Showing papers in "International Immunology in 2007"
TL;DR: The history ofPD-1 research since its discovery and recent findings that suggest promising future for the clinical application of PD-1 agonists and antagonists to various human diseases are summarized.
Abstract: Programmed cell death-1 (PD-1, Pdcd1), an immunoreceptor belonging to the CD28/CTLA-4 family negatively regulates antigen receptor signaling by recruiting protein tyrosine phosphatase, SHP-2 upon interacting with either of two ligands, PD-L1 or PD-L2. Because of the wide range of ligand distribution in the body, its biological significance pervades almost every aspect of immune responses including autoimmunity, tumor immunity, infectious immunity, transplantation immunity, allergy and immunological privilege. In this review, we would like to summarize the history of PD-1 research since its discovery and recent findings that suggest promising future for the clinical application of PD-1 agonists and antagonists to various human diseases.
1,100 citations
TL;DR: Ex vivo expression of FOXP3 is a normal consequence of CD4(+) T cell activation and, in humans, it can no longer be used as an exclusive marker of nTregs.
Abstract: Forkhead box P3 (FOXP3) is currently thought to be the most specific marker for naturally occurring CD4 1 CD25 1 T regulatory cells (nTregs). In mice, expression of FoxP3 is strictly correlated with regulatory activity, whereas increasing evidence suggests that in humans, activated T effector cells (Teffs) may also express FOXP3. In order to better define the role of FOXP3 in human Teff cells, we investigated the intensity and kinetics of expression in ex vivo Teff cells, suppressed Teff cells and Teff cell lines. We found that all dividing Teff cells expressed FOXP3, but only transiently, and at levels that were significantly lower than those in suppressive nTregs. This temporary expression in Teff cells was insufficient to suppress expression of reported targets of FOXP3 repressor activity, including CD127, IL-2 and IFN-g, and was not correlated with induction of a nTreg phenotype. Thus expression of FOXP3 is a normal consequence of CD4 1 T cell activation and, in humans, it can no longer be used as an exclusive marker of nTregs. These data indicate that our current understanding of how FOXP3 contributes to immune tolerance in humans needs to be re-evaluated.
841 citations
TL;DR: Kinetic analysis of cytokine secretion demonstrated that PD-1 blockade increased both type-1 and type-2 cytokine accumulation in culture without any apparent skewing of the cytokine repertoire, suggesting increased recognition efficiency for cognate peptide.
Abstract: Negative co-stimulatory signaling mediated via cell surface programmed death (PD)-1 expression modulates T and B cell activation and is involved in maintaining peripheral tolerance. In this study, we examined the effects of a fully human PD-1-abrogating antibody on the in vitro expansion and function of human vaccine-induced CD81 T cells (CTLs) specific for the melanoma-associated antigens glycoprotein 100 (gp100) and melanoma antigen recognized by T cells (MART)-1. PD-1 blockade during peptide stimulation augmented the absolute numbers of CD31, CD41, CD81 and gp100/MART-1 MHC:peptide tetramer1 CTLs. This correlated with increased frequencies of IFN-gsecreting antigen-specific cells and augmented lysis of gp1001/MART-11 melanoma targets. PD-1 blockade also increased the fraction of antigen-specific CTLs that recognized melanoma targets by degranulation, suggesting increased recognition efficiency for cognate peptide. The increased frequencies and absolute numbers of antigen-specific CTLs by PD-1 blockade resulted from augmented proliferation, not decreased apoptosis. Kinetic analysis of cytokine secretion demonstrated that PD-1 blockade increased both type-1 and type-2 cytokine accumulation in culture without any apparent skewing of the cytokine repertoire. These findings have implications for developing new cancer immunotherapy strategies.
262 citations
TL;DR: It is concluded that IL-6 acts directly to promote the development of Th17 by activating the T cell gp130-STAT3 pathway but has a minimum effect on Treg development at least in the steady state in vivo.
Abstract: IL-17-producing Th (Th17) comprise a distinct lineage of pro-inflammatory Th that are major contributors to autoimmune diseases. Treatment with IL-6 and transforming growth factor beta (TGFbeta) induces naive CD4+ T cells to generate Th17, which also requires expression of the IL-6/TGFbeta target RORgammat. We reported that IL-6 transduces two signaling pathways via tyrosine redidues of the signal transducer gp130: one depends on signal transducers and activators of transcription (STAT)-3 activation and the other on Src homology region 2 domain-containing phosphatase 2 (SHP2)/Grb2 associated binder (Gab)/mitogen-activated protein kinase (MAPK) activation. Here, we showed that CD4+ T cells carrying a mutant gp130 that transduces the SHP2/Gab/MAPK pathway but not the STAT3-mediated one failed to develop into Th17, while CD4+ T cells whose mutant gp130 transduces the STAT3 signal only generated Th17, indicating that IL-6 acts directly on T cells through the tyrosine residues of gp130 required for STAT3 activation to promote the development of Th17. Moreover, we found that gp130-STAT3 pathway is essential for Th17 development and for the expression of RORgammat by using T cells specifically lacking gp130 and STAT3. Noteworthy is that the regulatory T cell (Treg) percentages and numbers were comparable between all mutant mice we tested in vivo, although we showed that IL-6-gp130-STAT3 pathway suppressed Treg development in vitro. Thus, we conclude that IL-6 acts directly to promote the development of Th17 by activating the T cell gp130-STAT3 pathway but has a minimum effect on Treg development at least in the steady state in vivo. Therefore, blockade of IL-6-gp130-STAT3 pathway in CD4+ T cells could be a good target for controlling unwanted Th17-mediated immune responses including autoimmune diseases.
243 citations
TL;DR: It is demonstrated that E2 can affect multiple regulatory elements that influence Treg suppression, including both PD-1-dependent and PD- 1-independent pathways, and functional suppression was still enhanced by E2 pre-treatment in the absence ofPD-1.
Abstract: Estrogen [17-b-estradiol (E2)] is a potent driver of the FoxP3+ regulatory T cell (Treg) compartment. Recently, Tregs were further characterized by intracellular expression of the negative co-stimulatory molecule, programmed death-1 (PD-1). To clarify the role of PD-1 versus FoxP3 in E2-enhanced Treg suppression, we evaluated both markers and functional suppression in wild-type, estrogen receptor knockout (ERKO) mice and PD-1 KO mice. We demonstrate that intracellular PD-1 expression is also E2 sensitive, since E2 treatment increased intracellular PD-1 levels in CD4+FoxP3+ cells, and PD-1 expression and Treg suppression were reduced in ERKO mice. Surprisingly, PD-1 KO mice retained normal levels of FoxP3 expression, but Tregs from these mice lacked functional suppression. However, E2 pre-treatment of PD-1 KO mice partially restored functional Treg suppression without enhancing FoxP3 expression. Thus, functional Treg suppression in immunized mice without E2 pretreatment was more closely linked to PD-1 expression than to FoxP3 expression. However, although enhanced PD-1 expression was E2 dependent, functional suppression was still enhanced by E2 pretreatment in the absence of PD-1. These data clearly demonstrate that E2 can affect multiple regulatory elements that influence Treg suppression, including both PD-1-dependent and PD-1independent pathways.
196 citations
TL;DR: Data indicate that progesterone directly inhibits mature rat BMDC capacity to drive pro-inflammatory responses, which could contribute to or account for some of the differential expression of autoimmune/inflammatory disease in females.
Abstract: A variety of extraimmune system factors, including hormones, play a critical role in regulating immunity. Progesterone has been shown to affect immunity in rodents and humans, mainly at concentrations commensurate with pregnancy. These effects are primarily mediated via the progesterone receptor (PR), which acts as a transcription factor, although non-genomic effects of PR activation have been reported. In this study, we evaluated the effects of progesterone on rat dendritic cells (DCs) at ranges encompassing physiologic and pharmacologic concentrations to determine whether progesterone plays a role in modulating DC-mediated immune responses. DCs were derived by culturing rat bone marrow cells in granulocyte macrophage colony-stimulating factor and IL-4. Cells were analyzed for expression of PR using FACS analysis, real-time reverse transcriptase-PCR and fluorescent microscopy. Progesterone treatment of LPS-activated, mature bone marrow-derived dendritic cells (BMDCs) suppressed production of the pro-inflammatory response-promoting cytokines tumor necrosis factor-alpha and IL-1beta in a dose-dependent manner but did not affect production of the pro-inflammatory response-inhibiting cytokine IL-10. Treatment of cells with progesterone also resulted in down-regulation of co-stimulatory molecule CD80 and MHC class II molecule RT1B expression. In addition, progesterone inhibited DC-stimulated proliferation of T cells. Suppression of pro-inflammatory response-promoting cytokine production by progesterone was prevented using the PR antagonist RU486. There was no dose-dependent effect of progesterone treatment on immature DC capacity to take up antigenic peptide. These data indicate that progesterone directly inhibits mature rat BMDC capacity to drive pro-inflammatory responses. This mechanism could contribute to or account for some of the differential expression of autoimmune/inflammatory disease in females.
146 citations
TL;DR: This study explains some features of the pathogenesis of a disease syndrome that arises as a consequence of specific assembly failure of a transcriptional repressor due to certain mutations within the FOXP3 leucine zipper.
Abstract: We have found that FOXP3 is an oligomeric component of a large supramolecular complex. Certain FOXP3 mutants with single amino acid deletions in the leucine zipper domain of FOXP3 are associated with the X-linked autoimmunity-allergic dysregulation (XLAAD) and immunodysregulation, polyendocrinopathy and enteropathy, X-linked (IPEX) syndrome in humans. We report that the single amino acid deletion found in human XLAAD/IPEX patients within the leucine zipper domain of FOXP3 does not disrupt its ability to join the larger protein complex, but eliminates FOXP3 homooligomerization as well as heteromerization with FOXP1. We found that the zinc finger‐leucine zipper domain region of FOXP3 is sufficient to mediate both homodimerization and homotetramerization. However, the same domain region from XLAAD/IPEX FOXP3 containing an E251 deletion prevents oligomerizaton and the protein remains monomeric. We also found that wild-type FOXP3 directly binds to the human IL-2 promoter, but the E251 deletion in FOXP3 in XLAAD/IPEX patient’s T cells disrupts its association with the IL-2 promoter in vivo and in vitro, and limits repression of IL-2 transcription after T-cell activation. Our results suggest that compromising FOXP3 homo-oligomerization and heterooligomerization with the FOXP1 protein impairs DNA-binding properties leading to distinct biochemical phenotypes in humans with the XLAAD/IPEX autoimmune syndrome. This study explains some features of the pathogenesis of a disease syndrome that arises as a consequence of specific assembly failure of a transcriptional repressor due to certain mutations within the FOXP3 leucine zipper.
129 citations
TL;DR: CD27-CD70 interactions may promote Th1 formation by permitting naive T cells to respond to differentiation signals and by promoting survival of activated effector T cells.
Abstract: Stimulation of CD27, a member of the tumour necrosis factor receptor family, by its ligand CD70 induces expansion of IFNg secreting CD4 1 and CD8 1 T cells in vivo. We here analysed the
128 citations
TL;DR: It is found that IL-2 maintains optimal function of human CD4+ CD25+ Tregs in vitro and increases expression of both forkhead box protein 3, human nomenclature (FOXP3) and the distinctive markers CD25, cytotoxic T lymphocyte antigen-4 (CTLA-4) and glucocorticoid-induced tumor necrosis factor receptor superfamily member number 18 (GITR).
Abstract: CD4+ CD25+ regulatory T cells (Tregs) have far-reaching immunotherapeutic applications, the realization of which will require a greater understanding of the factors influencing their function and phenotype during ex vivo manipulation. In murine models, IL-2 plays an important role in both the maintenance of a functional Treg population in vivo and the activation of suppression in vitro. We have found that IL-2 maintains optimal function of human CD4+ CD25+ Tregs in vitro and increases expression of both forkhead box protein 3, human nomenclature (FOXP3) and the distinctive markers CD25, cytotoxic T lymphocyte antigen-4 (CTLA-4) and glucocorticoid-induced tumor necrosis factor receptor superfamily member number 18 (GITR). Although IL-2 reduced spontaneous apoptosis of Tregs, this property alone could not account for the optimal maintenance of the regulatory phenotype. The inhibition of phosphatidylinositol 3-kinase (PI3K) signaling by LY294002, a chemical inhibitor of PI3K, abolished the maintenance of maximal suppressive potency by IL-2, yet had no effect on the up-regulation of FOXP3, CD25, CTLA-4 and GITR. Other common gamma chain (gammac) cytokines-IL-4, IL-7 and IL-15-had similar properties, although IL-4 showed a unique lack of effect on the expression of FOXP3 or Treg markers despite maintaining maximal regulatory function. Taken together, our data suggest a model in which the gammac cytokines IL-2, IL-4, IL-7 and IL-15 maintain the optimal regulatory function of human CD4+ CD25+ T cells in a PI3K-dependent manner, offering new insight into the effective manipulation of Tregs ex vivo.
114 citations
TL;DR: This study contributes to a better understanding of the inflammatory processes induced by an encapsulated pathogen and suggests that the relative expression of CPS, known to be modulated during bacterial invasion and dissemination in the host, might alter interactions with host cells and, consequently, the outcome of theinflammatory response.
Abstract: Streptococcus suis capsular type 2 is an important swine pathogen and an agent of zoonosis. Although meningitis is the most common form of disease, septicemia and septic shock are also frequently reported. Despite reports that CD14 is involved in the recognition of encapsulated S. suis by host cells, the mechanisms underlying exacerbated release of pro-inflammatory cytokines, which may have a negative impact on disease outcome, are unclear. Here, we demonstrated that stimulation of human monocytes by whole encapsulated S. suis or its purified cell wall components influences the relative expression of Toll-like receptor (TLR)-2 and CD14 mRNA. Moreover, this stimulation triggered the release of cytokines (tumor necrosis factor-a ,I L-1 b and IL-6) and chemokines (IL-8 and monocyte chemoattractant protein-1), which was significantly reduced by antibody-mediated blocking of TLR2 but not TLR4. Mouse macrophages deficient in TLR2 also showed impaired cytokine responses to encapsulated bacteria. Given that this response was completely abrogated in myeloid differentiation factor 88 (MyD88)-deficient macrophages, other TLRs might also be involved. Furthermore, we demonstrated that the presence of capsular polysaccharide (CPS)-modulated S. suis interactions with TLRs. In the absence of CPS, uncovered cell wall components induced cytokine and chemokine production via TLR2-dependent as well as -independent pathways, whereas CPS contributes to MCP-1 production in a MyD88-independent manner. Overall, this study contributes to a better understanding of the inflammatory processes induced by an encapsulated pathogen and suggests that the relative expression of CPS, known to be modulated during bacterial invasion and dissemination in the host, might alter interactions with host cells and, consequently, the outcome of the inflammatory response.
110 citations
TL;DR: KLRG1 may differentially regulate NK cell and T cell functions through the association with different ligands as well as the recruitment of distinct phosphatases, and it is demonstrated that K LRG1 engagement can inhibit sub-optimal TCR signaling.
Abstract: The killer cell lectin-like receptor G1 (KLRG1) is a unique inhibitory receptor expressed on a phenotypically mature subset of resting NK cells as well as subsets of T cells in naive mice. In vivo, pathogenic immune system activation induces dramatic changes in the expression patterns of KLRG1 among the different cell subsets. In order to enhance our understanding of KLRG1 signaling properties and to clarify the functions of KLRG1 on these cells, we identified the broadly expressed N-cadherin molecule as a ligand for KLRG1. We further demonstrate that a second member of this superfamily of adhesion molecules, E-cadherin, binds to KLRG1. Additionally, we show that upon phosphorylation of the immunoreceptor tyrosine-based inhibitory motif (ITIM) tyrosine, KLRG1 recruits both SHIP-1 and SHP-2 but not SHP-1. We also delineate the key KLRG1 ITIM amino acid residues required for optimal association with these phosphatases. Finally, we demonstrate that KLRG1 engagement can inhibit sub-optimal TCR signaling. Taken together, our results indicate that KLRG1 may differentially regulate NK cell and T cell functions through the association with different ligands as well as the recruitment of distinct phosphatases.
TL;DR: It is concluded that aging does not impair recruitment of LPCs to the thymus, but is characterized by abnormalities in thymic epithelial architecture, especially medullary TEC function that may provide sub-optimal support forThymic development of L PCs.
Abstract: Aging is associated with reduced numbers of all thymocyte sub-populations, including early T-cell progenitors. However, it is unclear if this is due to inadequate recruitment of lymphohematopoietic progenitor cells (LPCs) to the aged thymus or to abnormal development of T cells within the thymus. We found that LPCs from young mice were recruited equally well to the thymi of young or aged mice and that thymic stromal cells (TSCs) from young and old mice expressed similar levels of P-selectin and CCL25, which are believed to mediate recruitment of LPCs to the adult thymus. However, the number of recruited thymocytes in old thymus was markedly reduced after two weeks, indicating that T-cell development or proliferation is defective in the aged thymus. We also found that LPCs from aged and young mice have similar capacities to seed a fetal thymus that was transplanted under the kidney capsule. Thymic epithelial cells (TECs) in aged mice had lower proliferative capacity and higher rate of apoptosis, compared with findings in young animals. In addition, immunofluorescence staining with antibodies to cortical and medullary TECs revealed that aged thymi had a disorganized thymic stromal architecture, combined with reduced cellularity of the medulla, and apoptosis of thymocyte sub-populations in the medullary microenvironment was increased, compared with that in young mice. We conclude that aging does not impair recruitment of LPCs to the thymus, but is characterized by abnormalities in thymic epithelial architecture, especially medullary TEC function that may provide sub-optimal support for thymic development of LPCs.
TL;DR: It is demonstrated that human DCs exposed to different strains of gut-derived LAB consistently induce proliferation, cytotoxicity and activation markers in autologous NK cells, and therefore LAB modulating IFN-gamma production in NK cells may be important regulators of the immune response.
Abstract: Lactic acid bacteria (LAB) are abundant in the gastrointestinal tract where they continuously regulate the immune system. NK cells are potently activated by dendritic cells (DCs) matured by inflammatory stimuli, and NK cells are present in the gut epithelium and in mesenteric lymph nodes, but it is not known how NK-DC interactions are affected by the predominantly non-pathogenic LAB. We demonstrate that human DCs exposed to different strains of gut-derived LAB consistently induce proliferation, cytotoxicity and activation markers in autologous NK cells. On the contrary, strains of LAB differ greatly in their ability to induce DC-dependent IFN-gamma production by NK cells. This suggests that DCs stimulated by gut LAB may expand the pool of NK cells and increase their cytotoxic potential. Specific LAB, inducing high levels of IL-12 in DCs, may promote amplification of a type-1 response via potent stimulation of IFN-gamma production in NK cells. Combining IFN-gamma-inducing and non-inducing LAB completely abrogates DC-mediated IFN-gamma production by NK cells, and therefore LAB modulating IFN-gamma production in NK cells may be important regulators of the immune response.
TL;DR: It is found that purified polysaccharides from GL mycelium could induce human PBMC proliferation and phenotypic and functional maturation of DCs with significant IL-12 and IL-10 production, and poly Saccharides of different sources have different immune potency and effect on human immune cells including DCs.
Abstract: Polysaccharides derived from fungi and plants have been increasingly used as dietary supplement with therapeutic intention for cancer. However, whether these polysaccharides from different sources and structures can elicit similar immunological effects remain unknown. This study aims to investigate and compare the effects of selected groups of purified and crude polysaccharides on human dendritic cells (DCs), the most potent antigen-presenting cells. The selected polysaccharides were from Ganoderma lucidum [(GL) Lingzhi, Reishi], a medicinal mushroom commonly used by oriental; and barley glucan, a purified polysaccharide with known in vivo immunomodulating effect. We found that purified polysaccharides from GL mycelium could induce human PBMC proliferation and phenotypic and functional maturation of DCs with significant IL-12 and IL-10 production. Polysaccharides of GL spore and barley were both rather weak immunostimulator in vitro. In general, all these polysaccharides did not polarize T cells into either T(h)1 or T(h)2 or regulatory T cells, except for crude spore polysaccharides-treated DCs which could suppress T cell proliferation with IL-10 production. This study revealed the polysaccharides of different sources have different immune potency and effect on human immune cells including DCs. Our study also provides a reproducible biological platform for comparing the potential therapeutic effects of different herbal-derived polysaccharides in the future.
TL;DR: Dok-1 and Dok-2 play an essential role in the negative regulation of TCR signaling by an as yet unidentified mechanism, and all mice lacking these proteins exhibited elevated titers of antibodies to double-stranded DNA and developed lupus-like renal disease.
Abstract: Interaction of the TCR complex with self- or foreign peptides is a central event in the immune responses. Upon TCR stimulation, a protein–tyrosine kinase (PTK), ZAP-70, is recruited to signaling units of the TCR complex, such as TCRz, to play an essential role in T cell activation. Here, we find that mice lacking adaptor proteins Dok-1 and Dok-2 show augmented responses to thymus-dependent, but not thymus-independent, antigens, and that their T cells show elevated responses to TCR stimulation, including the activation of ZAP-70 and subsequent proliferation and cytokine production. Furthermore, the forced expression of Dok-1 or Dok-2 in a CD3 1 CD4 1 T cell clone inhibited the activation of ZAP-70 upon TCR stimulation. Interestingly, the Dok-1 and Dok-2 COOH-terminal moieties bearing the src homology 2 target motifs were dispensable for this negative regulation, even though they are crucial for the known adaptor function of Dok-family proteins. Thus, by an as yet unidentified mechanism, Dok-1 and Dok-2 play an essential role in the negative regulation of TCR signaling. Consistently, all mice lacking these proteins exhibited elevated titers of antibodies to double-stranded DNA and developed lupus-like renal disease.
TL;DR: It is found that HMBPP is the major Vg2Vd2 T-cell antigen for many bacteria, including Mycobacterium tuberculosis, Yersinia enterocolitica and Escherichia coli, and was a 30 000-fold more potent antigen than IPP.
Abstract: Human Vg2Vd2 T cells are stimulated by prenyl pyrophosphates, such as isopentenyl pyrophosphate (IPP), and play important roles in mediating immunity against microbial pathogens and have potent anti-tumor activity. (E)-4-hydroxy-3-methyl-but-2-enyl pyrophosphate (HMBPP) has been identified as a metabolite in the 2-C-methyl-D-erythritol-4 phosphate (MEP) pathway for isoprenoid biosynthesis that is used by many bacteria and protozoan parasites. We find that HMBPP is the major Vg2Vd2 T-cell antigen for many bacteria, including Mycobacterium tuberculosis, Yersinia enterocolitica and Escherichia coli. HMBPP was a 30 000-fold more potent antigen than IPP. Using mutant bacteria, we show that bacterial antigen levels for Vg2Vd2 T cells are controlled by MEP pathway enzymes and find no evidence for the production of 3-formyl-1-butyl pyrophosphate. Moreover, HMBPP reactivity required only germ line-encoded Vg2Vd2 TCR elements and is present at birth. Importantly, we show that bacterial HMBPP levels correlated with their ability to expand Vg2Vd2 T cells in vivo upon engraftment into severe combined immunodeficiency–beige mice. Thus, the production of HMBPP by a microbial-specific isoprenoid pathway plays a major role in determining whether bacteria will stimulate Vg2Vd2 T cells in vivo. This preferential stimulation by a common microbial isoprenoid metabolite allows Vg2Vd2 T cells to respond to a broad array of pathogens using this pathway.
TL;DR: CD14(+) dermal APCs are therefore the dominant cutaneous APC population capable of sensing ligands recognized by CD206, CD209 and TLR2 and subsequently may have the potential to mature.
Abstract: We recently demonstrated that three antigen-presenting cell (APC) subsets exist in the healthy human dermis, CD14(+) and CD1a(+) dermal APCs and migratory dermal Langerhans cells. Here, we extend these findings by defining CD208 as an exclusive marker of migratory dermal Langerhans cells, confirming that migratory dermal Langerhans cells (CD1a(high) CD207(+) CD208(+)) and CD1a(+) dermal APCs (CD1a(mid) CD207(-) CD208(-)) are two distinct APC populations. Using flow cytometry and multicolor fluorescence immunohistochemistry, we demonstrated that there were striking differences between CD1a(+) and CD14(+) dermal APCs in their expression of pattern recognition receptors and maturation markers. Expression of Toll-like receptor (TLR) 2, CD206 and CD209 was largely restricted to CD14(+) dermal APCs. Consistent with these observations, most CD14(+) dermal APCs expressed an immature phenotype when compared with CD1a(+) dermal APCs, which expressed high levels of the maturation marker CD83 on their cell surface. However, a subset of CD14(+) dermal APCs also expressed cell-surface CD83, associated with a loss of cell-surface TLR2, suggesting that they have the capacity to mature. CD14(+) dermal APCs are therefore the dominant cutaneous APC population capable of sensing ligands recognized by CD206, CD209 and TLR2 and subsequently may have the potential to mature. CD68 expression was largely restricted to a subset of CD14(+) dermal APCs, while both CD14(+) and CD1a(+) dermal APCs expressed CD11b and CD11c. These findings have important implications for understanding cutaneous immune responses in humans and for the optimization of vaccine delivery via the skin.
TL;DR: Naive CD8(+) T cells are more sensitive to IL-7 that mediated the down-regulation of CD127, suggesting that these effects may have particular significance early in T-cell life cycle.
Abstract: IL-7 receptor alpha (CD127) signaling is essential for T-cell development and regulation of naive and memory T-cell homeostasis. Fewer CD8(+) T cells from HIV-infected patients express CD127 compared with healthy individuals, suggesting that specific host and/or viral factors regulate IL-7 receptor expression. Factors relevant to HIV infection that could potentially decrease CD127 expression on human CD8(+) T cells and the mechanisms by which this occurs were therefore evaluated. IL-7, but not HIV gp120, IL-1-beta, IL-6, IL-10, IL-13, transforming growth factor-beta or tumor necrosis factor-alpha, reduced CD127-surface expression and did so without altering CD127 mRNA expression. Furthermore, IL-7 did not increase the amount of cytoplasmic CD127 in CD8(+) T cells. Interestingly, IL-7 induced the shedding of CD127 from CD8(+) T cells, suggesting a mechanism that may contribute to the increased concentration of CD127 in the plasma of HIV(+) individuals, a novel finding reported here. Naive CD8(+) T cells are more sensitive to IL-7 that mediated the down-regulation of CD127, suggesting that these effects may have particular significance early in T-cell life cycle. Since CD127 down-regulation may be an important contributor to HIV-associated T-cell dysfunction, determining the mechanism thereof may prove to be of considerable significance.
TL;DR: The results suggest that IL-21 may play a cooperative role with IL-7 in modulating primary CD8(+) T-cell responses and may have important implications for immunotherapy of cancer.
Abstract: IL-21, a recently identified member of the common gamma-chain (gammac) receptor cytokine family, has been shown to be an important regulator of both innate and adaptive immune responses. In this study, we investigated whether IL-21 could synergize with another gammac cytokine, IL-7, to induce enhanced proliferation and effector function of tumor antigen-specific CD8(+) T cells. Our results showed that IL-21 could significantly augment the IL-7-induced expansion of cytotoxic T cells, possibly by preventing the cytokine-induced down-regulation of the IL-7Ralpha (CD127) on antigen-stimulated T cells. IL-21 also greatly enhanced the production of T(h)1 and inflammatory cytokines by activated T cells, including IFN-gamma, IL-2, tumor necrosis factor-alpha, granulocyte macrophage colony-stimulating factor, IL-1beta and IL-6. Finally, the addition of IL-21 to IL-7-cultured CTLs resulted in a considerably higher level of cytolytic activity, as measured by specific killing of tumor cells or antigen-pulsed target cells. These results suggest that IL-21 may play a cooperative role with IL-7 in modulating primary CD8(+) T-cell responses and may have important implications for immunotherapy of cancer.
TL;DR: It is suggested that Bcl6 in CD4(+) T cells plays a role in protection of memory precursor CD4 (+) T Cells from apoptosis and may involve in survivability of long-term memoryCD4(-) T cells.
Abstract: Bcl6 plays a role in the generation and maintenance of memory CD8 1 T cells. We analyzed here a role for Bcl6 in the generation of long-term memory CD4 1 T cells. Naive CD45RB 1 CD4 1 T cells from Bcl6-deficient DO11.10 (KJ1.26 1 ) transgenic mice were transferred into BALB/c mice and immunized with ovalbumin peptide and LPS. Long-term memory KJ1.26 1 CD4 1 T cells from wild-type mice were detected in the spleen, lungs and liver during 10 weeks after immunization; however, Bcl6-deficient KJ1.26 1 CD4 1 T cells were vanished completely in those organs 4 weeks after immunization. Since memory CD4 1 T cells can be generated from effector CD4 1 T cells, properties of Bcl6-deficient effector CD4 1 T cells were compared with those wild-type effector CD4 1 T cells 10 days after immunization. Numbers of IFN-g-non-producing CD45RB 2 , CD62L 1 or IL-7Ra 1 effector CD4 1 T cells in the spleen, lungs and liver were similar between Bcl6-deficient and wild-type CD4 1 T cells. However, the percentage of apoptotic cells in Bcl6-deficient effector CD4 1 T cells was higher than that in wild-type effector CD4 1 T cells. At the late effector phase, the number of IFN-g-non-producing cells and the percentage of apoptotic cells in Bcl6-deficient CD4 1 T cells were smaller and higher than those in wild-type CD4 1 T cells, respectively. These data suggest that Bcl6 in CD4 1 T cells plays a role in protection of memory precursor CD4 1 T cells from apoptosis and may involve in survivability of long-term memory CD4 1 T cells.
TL;DR: The over-expression of ULBP1 and 2 on mDCs facilitated NK cell proliferation and IFN-gamma production through a mDC-NK cell interaction in the presence of IL-2, reflecting the important role of NKG2DLs on human m DCs in m DC-mediated NK cell activation.
Abstract: Monocyte-derived dendritic cells (mDCs) and NK cells are reciprocally activate via cytokines and cell– cell contact. Although seven human NKG2D ligands (NKG2DLs), UL16-binding proteins (ULBP) 1, 2, 3 and 4, retinoic acid early transcript 1G (RAET1G) and MHC class I-related chains A and B, have been reported, the differential distribution and roles of these ligands in the maturation of human mDCs have not been elucidated. In the present study, we produced polyclonal antibodies (pAbs) directed against human ULBP1, 2 and 3. All these ULBPs were detected on human mDCs when probed by the pAbs, although their expression profiles were different. We next investigated what kinds of Toll-like receptor agonists and RNA viruses [influenza virus, human respiratory syncytial virus (RSV), measles virus and hepatitis C virus (HCV)] induced the expression of NKG2DLs on mDCs. ULBP1 was upregulated on mDCs in response to LPS or infection with RSV. The expression of ULBP2 was induced by LPS and poly I:C, indicating that the TIR-containing adapter molecule-1 (TIR domain-containing adaptor-inducing IFN) pathway is associated with ULBP2 induction. Although infection with HCV did not cause up-regulation of NKG2DLs, other RNA virus infections and poly I:C promoted expression of ULBP2 and RAET1G in an IFN-a/b-independent manner. Finally, the over-expression of ULBP1 and 2 on mDCs facilitated NK cell proliferation and IFN-g production through a mDC–NK cell interaction in the presence of IL-2. Hence, the results reflect the important role of NKG2DLs on human mDCs in mDC-mediated NK cell activation.
TL;DR: It is suggested that there is increased recognition of GI flora antigens by systemic antibodies in pIgR(-/-) mice, most probably as a result of increased access of antigen from the GI flora to the systemic immune compartment, and support the hypothesis that a major function of the secretory immune system is to return environmental antIGens to mucosal surfaces.
Abstract: The humoral response to the gastrointestinal (GI) flora was analyzed in secretory Ig (sIg)-deficient polymeric IgR (pIgR) � /� mice and otherwise congenic C57BL/6 mice. While both strains carried an ileal flora of similar size and composition, increased bacterial translocation to mesenteric lymph node was demonstrated in pIgR � /� mice. Serum IgA was greatly increased in pIgR � /� mice compared with C57BL/6 mice and reacted with commensal organisms and food. Serum IgG levels in pIgR � /� mice were increased to 6-fold above that of C57BL/6 mice and included specificities that bound to selected flora antigens. The enhanced recognition of flora antigens in pIgR � /� mice was explored using ovalbumin (OVA)-specific CD4 + T cells and feeding of low concentrations of OVA. Increased proliferation of transgenic T cells was observed in pIgR � /� mice, relative to C57BL/6 mice, suggesting elevated net uptake of protein antigens from the GI tract in the absence of sIg. These studies suggest that there is increased recognition of GI flora antigens by systemic antibodies in pIgR � /� mice, most probably as a result of increased access of antigens from the GI flora to the systemic immune compartment, and support the hypothesis that a major function of the secretory immune system is to return environmental antigens to mucosal surfaces.
TL;DR: The results indicate that upon microbial infection, macrophages produce IL-12 that renders NK cells highly responsive to TLR agonists to produce IFN-gamma and chemokines, which might in turn recruit and fully activate Macrophages, leading to the development of inflammatory foci presumably necessary for efficient microbial eradication.
Abstract: It is well established that IL-18R- and toll-like receptor (TLR)-mediated signalings share a common signal pathway mediated by signal adaptor, MyD88, and that IL-18 synergizes with IL-12 for IFN-gamma production by NK cells. Here, we investigated whether TLR agonists can replace IL-18 for production of IFN-gamma by NK cells. Freshly isolated NK cells possessed functional LPS receptor composed of TLR4/MD2 complex and of CD14, and also expressed other various tlrs. Hepatic CD3(-)DX5(+) NK cells produced IFN-gamma in response to TLR2 or TLR7 agonists only when co-stimulated with IL-12, indicating that TLR agonists synergize with IL-12 for IFN-gamma. The tlr2(-/-) or tlr7(-/-) NK cells could not produce IFN-gamma in response to IL-12 plus TLR2 or TLR7 ligands, respectively, indicating requirement of the corresponding TLRs. Furthermore, upon stimulation with these combinations, wild-type NK cells produced type 1 chemokines, such as CCL3, CCL4 and CCL5 as well. NK cells from bacterium (e.g. Propionibacterium acnes)-inoculated rag2(-/-) mice, when compared with those from naive mice, exhibited significantly enhanced capacity to produce these CC chemokines and IFN-gamma, suggesting that microbial infection enhances responsiveness of NK cells to TLR agonists. These results indicate that upon microbial infection, macrophages produce IL-12 that renders NK cells highly responsive to TLR agonists to produce IFN-gamma and chemokines, which might in turn recruit and fully activate macrophages, leading to the development of inflammatory foci presumably necessary for efficient microbial eradication. Thus, NK cells, like T cells, induce orchestrated immune responses in collaboration with macrophages to show potent host defense effects during early infectious phase.
TL;DR: It is proposed that APS sIVIG may be considered as potential specific therapeutic safe compound for developing a treatment for APS patient's early fetal loss.
Abstract: Objectives: Administration of intravenous Ig (IVIG) is a recognized, safe and efficient mode of immunomodulatory therapy for many autoimmune diseases Anti-idiotypic antibody binding to pathogenic autoantibodies and hence inhibition of binding to the corresponding antigen is one postulated mechanism of the beneficial effect of IVIG The aim of this study was to fractionate the antibeta-2-glycoprotein-I (b2GPI) anti-idiotypic antibodies from a commercial IVIG preparation and use it as a treatment in an experimental antiphospholipid syndrome (APS) mouse model Methods: Antib2GPI polyclonal antibodies were purified on a b2GPI column The purified antibodies were bound to CN‐Br-activated sepharose and employed for purification of IVIG-anti-anti-b2GPI (anti-idiotypic antibodies), defined as specific intravenous Ig (sIVIG) The idiotype specificities were confirmed by competition assays The effect of sIVIG in vitro was tested in a trophoblast and choriocarcinoma matrigel/invasion assay (ie proliferation and metalloproteinase> (MMP)2/MMP9 expression) and in vivo in a fetal loss model of APS Results: Anti-b2GPI antibodies inhibited human trophoblast cell invasion in vitro The function was attributed to the Fab portion of the anti-b2GPI Igs, since b2GPIrelated synthetic peptides specific for the Fab part of the anti-b2GPI antibodies neutralized its activity APS sIVIG fraction reduce human trophoblast invasion in vitro by 560 times more than the whole IVIG compound and improved the MMP2 and MMP9 production by trophoblast cells sIVIG improved significantly (200 times more) the pregnancy outcome in BALB/c mice passively infused with antib2GPI antibodies, in comparison to treatment with IVIG (P < 002) Conclusions: Based on the current results, we propose that APS sIVIG may be considered as potential specific therapeutic safe compound for developing a treatment for APS patient’s early fetal loss
TL;DR: It is clearly demonstrated that IL-6 is a critical factor for the induction of colitis by expansion of naive CD4(+) T cells in RAG2(-/-) mice, and the IL- 6-mediated signaling pathway may be a significant therapeutic target in T cell-mediated autoimmune diseases.
Abstract: Naive CD4 1 T cells rapidly proliferate to generate effector cells after encountering an antigen and small numbers survive as memory T cells in preparation for future immunological events. In the present work, adoptive transfer of naive CD4 1 T cells into RAG2 2/2 mice caused the generation of memory-type effector T cells including Th1, Th2, Th17 and regulatory T cells, and eventually induced T cell-dependent colitis. We found here that blocking of the IL-6R with a specific mAb remarkably inhibited the CD4 1 T cell-mediated colitis in parallel with the inhibition of Th17 cell generation. However, the transfer of naive CD4 1 T cells prepared from IL-17 2/2 mice still induced severe colitis. At the effector phase, the mAb significantly inhibited IL-17 but not IFN-g production. The blockade of IL-6 signaling enhanced the generation of IL-4- and IL-10-producing CD4 1 T cells, and inhibited upregulation of tumor necrosis factor -a mRNA expression in the colon. These findings clearly demonstrated that IL-6 is a critical factor for the induction of colitis by expansion of naive CD4 1 T cells in RAG2 2/2 mice. Thus, the IL-6-mediated signaling pathway may be a significant therapeutic
TL;DR: The results suggest that the perivascular spaces (PVS) of mice surrounding large blood vessels are a transit pathway for progenitor cells to immigrate into the thymus and for mature T cells to emigrate from theThymus.
Abstract: It is known that selected populations of lymphoid cells migrate into and from the adult thymus through blood vessels at the cortico-medullary junction and in the medulla. Here, we show that in the perivascular spaces (PVS) of mice surrounding large blood vessels, CD117-positive hematopoietic progenitor cells, CD4 single-positive (SP) and CD8SP T cells are located. However, developing thymocytes, CD25-positive cells and CD4 and CD8 double-positive cells, are not detectable in the PVS. After intravenous (i.v.) injection of CD117-positive bone marrow (BM) cells from C57BL/6 mice into non-irradiated RAG2 mutant mice i.v., donor-derived cells first preferentially migrate into the PVS within 30 min, and then the number of donor-derived cells in the thymic parenchyma increases. Likewise, newly developed mature T cells in the thymic parenchyma of RAG2 mutant mice transferred with wild-type BM cells migrate to the PVS, before leaving the thymus to the circulation. Accumulation of mature T cells was observed after treatment with sphingosine-1 phosphate receptor agonist FTY720 not only in the medulla but also in the thymic PVS. These results suggest that the PVS is a transit pathway for progenitor cells to immigrate into the thymus and for mature T cells to emigrate from the thymus.
TL;DR: It is demonstrated that exogenous BLyS treatment leads to an increase in B cell numbers, particularly anti-chromatin B cells; yet, their localization in the spleen and auto-antibody production remain unaffected and suggest a novel role for TACI in anti- chromatin B cell homeostasis and differentiation.
Abstract: B lymphocyte stimulator (BLyS), also known as B cell-activating factor, is a key positive regulator of B cell homeostasis, and elevated levels of BLyS have been observed in systemic lupus erythematosus (SLE) patients Given that anti-chromatin auto-antibodies are one of the hallmarks of SLE, we examined the role of BLyS and its receptors in the regulation of anti-chromatin B cells We demonstrate that exogenous BLyS treatment leads to an increase in B cell numbers, particularly anti-chromatin B cells; yet, their localization in the spleen and auto-antibody production remain unaffected We also examined transmembrane activator and CAML interactor (TACI), BLyS receptor 3 (BR3) and B cell maturation antigen expression on anti-chromatin B cells before and after receiving T cell help Interestingly, in the absence of T cell help, TACI expression is greater on immature anti-chromatin B cells compared with immature Tg(-) B cells, whereas BR3 levels are comparable After receiving T cell help, the anti-chromatin B cells that have differentiated into short-lived plasma cells no longer express BR3 but retain TACI These data suggest a novel role for TACI in anti-chromatin B cell homeostasis and differentiation
TL;DR: The functional analysis found that IL-21 significantly enhanced the cytokine-driven proliferation of CD4(+) helper T cells synergistically with IL-7 and IL-15 without T cell activation stimuli and may have a supportive role in the maintenance of CD 4(+) T cell subsets.
Abstract: IL-21 regulates certain functions of T cells, B cells, NK cells and dendritic cells. Although activated CD4(+) T cells produce IL-21, data identifying the specific CD4(+) T cell subsets that produce IL-21 are conflicting. In a previous study, mouse IL-21 message was detected in T(H)2, whereas human IL-21 (hIL-21) message was found in both T(H)1 and follicular helper T cells. To identify the IL-21-secreting cell populations in human, we established a hybridoma cell line producing an anti-hIL-21 mAb. Intracellular hIL-21-staining experiments showed that hIL-21 was mainly expressed in activated CD4(+) central memory T cells and in activated CD4(+) effector memory T cells, but not in activated CD4(+) naive T cells. Moreover, IL-21 was produced upon activation by some IFN-gamma-producing T(H)1-polarized cells and some IL-17-producing T(H)17-polarized cells, but not by IL-4-producing T(H)2-polarized cells. These results suggest that specific CD4(+) T cell populations produce IL-21. In the functional analysis, we found that IL-21 significantly enhanced the cytokine-driven proliferation of CD4(+) helper T cells synergistically with IL-7 and IL-15 without T cell activation stimuli. Taken together, IL-21 produced from CD4(+) memory T cells may have a supportive role in the maintenance of CD4(+) T cell subsets.
TL;DR: The tetramer-guided epitope mapping approach was used to identify CD4+ T-cell epitopes within the TT heavy chain restricted by 10 different class II alleles, and results contrast with the perceived notion that tetanus toxoid responses are dominated by universal CD4+.
Abstract: Tetanus toxoid is a routine positive control antigen for cellular assays. Previous studies identified multiple tetanus toxin (TT) epitopes, including some 'universal' epitopes. However, rigorous HLA-restricted study of tetanus toxoid responses is still lacking. In this study, the tetramer-guided epitope mapping approach was used to identify CD4+ T-cell epitopes within the TT heavy chain restricted by 10 different class II alleles. Of 106 peptides tested, 52 contained epitopes. Response frequencies toward specific epitopes varied, indicating prevalent and rare specificities. Most antigenic peptides (85%) were presented by one or two class II alleles. For peptides presented by three or more alleles, truncation studies revealed that some contained multiple epitopes. These results contrast with the perceived notion that tetanus toxoid responses are dominated by universal CD4+ T-cell epitopes. Rather these results illustrate heterogeneous T-cell responses for different class II alleles and individual-specific variation of the T-cell repertoire.
TL;DR: Significantly, it is shown that T cells that had become non-responsive to anti-CD3, either alone or together with CD80/CD86 co-stimulation, and thus were anergic, could be reactivated to proliferate when costimulated with 4-1BBL,Either alone or combined with CD 80/ CD86.
Abstract: Activation of T cells requires co-stimulation, in addition to signals through the antigen-receptor complex. Antigen encounter without adequate co-stimulation results in T-cell desensitization or anergy, a mechanism of peripheral tolerance and an apparent obstacle to cancer immunotherapy. One important co-stimulatory pathway involves CD28 engagement by CD80 or CD86. However, other ligand-receptor pairs can also provide co-stimulation and may have important functions modulating the immune response. Previous reports indicated that co-stimulation using 4-1BB ligand (4-1BBL) or agonistic anti-4-1BB antibodies could prolong T-cell responses, avoid activation-induced cell death and promote anti-tumour responses in mice. To further investigate the potential for cancer immunotherapy, we studied the effects of CD80/CD86 and 4-1BBL in repeated stimulation of human T cells and asked whether 4-1BBL might be capable of reversing anergy. We expressed CD80, CD86 and 4-1BBL in A549 lung carcinoma cells using adenovirus vectors and co-cultured these with human T cells stimulated with anti-CD3 antibody. Proliferation co-stimulated by CD80 or CD86 was transient; however, 4-1BBL-co-stimulated cultures continued to proliferate for up to 5 weeks, with repeated stimulation. Combined co-stimulation with CD80/CD86 and 4-1BBL also allowed continuous proliferation at a faster rate than either signal alone. Co-stimulation with 4-1BBL did not suppress expression of the inducible, inhibitory CD80/CD86R, CTLA-4. Significantly, we show that T cells that had become non-responsive to anti-CD3, either alone or together with CD80/CD86 co-stimulation, and thus were anergic, could be reactivated to proliferate when costimulated with 4-1BBL, either alone or combined with CD80/CD86.