpha, or the Abeta chain of the I-A(b) molecule) comprise a major 'single-positive' (SP) CD4+ CD8- subset (60-90%) and a minor 'double-positive' (DP) CD4+ CD8alpha beta+ subset (10-40%). Many DP T cells found in spleen, mesenteric lymph nodes (MLN) and colonic lamina propria (cLP) express CD25, CD103 and Foxp3. Adoptive transfer of SP but not DP T cells from Aalpha(-/-) or Abeta(-/-) B6 mice into congenic RAG(-/-) hosts induces colitis. Transfer of SP T cells repopulates the host with only SP T cells; transfer of DP T cells repopulates the host with DP and SP T cells. Anti-CD25 antibody treatment of mice transplanted with DP T cells induces severe, lethal colitis; anti-CD25 antibody treatment of mice transplanted with SP T cells further aggravates the course of severe colitis. Hence, regulatory CD25+ T cells within (or developing from) the DP T cell population of MHC class II-deficient mice control the colitogenic potential of CD25- CD4+ T cells.     

Differential roles for CXCR3 in CD4+ and CD8+ T cell trafficking following viral infection of the CNS

Lymphocyte infiltration into the central nervous system (CNS) following viral infection represents an important component of host defense and is required for control of viral replication. However, the mechanisms governing inflammation in response to viral infection of the CNS are not well understood. Following intracranial (i.c.) infection of susceptible mice with mouse hepatitis virus (MHV), mice develop an acute encephalomyelitis followed by a chronic demyelinating disease. The CXC chemokine ligand 10 (CXCL10) is expressed following MHV infection and signals T cells to migrate into the CNS. The functional contribution of the CXCL10 receptor CXCR3 in host defense and disease in response to MHV infection was evaluated. The majority of CD4+ and CD8+ T cells infiltrating the CNS following MHV infection express CXCR3. Administration of anti-CXCR3 antibody reduced CD4+ T cell infiltration (p相似文献   

The CD2 and CD28 adhesion molecules induce long-term autocrine proliferation of CD4+ T cells

In vitro human T lymphocyte activation requires two-signal triggering delivered by lectins, phorbol esters or antibodies directed against surface molecules. Stimulation of adhesion molecules by CD2 and/or CD28 antibodies defines alternative activation pathways. Activation by CD2 + CD28 monoclonal antibodies induces high-level, long-lasting and monocyte-independent proliferation of highly purified T cells. Limiting dilution cultures showed that CD28 in association with CD2 or CD3, without addition of exogenous cytokines, induced single-cell proliferation. CD2 + CD28 stimulation induced long-term interleukin (IL)-2-dependent autocrine proliferation of CD4⁺ T cell clones. We tried to elucidate this long-term proliferation by evaluating cytokine secretion and cytokine dependency. CD28 associated to CD3 or CD2 induced high levels of IL-2, tumor necrosis factor (TNF) and IL-4 secretion for 10 days, in contrast to CD3 alone which induced only TNF secretion. Cytokines of the monocytic lineage were also secreted, such as colony-stimulating factor-1, granulocyte macrophage colony-stimulating factor or IL-1, the latter being more specific of CD2 + CD28 activation. Blocking antibodies confirmed the crucial role of IL-2 in CD2 + CD28 activation. Anti-IL-4, anti-IL-7 receptor or anti-TNF antibodies had no effect on proliferation. Stimulation with CD2 + CD28 induced long-term autocrine (at least for IL-2) proliferation for CD4⁺ T cells, with no evidence for the implication of another cytokine among those tested other than IL-2. This represents a model for long-term autocrine growth for non-leukemic cells.     

Regulation of CD4 T cells and their effects on immunopathological inflammation following viral infection

CD4 T cells help immune responses, but knowledge of how memory CD4 T cells are regulated and how they regulate adaptive immune responses and induce immunopathology is limited. Using adoptive transfer of virus‐specific CD4 T cells, we show that naive CD4 T cells undergo substantial expansion following infection, but can induce lethal T helper type 1‐driven inflammation. In contrast, memory CD4 T cells exhibit a biased proliferation of T follicular helper cell subsets and were able to improve adaptive immune responses in the context of minimal tissue damage. Our analyses revealed that type I interferon regulates the expansion of primary CD4 T cells, but does not seem to play a critical role in regulating the expansion of secondary CD4 T cells. Strikingly, blockade of type I interferon abrogated lethal inflammation by primary CD4 T cells following viral infection, despite that this treatment increased the numbers of primary CD4 T‐cell responses. Altogether, these data demonstrate important aspects of how primary and secondary CD4 T cells are regulated in vivo, and how they contribute to immune protection and immunopathology. These findings are important for rational vaccine design and for improving adoptive T‐cell therapies against persistent antigens.     

Recruitment of different subsets of antigen-presenting cells selectively modulates DNA vaccine-elicited CD4+ and CD8+ T lymphocyte responses

The immunogenicity of plasmid DNA vaccines may be limited by the availability of professional antigen-presenting cells (APC) at the site of inoculation. Here we demonstrate that the types of APC recruited to the injection site can selectively modulate CD4(+) or CD8(+) T lymphocyte responses elicited by an HIV-1 Env DNA vaccine in mice. Coadministration of plasmid GM-CSF with the DNA vaccine resulted in the recruitment of macrophages to the site of inoculation and specifically augmented vaccine-elicited CD4(+) T lymphocyte responses. In contrast, coadministration of plasmid MIP-1 alpha with the DNA vaccine resulted in the recruitment of dendritic cells to the injection site and enhanced vaccine-elicited CD8(+) T lymphocyte responses. Interestingly, coadministration of both plasmid GM-CSF and plasmid MIP-1 alpha with the DNA vaccine recruited both macrophages and dendritic cells and led to a synergistic and sustained augmentation of CD4(+)and CD8(+) T lymphocyte responses. These data demonstrate the critical importance of locally recruited professional APC in determining the magnitude and nature of immune responses elicited by plasmid DNA vaccines. Moreover, these studies show that different subsets of professional APC can selectively modulate DNA vaccine-elicited T lymphocyte responses.     

Interleukin-15 selectively expands CD57+ CD28- CD4+ T cells, which are increased in active rheumatoid arthritis

Proinflammatory cytokines as well as CD4(+) T cells play critical roles in the pathogenesis of rheumatoid arthritis (RA). Recently, an increase of CD57(+) or CD28(-)CD4(+) T cells was demonstrated in RA, although the mechanism of the increase of these T cells is unclear. In this study, we first examined the relationship between CD57(+)CD4(+) T cells and CD28(-)CD4(+) T cells and found CD57(+)CD28(-)CD4(+) T cells, but neither CD57(+)CD28(+) nor CD57(-)CD28(+) cells, expanded in the peripheral blood of active RA. In vitro experiments revealed that CD57(+)CD28(-)CD4(+) T cells selectively expanded in response to IL-15. Furthermore IL-15-stimulated CD57(+)CD28(-)CD4(+) T cells induced TNF-alpha production from monocytes. These results suggest that CD57(+)CD28(-)CD4(+) T cells are involved in the pathogenesis of RA by responding to IL-15.     

Human mucosal CD4+ T cells but not blood CD4+ T cells respond vigorously towards CD28 engagement

Human lamina propria T lymphocytes (LPT) possess functional properties profoundly different from those of peripheral blood T lymphocytes (PBT). While they are characterized by a low proliferative response to T cell receptor (TCR)/CD3 stimulation in vitro their responsiveness to activation through the 'co-stimulatory' CD2-receptor is enhanced when compared to PBT. In this study, we demonstrate that engagement of another co-stimulatory receptor on both LPT and PBT, namely CD28, by a single monoclonal antibody (mAb), respectively, strongly activates the former but not the latter through a PI3-kinase dependent signalling pathway leading to the production of inflammatory cytokines such as interleukin (IL)-2, tumour necrosis factor (TNF)-α, interferon (IFN)-γ and granulocyte-macrophage colony-stimulating factor (GM-CSF). In addition to the high sensitivity of LPT to CD2 stimulation, this finding supports the notion that 'non-specific/innate' mechanisms to activate T lymphocytes play a predominant role vis-à-vis'TCR driven/adaptive' responses in the intestinal mucosa. Furthermore, it suggests that results from preclinical tests for therapeutic antibodies performed with human blood derived T cells are probably insufficient to predict reactivities of tissue-resident immune cells, which--given their quantitative predominance--may critically determine the in-vivo response to such compounds.     

An increased frequency of autoantibody-inducing CD4+ T cells in pre-diseased lupus-prone mice

Pathogenic autoantibody production in murine models of lupus is dependent on autoreactive CD4+ helper T cells. However, the mechanisms which permit the selection and maintenance of this autoantibody-inducing CD4+ T-cell repertoire are currently unknown. We hypothesized that the peripheral CD4+ T-cell repertoire of lupus-prone mice was enriched with autoantibody-inducing specificities. To test this, we utilized the splenic focus assay to determine if pre-diseased lupus-prone (NZB x NZW)F(1) mice have an elevated frequency of autoreactive CD4+ T lymphocytes capable of supporting autoantibody production. The splenic focus limiting dilution assay permits anti-nuclear antibodies to be generated from contact-dependent T-B interactions in vitro. We show that young, pre-diseased lupus-prone mice have an elevated frequency of autoantibody-inducing CD4+ T cells. Interestingly, these autoantibody-inducing CD4+ T-cell responses are also present in the thymus. Therefore, an elevated frequency of autoantibody-inducing CD4+ T cells predisposes lupus-prone mice to the development of autoantibodies.     

Communication between human mast cells and CD4+ T cells through antigen‐dependent interactions

Mast cells (MCs) are immune cells residing in tissues where pathogens are first encountered. It has been indicated that MCs might also be involved in setting the outcome of T‐cell responses. However, little is known about the capacity of human MCs to express MHC class II and/or to capture and present antigens to CD4⁺ T cells. To study the T‐cell stimulatory potential of human MCs, CD34⁺ stem cell derived MCs were generated. These cells expressed HLA‐DR when stimulated with IFN‐γ, and, importantly, presented peptide and protein for activation of antigen‐specific CD4⁺ T cells. The interplay between MC and T cell led to increased HLA‐DR expression on MCs. MCs were present in close proximity to T cells in tonsil and expressed HLA‐DR and CD80, indicating their ability to present antigens to CD4⁺ T cells in T‐cell areas of human LNs. Our data show that MCs can present native antigens to human CD4⁺ T cells and that HLA‐DR expressing MCs are present in tonsil tissue, indicating that human MCs can directly activate T cells and provide a rationale to study the potential of MCs to prime and/or skew human T‐cell responses.     

FoxP3 mRNA splice forms in synovial CD4+ T cells in rheumatoid arthritis and psoriatic arthritis

Our aim was to elucidate the relative amount of the different splice forms of FoxP3 mRNA in CD4+ T cells in peripheral blood (PB) compared to synovial fluid (SF) in RA and PsA patients. FoxP3 mRNA was measured using a quantitative real-time PCR method. CD4+ T cells were isolated from 17 paired samples of PB and SF from RA and PsA patients, and PB from 10 controls. FoxP3fl and FoxP3Δ2 mRNA was significantly increased (6.7 and 2.1-fold, respectively) in PB CD4+ T cells from RA patients compared to controls. FoxP3fl and Δ2 mRNA in SF CD4+ T cells was increased compared to controls in sero-negative RA and PsA, but not in sero-positive RA patients, who had a high FoxP3 expression in both PB and SF. The FoxP3Δ2Δ7 mRNA was barely detectable in patient samples, and not at all in healthy individuals. We provide evidence of an increased expression of FoxP3 splice forms in synovial CD4+ T cells from RA patients. A skewed, high expression profile of FoxP3, but not CTLA-4, in sero-negative RA and PsA, indicates that synovial CD4+ T cells may represent unique subsets of T cells which have been induced locally or selectively recruited to the joint.     

The life (and death) of CD4+CD28null T cells in inflammatory diseases

Inflammation contributes to the development and perpetuation of several disorders and T lymphocytes orchestrate the inflammatory immune response. Although the role of T cells in inflammation is widely recognized, specific therapies that tackle inflammatory networks in disease are yet to be developed. CD4⁺CD28^null T cells are a unique subset of helper T lymphocytes that recently shot back into the limelight as potential catalysts of inflammation in several inflammatory disorders such as autoimmunity, atherosclerosis and chronic viral infections. In contrast to conventional helper T cells, CD4⁺CD28^null T cells have an inbuilt ability to release inflammatory cytokines and cytotoxic molecules that can damage tissues and amplify inflammatory pathways. It comes as no surprise that patients who have high numbers of these cells have more severe disease and poor prognosis. In this review, I provide an overview on the latest advances in the biology of CD4⁺CD28^null T cells. Understanding the complex functions and dynamics of CD4⁺CD28^null T cells may open new avenues for therapeutic intervention to prevent progression of inflammatory diseases.     

CD38+ CD45RBlow CD4+ T cells: a population of T cells with immune regulatory activities in vitro

An antibody reactive with CD38 revealed both phenotypic and functional heterogeneity amongst CD45RB^low cells. Functional analysis of the CD38⁺ and CD38⁻ fractions showed that the latter contained T cells which responded to recall antigens and produced high levels of cytokine in response to polyclonal stimulation. In contrast, the CD38⁺ population failed to proliferate or to produce detectable levels of cytokines. Despite appearing unresponsive, the CD38⁺ population significantly inhibited anti-CD3-induced proliferation and cytokine secretion by the reciprocal CD38⁻ population. Immune suppression required stimulation through the TCR and was dependent on a physical interaction between regulatory and responding CD4⁺ populations. It did not involve killing of the responding T cells or secretion of IL-10 or TGF-β. Despite some similarities there is no direct correlation between the in vitro suppression characteristic of the CD38⁺ CD45RB^low subset and in vivo suppression which has been shown to be mediated by unseparated CD45RB^low CD4⁺ T cells. However, these results demonstrate that two functionally distinct subsets of T cells reside within the antigen-exposed or CD45RB^low CD4⁺ T cell population and are thus generated in vivo: (1) conventional memory T cells which proliferate and secrete cytokines in response to activation and (2) a population of regulatory T cells which inhibit T cell activation in vitro. Antibodies reactive with CD38 may provide a useful tool with which to study the role of these T cell subsets in the induction and regulation of the immune response.     

Determination of cell expansion and surface molecule expression on anti‐CD3/28 expanded CD4+ T cells

CD4⁺ T cell immunotherapy has potential for treatment in HIV‐infected patients. A large number of expanded CD4⁺ T cells and confirmation of functional‐related phenotypes are required for ensuring the successful outcomes of treatment. Freshly isolated CD4⁺ T cells from healthy donors were activated with anti‐CD3/28‐coated magnetic beads at different bead‐to‐cell ratios and cultured in the absence and presence of IL‐2 supplementation for 3 weeks. Fold expansion, cell viability, growth kinetic and lymphocyte subset identities were determined. Data demonstrated that a 1:1 bead‐to‐cell ratio rendered the highest expansion of 1044‐fold with 88% viability and 99.5% purity followed by the 2:1 and 0.5:1 ratios. No significant difference in proliferation and phenotypes was found between non–IL‐2 and IL‐2 supplementation groups. Several specific surface molecule expressions of the expanded cells including chemokine receptors, adhesion molecules, co‐stimulatory molecules, activation molecules, maturation markers, cytokine receptors and other molecules were altered when compared to the unexpanded cells. This optimized expansion protocol using the 1:1 bead‐to‐cell ratio of anti‐CD3/28‐coated magnetic beads and culture condition without IL‐2 supplementation provided the satisfactory yield with good reproducibility. Specific surface molecule expressions of the expanded cells presented potential roles in proliferation, differentiation, homeostasis, apoptosis and organ homing.     

癌灶CD4~+CD25~+和CD8~+ T细胞亚群与卵巢浆液性癌患者生存期相关

检测卵巢浆液性癌患者癌组织中CD4+CD25+及CD8+T细胞的数目,探讨其两种T细胞介导的免疫功能对疾病发展及预后的影响。免疫组织化学双标及单标的染色方法检测41例卵巢浆液性癌患者手术切除癌组织标本中CD4+CD25+和CD8+T细胞的数目。结果显示,癌灶中CD4+CD25+T淋巴细胞为(19.95±11.50)个/10HPF,CD8+T淋巴细胞为(43.46±16.69)个/10HPF。生存分析发现高CD4+CD25+T细胞组患者总生存期较低CD4+CD25+T细胞组缩短,差异有显著性(P<0.05);而高CD8+T细胞组患者总生存期与低CD8+T细胞组相比延长,且差异有显著性(P<0.05),此外两种T细胞数目与患者年龄、病理分级、临床分期、腹水细胞学及淋巴结转移等临床病理因素均无关(P>0.05)。结果表明,卵巢浆液性癌中高CD4+CD25+T细胞提示患者预后不良,可能与CD4+CD25+T细胞介导的免疫抑制导致肿瘤免疫逃逸有关;癌组织中高CD8+T细胞提示患者预后较好,两种T细胞对卵巢浆液性癌预后的评估有重要的价值,同时可以通过阻断CD4+CD25+T细胞的免疫抑制作用改善卵巢浆液性癌患者的预后,为卵巢癌治疗提供靶目标。     

CD4+CD25+T调节细胞的研究进展

CD4 CD25 TH细胞通过抗原特异性方式或细胞接触的方式抑制自身反应性T细胞的活化,能有效地维持自身免疫耐受,是调节自身反应性T细胞和防止自身免疫病发生的重要调节细胞。