bluuebunny/crossref_metadata_2025 huggingface dataset:
Uncoupling of Anergy from Developmental Arrest in Anti-Insulin B Cells Supports the Development of Autoimmune Diabetes
Authors: Acevedo-Suárez Carlos A. , Hulbert Chrys , Woodward Emily J. , Thomas James W.
Published: April 2014

Loss of tolerance is considered to be an early event that is essential for the development of autoimmune disease. In contrast to this expectation, autoimmune (type 1) diabetes develops in NOD mice that harbor an anti-insulin Ig transgene (125Tg), even though anti-insulin B cells are tolerant. Tolerance is maintained in a similar manner in both normal C57BL/6 and autoimmune NOD mice, as evidenced by B cell anergy to stimulation through their Ag receptor (anti-IgM), TLR4 (LPS), and CD40 (anti-CD40). Unlike B cells in other models of tolerance, anergic 125Tg B cells are not arrested in development, and they enter mature subsets of follicular and marginal zone B cells. In addition, 125Tg B cells remain competent to increase CD86 expression in response to both T cell-dependent (anti-CD40) and T cell-independent (anti-IgM or LPS) signals. Thus, for anti-insulin B cells, tolerance is characterized by defective B cell proliferation uncoupled from signals that promote maturation and costimulator function. In diabetes-prone NOD mice, anti-insulin B cells in this novel state of tolerance provide the essential B cell contribution required for autoimmune β cell destruction. These findings suggest that the degree of functional impairment, rather than an overt breach of tolerance, is a critical feature that governs B cell contribution to T cell-mediated autoimmune disease.
Transcriptional Profiling Reveals Complex Regulation of the Monocyte IL-1β System by IL-13
Authors: Scotton Chris J. , Martinez Fernando O. , Smelt Maaike J. , Sironi Marina , Locati Massimo , Mantovani Alberto , Sozzani Silvano
Published: April 2014

IL-4 and IL-13 are prototypic Th2 cytokines that generate an “alternatively activated” phenotype in macrophages. We used high-density oligonucleotide microarrays to investigate the transcriptional profile induced in human monocytes by IL-13. After 8-h stimulation with IL-13, 142 genes were regulated (85 increased and 57 decreased). The majority of these genes were related to the inflammatory response and innate immunity; a group of genes related to lipid metabolism was also identified, with clear implications for atherosclerosis. In addition to characteristic markers of alternatively activated macrophages, a number of novel IL-13-regulated genes were seen. These included various pattern recognition receptors, such as CD1b/c/e, TLR1, and C-type lectin superfamily member 6. Several components of the IL-1 system were regulated. IL-1RI, IL-1RII, and IL-1Ra were all up-regulated, whereas the IL-1β-converting enzyme, caspase 1, and IRAK-M were down-regulated. LPS-inducible caspase 1 enzyme activity was also reduced in IL-13-stimulated monocytes, with a consequent decrease in pro-IL-1β processing. These data reveal that IL-13 has a potent effect on the transcriptional profile in monocytes. The IL-13-induced modulation of genes related to IL-1 clearly highlights the tightly controlled and complex levels of regulation of the production and response to this potent proinflammatory cytokine.
Dynamics of Dendritic Cell Phenotype and Interactions with CD4+ T Cells in Airway Inflammation and Tolerance
Authors: Oriss Timothy B. , Ostroukhova Marina , Seguin-Devaux Carole , Dixon-McCarthy Barbara , Stolz Donna B. , Watkins Simon C. , Pillemer Brendan , Ray Prabir , Ray Anuradha
Published: April 2014

An emerging concept is that different types of dendritic cells (DCs) initiate different immune outcomes, such as tolerance vs inflammation. In this study, we have characterized the DCs from the lung draining lymph nodes of mice immunized for allergic airway inflammation or tolerance and examined their interactions with CD4+ T cells. The DC population derived from tolerized mice was predominantly CD11c+, B220+, Gr-1+, CD11b−, and MHC class IIlow, which resembled plasmacytoid-type DCs whereas DCs from the inflammatory condition were largely CD11c+, B220−, Gr-1−, CD11b+, and MHC class IIhigh resembling myeloid-type DCs. The DCs from the tolerogenic condition were poor inducers of T cell proliferation. DCs from both conditions induced T cell IL-4 production but the T cells cultured with tolerogenic DCs were unresponsive to IL-4 as indicated by inhibition of STAT6 activation and expression of growth factor-independent 1, which has been recently shown to be important for STAT6-activated Th2 cell expansion. Our data suggest that airway tolerance vs inflammation is determined by the DC phenotype in lung draining lymph nodes.
Fibroblast-Like Synoviocytes of Mesenchymal Origin Express Functional B Cell-Activating Factor of the TNF Family in Response to Proinflammatory Cytokines
Authors: Ohata Junko , Zvaifler Nathan J. , Nishio Mitsufumi , Boyle David L. , Kalled Susan L. , Carson Dennis A. , Kipps Thomas J.
Published: April 2014

Immunohistochemical analysis revealed that the intimal lining cells of synovial tissue of inflamed joints of patients with rheumatoid arthritis differed from that of normal joints or of diseased joints in osteoarthritis in that they stained with mAb specific for the B cell-activating factor of the TNF family (BAFF; also called BLyS). We generated fibroblast-like synoviocytes (FLS) cell lines that were bereft of myelomonocytic cells to examine whether mesenchymal-derived FLS could express this critical B cell survival factor. We found that FLS expressed low amounts of BAFF mRNA relative to that of myelomonocytic cells. However, when various cytokines/factors were added to such FLS cell lines, we found that IFN-γ or TNF-α were unique in that they could induce significant increases in BAFF mRNA and protein. Even minute amounts of IFN-γ primed FLS for TNF-α, allowing the latter to stimulate significantly higher levels of BAFF mRNA and protein than could TNF-α alone. Consistent with this, B cells cocultured with IFN-γ and/or TNF-α-treated FLS had a significantly greater viability than B cells cocultured with nontreated FLS. The enhanced protection of B cells afforded by IFN-γ/TNF-α-treated FLS was inhibited by the addition of BAFF-R:Fc fusion protein. We conclude that the proinflammatory cytokines IFN-γ and TNF-α can induce mesenchymal-derived FLS to express functional BAFF in vitro. The induced expression of BAFF on FLS by proinflammatory cytokines may enhance the capacity of such cells to protect B cells from apoptosis in inflammatory microenvironments in vivo.
The Expression of 11β-Hydroxysteroid Dehydrogenase Type I by Lymphocytes Provides a Novel Means for Intracrine Regulation of Glucocorticoid Activities
Authors: Zhang Tian Y. , Ding Xiaohong , Daynes Raymond A.
Published: April 2014

The 11β-hydroxysteroid dehydrogenase (11β-HSD) enzymes control the interconversion of active glucocorticoids (GCS) and their inactive 11-keto metabolites, a process commonly referred to as the cortisone/cortisol shuttle. Although the prereceptor metabolism of GCS by 11β-HSD is well documented in a variety of cells and tissues, it has not yet been carefully investigated in the major cell types of the immune system. In this study, we demonstrate that 11β-HSD1 transcripts, protein, and enzyme activities are actively expressed in murine CD4+, CD8+, and B220+ lymphocytes, as well as CD11c+ dendritic cells. Only reductase activity was observed in living cells, evidenced by the restricted conversion of cortisone to cortisol. Activation of CD4+ T cells increased their 11β-HSD1 activity, as did their polarization into Th1 or Th2 cells. CD4+ T cells isolated from aged donors (>16 mo) had increased 11β-HSD1 protein and an elevated capacity to convert cortisone to cortisol. The GCS generated in murine CD4+ T cells from their inactive 11-keto metabolites could activate the GCS receptor, demonstrated by an up-regulation of IL-7Rα and GCS-induced leucine zipper gene expression. The presence of a functional 11β-HSD1 provides lymphocytes with a novel intracrine regulatory mechanism that could influence such processes as lymphocyte development, effector function, and susceptibility to apoptosis. Thus, the presence of 11β-HSD1 provides an additional means to facilitate GCS influences over lymphocyte activities, uncoupled from the plasma concentration of GCS.
The Notch Regulator Numb Links the Notch and TCR Signaling Pathways
Authors: Anderson Ana C. , Kitchens Elizabeth A. , Chan Shiao Wei , St. Hill Charles , Jan Yuh Nung , Zhong Weimin , Robey Ellen A.
Published: April 2014

Both the Notch and TCR signaling pathways play an important role in T cell development, but the links between these signaling pathways are largely unexplored. The adapter protein Numb is a well-characterized inhibitor of Notch and also contains a phosphotyrosine binding domain, suggesting that Numb could provide a link between these pathways. We explored this possibility by investigating the physical interactions among Notch, Numb, and the TCR signaling apparatus and by examining the consequences of a Numb mutation on T cell development. We found that Notch and Numb cocluster with the TCR at the APC contact during Ag-driven T cell-APC interactions in both immature and mature T cells. Furthermore, Numb coimmunoprecipitates with components of the TCR signaling apparatus. Despite this association, T cell development and T cell activation occur normally in the absence of Numb, perhaps due to the expression of the related protein, Numblike. Together our data suggest that Notch and TCR signals may be integrated at the cell membrane, and that Numb may be an important adapter in this process.
Viral Delivery of an Epitope fromHaemophilus influenzaeInduces Central Nervous System Autoimmune Disease by Molecular Mimicry
Authors: Croxford J. Ludovic , Anger Holly A. , Miller Stephen D.
Published: April 2014

Multiple sclerosis (MS) is an autoimmune CNS demyelinating disease in which infection may be an important initiating factor. Pathogen-induced cross-activation of autoimmune T cells may occur by molecular mimicry. Infection with wild-type Theiler’s murine encephalomyelitis virus induces a late-onset, progressive T cell-mediated demyelinating disease, similar to MS. To determine the potential of virus-induced autoimmunity by molecular mimicry, a nonpathogenic neurotropic Theiler’s murine encephalomyelitis virus variant was engineered to encode a mimic peptide from protease IV of Haemophilus influenzae (HI), sharing 6 of 13 aa with the dominant encephalitogenic proteolipid protein (PLP) epitope PLP139–151. Infection of SJL mice with the HI mimic-expressing virus induced a rapid-onset, nonprogressive paralytic disease characterized by potent activation of self-reactive PLP139–151-specific CD4+ Th1 responses. In contrast, mice immunized with the HI mimic-peptide in CFA did not develop disease, associated with the failure to induce activation of PLP139–151-specific CD4+ Th1 cells. However, preinfection with the mimic-expressing virus before mimic-peptide immunization led to severe disease. Therefore, infection with a mimic-expressing virus directly initiates organ-specific T cell-mediated autoimmunity, suggesting that pathogen-delivered innate immune signals may play a crucial role in triggering differentiation of pathogenic self-reactive responses. These results have important implications for explaining the pathogenesis of MS and other autoimmune diseases.
RNase L and Double-Stranded RNA-Dependent Protein Kinase Exert Complementary Roles in Islet Cell Defense during Coxsackievirus Infection
Authors: Flodström-Tullberg Malin , Hultcrantz Monica , Stotland Alexandr , Maday Amy , Tsai Devin , Fine Cody , Williams Bryan , Silverman Robert , Sarvetnick Nora
Published: April 2014

Coxsackievirus (CV) is an important human pathogen that has been linked to the development of autoimmunity. An intact pancreatic β cell IFN response is critical for islet cell survival and protection from type 1 diabetes following CV infection. In this study, we show that IFNs trigger an antiviral state in β cells by inducing the expression of proteins involved in intracellular antiviral defense. Specifically, we demonstrate that 2′,5′-oligoadenylate synthetases (2-5AS), RNase L, and dsRNA-dependent protein kinase (PKR) are expressed by pancreatic islet cells and that IFNs (IFN-α and IFN-γ) increase the expression of 2-5AS and PKR, but not RNase L. Moreover, our in vitro studies uncovered that these pathways play important roles in providing unique and complementary antiviral activities that critically regulate the outcome of CV infection. The 2-5AS/RNase L pathway was critical for IFN-α-mediated islet cell resistance from CV serotype B4 (CVB4) infection and replication, whereas an intact PKR pathway was required for efficient IFN-γ-mediated repression of CVB4 infection and replication. Finally, we show that the 2-5AS/RNase L and the PKR pathways play important roles for host survival during a challenge with CVB4. In conclusion, this study has dissected the pathways used by distinct antiviral signals and linked their expression to defense against CVB4.
Activated NKT Cells Inhibit Autoimmune Diabetes through Tolerogenic Recruitment of Dendritic Cells to Pancreatic Lymph Nodes
Authors: Chen Yi-Guang , Choisy-Rossi Caroline-Morgane , Holl Thomas M. , Chapman Harold D. , Besra Gurdyal S. , Porcelli Steven A. , Shaffer Daniel J. , Roopenian Derry , Wilson S. Brian , Serreze David V.
Published: April 2014

NKT cell activation by α-galactosylceramide (α-GalCer) inhibits autoimmune diabetes in NOD mice, in part by inducing recruitment to pancreatic lymph nodes (PLNs) of mature dendritic cells (DCs) with disease-protective effects. However, how activated NKT cells promote DC maturation, and what downstream effect this has on diabetogenic T cells was unknown. Activated NKT cells were found to produce a soluble factor(s) inducing DC maturation. Initially, there was a preferential accumulation of mature DCs in the PLNs of α-GalCer-treated NOD mice, followed by a substantial increase in T cells. Adoptive transfer of a diabetogenic CD8 T cell population (AI4) induced a high rate of disease (75%) in PBS-treated NOD recipients, but not in those pretreated with α-GalCer (8%). Significantly, more AI4 T cells accumulated in PLNs of α-GalCer than PBS-treated recipients, while no differences were found in mesenteric lymph nodes from each group. Compared with those in mesenteric lymph nodes, AI4 T cells entering PLNs underwent greater levels of apoptosis, and the survivors became functionally anergic. NKT cell activation enhanced this process. Hence, activated NKT cells elicit diabetes protection in NOD mice by producing a soluble factor(s) that induces DC maturation and accumulation in PLNs, where they subsequently recruit and tolerize pathogenic T cells.
Cathepsin S Controls MHC Class II-Mediated Antigen Presentation by Epithelial Cells In Vivo
Authors: Beers Courtney , Burich Andrew , Kleijmeer Monique J. , Griffith Janice M. , Wong Phillip , Rudensky Alexander Y.
Published: April 2014

Epithelial cells at environmental interfaces provide protection from potentially harmful agents, including pathogens. In addition to serving as a physical barrier and producing soluble mediators of immunity, such as cytokines or antimicrobial peptides, these cells are thought to function as nonprofessional APCs. In this regard, intestinal epithelial cells are particularly prominent because they express MHC class II molecules at the site of massive antigenic exposure. However, unlike bone marrow-derived professional APC, such as dendritic cells or B cells, little is known about the mechanisms of MHC class II presentation by the nonprofessional APC in vivo. The former use the lysosomal cysteine protease cathepsin S (Cat S), whereas thymic cortical epithelial cells use cathepsin L (Cat L) for invariant chain degradation and MHC class II maturation. Unexpectedly, we found that murine Cat S plays a critical role in invariant chain degradation in intestinal epithelial cells. Furthermore, we report that nonprofessional APC present a class II-bound endogenous peptide to naive CD4 T cells in vivo in a Cat S-dependent fashion. These results suggest that in vivo, both professional and nonprofessional MHC class II-expressing APC use Cat S, but not Cat L, for MHC class II-mediated Ag presentation.
Roles for Common Cytokine Receptor γ-Chain-Dependent Cytokines in the Generation, Differentiation, and Maturation of NK Cell Precursors and Peripheral NK Cells in Vivo
Authors: Vosshenrich Christian A. J. , Ranson Thomas , Samson Sandrine I. , Corcuff Erwan , Colucci Francesco , Rosmaraki Eleftheria E. , Di Santo James P.
Published: April 2014

NK cells differentiate in adult mice from bone marrow hemopoietic progenitors. Cytokines, including those that signal via receptors using the common cytokine receptor γ-chain (γc), have been implicated at various stages of NK cell development. We have previously described committed NK cell precursors (NKPs), which have the capacity to generate NK cells, but not B, T, erythroid, or myeloid cells, after in vitro culture or transfer to a fetal thymic microenvironment. NKPs express the CD122 Ag (β chain of the receptors for IL-2/IL-15), but lack other mature NK markers, including NK1.1, CD49b (DX5), or members of the Ly49 gene family. In this report, we have analyzed the roles for γc-dependent cytokines in the generation of bone marrow NKP and in their subsequent differentiation to mature NK cells in vivo. Normal numbers of NKPs are found in γc-deficient mice, suggesting that NK cell commitment is not dependent on IL-2, IL-4, IL-7, IL-9, IL-15, or IL-21. Although IL-2, IL-4, and IL-7 have been reported to influence NK cell differentiation, we find that mice deficient in any or all of these cytokines have normal NK cell numbers, phenotype, and effector functions. In contrast, IL-15 plays a dominant role in early NK cell differentiation by maintaining normal numbers of immature and mature NK cells in the bone marrow and spleen. Surprisingly, the few residual NK cells generated in absence of IL-15 appear relatively mature, expressing a variety of Ly49 receptors and demonstrating lytic and cytokine production capacity.
Phosphatidylinositol 3-Kinase Regulates Thymic Exit
Authors: Barbee Susannah D. , Alberola-Ila Jose
Published: April 2014

To understand the role of PI3K during T cell development, we generated transgenic mice expressing the N terminus of the PI3K catalytic subunit (p110ABD; ABD, adaptor binding domain) in thymocytes. Expression of p110ABD activates endogenous p110 and results in the accumulation of mature single-positive CD3highheat-stable Aglow thymocytes. This is mostly due to a defect in emigration of those cells, as shown by the delayed appearance of peripheral T cells in neonatal transgenic mice and by competitive adoptive transfer experiments. Although the mechanisms underlying these effects of PI3K are not yet clear, our results show an important role for PI3K activity in the regulation of mature thymocyte exit to the periphery.
MAPK p38α Is Dispensable for Lymphocyte Development and Proliferation
Authors: Kim Jeong M. , White J. Michael , Shaw Andrey S. , Sleckman Barry P.
Published: April 2014

Signals mediated by the p38α MAPK have been implicated in many processes required for the development and effector functions of innate and adaptive immune responses. As mice deficient in p38α exhibit embryonic lethality, most analyses of p38α function in lymphocytes have relied on the use of pharmacologic inhibitors and dominant-negative or constitutively active transgenes. In this study, we have generated a panel of low passage p38α+/+, p38α+/−, and p38α−/− embryonic stem (ES) cells through the intercrossing of p38α+/− mice. These ES cells were used to generate chimeric mice by RAG-deficient blastocyst complementation, with the lymphocytes in these mice being derived entirely from the ES cells. Surprisingly, B and T cell development were indistinguishable when comparing chimeric mice generated with p38α+/+, p38α+/−, and p38α−/− ES cell lines. Moreover, proliferation of p38α−/− B and T cells in response to Ag receptor and non-Ag receptor stimuli was intact. Thus, p38α is not an essential component of signaling pathways required for robust B and T lymphocyte developmental, nor is p38α essential for the proliferation of mature B and T cells.
Igα/Igβ Complexes Generate Signals for B Cell Development Independent of Selective Plasma Membrane Compartmentalization
Authors: Fuentes-Pananá Ezequiel M. , Bannish Gregory , van der Voort Dustin , King Leslie B. , Monroe John G.
Published: April 2014

Ligand-induced BCR association with detergent-resistant plasma membrane compartments (lipid rafts) has been argued to be essential for initiating and/or sustaining Igα/Igβ-dependent BCR signaling. Because a fraction of the BCR and an even larger fraction of the preBCR associates with lipid rafts in the apparent absence of ligand stimulation, it has been proposed that raft-associated receptor complexes mediate the ligand-independent basal signaling events observed in resting B lineage cells. However, there is no direct evidence that localization of Igα/Igβ-containing complexes to detergent-resistant membrane compartments is absolutely required for the signaling events that drive B cell development. To address these issues we have designed surrogate preBCR/Igα/Igβ complexes that are incapable of ligand-induced aggregation and that are preferentially targeted to either raft or nonraft compartments. An analysis of their ability to promote the preBCR-dependent proB→preB cell transition of murine B cell progenitors revealed that expression of these surrogate receptor complexes at levels that approximate that of the conventional preBCR can drive B cell development in a manner independent of both aggregation and lipid raft localization.
The Low Affinity Fc Receptor for IgG Functions as an Effective Cytolytic Receptor for Self-Specific CD8 T Cells
Authors: Dhanji Salim , Tse Kathy , Teh Hung-Sia
Published: April 2014

We have recently described a population of self-Ag-specific murine CD8+ T cells with a memory phenotype that use receptors of both the adaptive and innate immune systems in the detection of transformed and infected cells. In this study we show that upon activation with IL-2 with or without Ag, between 10 and 20% of the activated self-specific CD8+ T cells express the low affinity FcR for IgG. By contrast, all IL-2-activated NK cells express high levels of this FcR. The FcR comprises the FcγRIIIα and FcRγ subunits. However, the FcRγ subunit also associates with the CD3 complex, and this association probably contributes to the low expression of FcR in activated cells. Although the FcR is expressed at a low level on activated self-specific CD8+ T cells, it functions very efficiently as a cytolytic receptor in ADCC. FcR-dependent killing occurred in the absence of TCR stimulation, but could be augmented by concurrent stimulation of the TCR. In addition to mediating ADCC, engagement of the FcR on self-specific CD8+ T cells results in the production of both IFN-γ and TNF-α. This is the first report of an activating FcR on self-specific murine CD8+αβ TCR+ T cells and establishes the importance of innate immune system receptors in the function of these self-specific CD8+ T cells.
Synthetic TLR Agonists Reveal Functional Differences between Human TLR7 and TLR8
Authors: Gorden Keith B. , Gorski Kevin S. , Gibson Sheila J. , Kedl Ross M. , Kieper William C. , Qiu Xiaohong , Tomai Mark A. , Alkan Sefik S. , Vasilakos John P.
Published: April 2014

Although TLR7 and TLR8 are phylogenetically and structurally related, their relative functions are largely unknown. The role of TLR7 has been established using TLR7-deficient mice and small molecule TLR7 agonists. The absence of TLR8-selective agonists has hampered our understanding of the role of TLR8. In this study TLR agonists selective for TLR7 or TLR8 were used to determine the repertoire of human innate immune cells that are activated through these TLRs. We found that TLR7 agonists directly activated purified plasmacytoid dendritic cells and, to a lesser extent, monocytes. Conversely, TLR8 agonists directly activated purified myeloid dendritic cells, monocytes, and monocyte-derived dendritic cells (GM-CSF/IL-4/TGF-β). Accordingly, TLR7-selective agonists were more effective than TLR8-selective agonists at inducing IFN-α- and IFN-regulated chemokines such as IFN-inducible protein and IFN-inducible T cell α chemoattractant from human PBMC. In contrast, TLR8 agonists were more effective than TLR7 agonists at inducing proinflammatory cytokines and chemokines, such as TNF-α, IL-12, and MIP-1α. Thus, this study demonstrated that TLR7 and TLR8 agonists differ in their target cell selectivity and cytokine induction profile.
Bone Marrow Is a Preferred Site for Homeostatic Proliferation of Memory CD8 T Cells
Authors: Becker Todd C. , Coley Shana M. , Wherry E. John , Ahmed Rafi
Published: April 2014

Proliferative renewal of memory CD8 T cells is essential for maintaining long-term immunity. In this study, we examined the contributions that various tissue microenvironments make toward the homeostatic proliferation of Ag-specific memory CD8 T cells. We found that dividing memory T cells were present in both lymphoid and nonlymphoid tissues. However, the bone marrow was the preferred site for proliferation and contained a major pool of the most actively dividing memory CD8 T cells. Adoptive transfer studies indicated that memory cells migrated through the bone marrow and divided there preferentially. These results show that the bone marrow is not only the source of stem cells for generating naive T cells but also provides the necessary signals for the self-renewal of memory T cells.
CD226 Expression Deficiency Causes High Sensitivity to Apoptosis in NK T Cells from Patients with Systemic Lupus Erythematosus
Authors: Tao Deng , Shangwu Liu , Qun Wu , Yan Liu , Wei Ju , Junyan Liu , Feili Gong , Boquan Jin , Jinquan Tan
Published: April 2014

Humans and mice with systemic lupus erythematosus (SLE) and related autoimmune diseases have reduced numbers of NK T cells. An association between NK T cell deficiency and autoimmune disease has been identified. However, the mechanisms for reduction of NK T cell number in patients with SLE are unknown. In the present study we report that NK T cells from active SLE patients are highly sensitive to anti-CD95-induced apoptosis compared with those from normal subjects and inactive SLE patients. CD226 expression is deficient on NK T cells from active SLE patients. The expression of one antiapoptotic member protein, survivin, is found to be selectively deficient in freshly isolated NK T cells from active SLE patients. CD226 preactivation significantly up-regulates survivin expression and activation, which can rescue active SLE NK T cells from anti-CD95-induced apoptosis. In transfected COS7 cells, we confirm that anti-CD95-mediated death signals are inhibited by activation of the CD226 pathway through stabilization of caspase-8 and caspase-3 and through activation of survivin. We therefore conclude that deficient expression of CD226 and survivin in NK T cells from active SLE is a molecular base of high sensitivity of the cells to anti-CD95-induced apoptosis. These observations offer a potential explanation for high apoptotic sensitivity of NK T cells from active SLE, and provide a new insight into the mechanism of reduction of NK T cell number in SLE and understanding the association between NK T cell deficiency and autoimmune diseases.
Heat Shock Protein 60: Specific Binding of Lipopolysaccharide
Authors: Habich Christiane , Kempe Karina , van der Zee Ruurd , Rümenapf Robert , Akiyama Hidehiko , Kolb Hubert , Burkart Volker
Published: April 2014

Human heat shock protein 60 (HSP60) has been shown to bind to the surface of innate immune cells and to elicit a proinflammatory response. In this study we demonstrate that the macrophage stimulatory property of recombinant human HSP60 is tightly linked to the HSP60 molecule and is lost after protease treatment. However, inhibition of macrophage stimulation was reached by the LPS-binding peptide magainin II amide. Indeed, HSP60 specifically bound [3H]LPS. [3H]LPS binding to HSP60 was saturable and competable by the unlabeled ligand. To identify the epitope region of the HSP60 molecule responsible for specific LPS binding, we analyzed the effect of several anti-HSP60 mAbs on HSP60-induced production of inflammatory mediators from macrophages. We identified only one mAb, clone 4B9/89, which blocked the macrophage stimulatory activity of the chaperone. The epitope specificity of this mAb points to the region aa 335–366 of HSP60. Clone 4B9/89 also strongly inhibited [3H]LPS binding to HSP60. A more detailed analysis was performed by screening with selected overlapping 20-mer peptides of the HSP60 sequence, covering the region aa 331–380. Only one peptide blocked LPS binding to HSP60, thereby restricting the potential LPS-binding region to aa 351–370 of HSP60. Finally, analysis of selected 15-mer peptides and a 13-mer peptide of the HSP60 sequence revealed that most of the LPS-binding region was accounted for by aa 354–365 of HSP60, with the motif LKGK being critical for binding. Our studies identified a defined region of HSP60 involved in LPS binding, thereby implicating a physiological role of human HSP60 as LPS-binding protein.
Limited Ability of Antigen-Specific Th1 Responses to Inhibit Th2 Cell Development In Vivo
Authors: Yasumi Takahiro , Katamura Kenji , Okafuji Ikuo , Yoshioka Takakazu , Meguro Taka-aki , Nishikomori Ryuta , Kusunoki Takashi , Heike Toshio , Nakahata Tatsutoshi
Published: April 2014

Th1 and Th2 cells mutually antagonize each other’s differentiation. Consequently, allergen-specific Th1 cells are believed to be able to suppress the development of Th2 cells and to prevent the development of atopic disorders. To determine whether a pre-existing Ag-specific Th1 response can affect the development of Th2 cells in vivo, we used an immunization model of Ag-pulsed murine dendritic cell (DC) transfer to induce distinct Th responses. When transferred into naive mice, Ag-pulsed CD8α+ DCs induced a Th1 response and the production of IgG2a, whereas CD8α− DCs primed a Th2 response and the production of IgE. In the presence of a pre-existing Ag-specific Th2 environment due to Ag-pulsed CD8α− DC transfer, CD8α+ DCs failed to prime Th1 cells. In contrast, CD8α− DCs could prime a Th2 response in the presence of a pre-existing Ag-specific Th1 environment. Moreover, exogenous IL-4 abolished the Th1-inducing potential of CD8α+ DCs in vitro, but the addition of IFN-γ did not effectively inhibit the potential of CD8α− DCs to prime IL-4-producing cells. Thus, Th1 and Th2 cells differ in their potential to inhibit the development of the other. This suggests that the early induction of allergen-specific Th1 cells before allergy sensitization will not prevent the development of atopic disorders.
Dynamic Interactions of Fcγ Receptor IIB with Filamin-Bound SHIP1 Amplify Filamentous Actin-Dependent Negative Regulation of Fcε Receptor I Signaling
Authors: Lesourne Renaud , Fridman Wolf H. , Daëron Marc
Published: April 2014

The engagement of high affinity receptors for IgE (FcεRI) generates both positive and negative signals whose integration determines the intensity of mast cell responses. FcεRI-positive signals are also negatively regulated by low affinity receptors for IgG (FcγRIIB). Although the constitutive negative regulation of FcεRI signaling was shown to depend on the submembranous F-actin skeleton, the role of this compartment in FcγRIIB-dependent inhibition is unknown. We show in this study that the F-actin skeleton is essential for FcγRIIB-dependent negative regulation. It contains SHIP1, the phosphatase responsible for inhibition, which is constitutively associated with the actin-binding protein, filamin-1. After coaggregation, FcγRIIB and FcεRI rapidly interact with the F-actin skeleton and engage SHIP1 and filamin-1. Later, filamin-1 and F-actin dissociate from FcR complexes, whereas SHIP1 remains associated with FcγRIIB. Based on these results, we propose a dynamic model in which the submembranous F-actin skeleton forms an inhibitory compartment where filamin-1 functions as a donor of SHIP1 for FcγRIIB, which concentrate this phosphatase in the vicinity of FcεRI and thereby extinguish activation signals.
Kinase-Independent Functions for Itk in TCR-Induced Regulation of Vav and the Actin Cytoskeleton
Authors: Dombroski Derek , Houghtling Richard A. , Labno Christine M. , Precht Patricia , Takesono Aya , Caplen Natasha J. , Billadeau Daniel D. , Wange Ronald L. , Burkhardt Janis K. , Schwartzberg Pamela L.
Published: April 2014

The Tec family kinase Itk is an important regulator of Ca2+ mobilization and is required for in vivo responses to Th2-inducing agents. Recent data also implicate Itk in TCR-induced regulation of the actin cytoskeleton. We have evaluated the requirements for Itk function in TCR-induced actin polarization. Reduction of Itk expression via small interfering RNA treatment of the Jurkat human T lymphoma cell line or human peripheral blood T cells disrupted TCR-induced actin polarization, a defect that correlated with decreased recruitment of the Vav guanine nucleotide exchange factor to the site of Ag contact. Vav localization and actin polarization could be rescued by re-expression of either wild-type or kinase-inactive murine Itk but not by Itk containing mutations affecting the pleckstrin homology or Src homology 2 domains. Additionally, we find that Itk is constitutively associated with Vav. Loss of Itk expression did not alter gross patterns of Vav tyrosine phosphorylation but appeared to disrupt the interactions of Vav with SLP-76. Expression of membrane-targeted Vav, Vav-CAAX, can rescue the small interfering RNA to Itk-induced phenotype, implicating the alteration in Vav localization as directly contributing to the actin polarization defect. These data suggest a kinase-independent scaffolding function for Itk in the regulation of Vav localization and TCR-induced actin polarization.
Ig-Independent Igβ Expression on the Surface of B Lymphocytes after B Cell Receptor Aggregation
Authors: Kremyanskaya Marina , Monroe John G.
Published: April 2014

In order for humoral immune responses to develop, B cells must be able to recognize, bind, and internalize Ags. These functions are performed by the BCR, which is also responsible for initiating and transducing activation signals necessary for B cell proliferation and differentiation. We have examined surface expression patterns of individual components of the BCR following anti-Ig- and Ag-induced aggregation. Specifically, the localization and expression levels of the Ag-binding component, surface Ig (sIg), and the Igβ component of the Igα/Igβ signaling unit were investigated to determine their individual participation in the internalization and signal transduction. Using primary murine B cells, we found that while >95% of the sIg is internalized following anti-Ig-induced aggregation, 20–30% of Igβ remains on the surface. These results suggest that sIg and Igβ may function independently following the initial stages of signal transduction.
A20 Is a Negative Regulator of IFN Regulatory Factor 3 Signaling
Authors: Saitoh Tatsuya , Yamamoto Masahiro , Miyagishi Makoto , Taira Kazunari , Nakanishi Makoto , Fujita Takashi , Akira Shizuo , Yamamoto Naoki , Yamaoka Shoji
Published: April 2014

IFN regulatory factor 3 (IRF-3) is a critical transcription factor that regulates an establishment of innate immune status following detection of viral pathogens. Recent studies have revealed that two IκB kinase (IKK)-like kinases, NF-κB-activating kinase/Traf family member-associated NF-κB activator-binding kinase 1 and IKK-i/IKKε, are responsible for activation of IRF-3, but the regulatory mechanism of the IRF-3 signaling pathway has not been fully understood. In this study, we report that IRF-3 activation is suppressed by A20, which was initially identified as an inhibitor of apoptosis and inducibly expressed by dsRNA. A20 physically interacts with NF-κB-activating kinase/Traf family member-associated NF-κB activator-binding kinase 1 and IKK-i/IKKε, and inhibits dimerization of IRF-3 following engagement of TLR3 by dsRNA or Newcastle disease virus infection, leading to suppression of the IFN stimulation response element- and IFN-β promoter-dependent transcription. Importantly, knocking down of A20 expression by RNA interference results in enhanced IRF-3-dependent transcription triggered by the stimulation of TLR3 or virus infection. Our study thus demonstrates that A20 is a candidate negative regulator of the signaling cascade to IRF-3 activation in the innate antiviral response.
A Common Polymorphism in the SFTPD Gene Influences Assembly, Function, and Concentration of Surfactant Protein D
Authors: Leth-Larsen Rikke , Garred Peter , Jensenius Henriette , Meschi Joseph , Hartshorn Kevan , Madsen Jens , Tornoe Ida , Madsen Hans O. , Sørensen Grith , Crouch Erika , Holmskov Uffe
Published: April 2014

Surfactant protein D (SP-D) plays important roles in the host defense against infectious microorganisms and in regulating the innate immune response to a variety of pathogen-associated molecular pattern. SP-D is mainly expressed by type II cells of the lung, but SP-D is generally found on epithelial surfaces and in serum. Genotyping for three single-nucleotide variations altering amino acids in the mature protein in codon 11 (Met11Thr), 160 (Ala160Thr), and 270 (Ser270Thr) of the SP-D gene was performed and related to the SP-D levels in serum. Individuals with the Thr/Thr11-encoding genotype had significantly lower SP-D serum levels than individuals with the Met/Met11 genotype. Gel filtration chromatography revealed two distinct m.w. peaks with SP-D immunoreactivity in serum from Met/Met11-encoding genotypes. In contrast, Thr/Thr11 genotypes lacked the highest m.w. form. A similar SP-D size distribution was found for recombinant Met11 and Thr11 expressed in human embryonic kidney cells. Atomic force microscopy of purified SP-D showed that components eluting in the position of the high m.w. peak consist of multimers, dodecamers, and monomers of subunits, whereas the second peak exclusively contains monomers. SP-D from both peaks bound to mannan-coated ELISA plates. SP-D from the high m.w. peak bound preferentially to intact influenza A virus and Gram-positive and Gram-negative bacteria, whereas the monomeric species preferentially bound to isolated LPS. Our data strongly suggest that polymorphic variation in the N-terminal domain of the SP-D molecule influences oligomerization, function, and the concentration of the molecule in serum.
Antigen-Specific T Cells Maintain an Effector Memory Phenotype during Persistent Trypanosoma cruzi Infection
Authors: Martin Diana L. , Tarleton Rick L.
Published: April 2014

Infection with the protozoan parasite Trypanosoma cruzi is a major cause of morbidity and mortality in Central and South America. Control of acute experimental infection with T. cruzi is dependent on a robust T cell and type 1 cytokine response. However, little evidence exists demonstrating the development and persistence of a potent antiparasite T cell memory response, and there has been much speculation that the majority of the immune response to T. cruzi infection is not directed against the parasite. In this study, we used an experimental mouse model of T. cruzi infection to test both the Ag specificity and the functional and phenotypic characteristics of the responding T cell population. We observed a vigorous antiparasite response from both CD4+ and CD8+ T cells that was maintained in the face of persistent infection. T cells from infected mice also proliferated in response to re-exposure to Ag, and CD8+ T cells underwent spontaneous proliferation when transferred to naive congenic mice, both characteristic of central memory T cells. Interestingly, T cells from infected mice showed significant down-regulation of CD62L, a characteristic associated with an effector memory phenotype. These results suggest that T cells maintained in mice with chronic T. cruzi infection are fully functional memory cells that cannot be easily categorized in the current central/effector memory paradigm.
A Chemotactic Peptide from Laminin α5 Functions as a Regulator of Inflammatory Immune Responses via TNFα-mediated Signaling
Authors: Adair-Kirk Tracy L. , Atkinson Jeffrey J. , Kelley Diane G. , Arch Robert H. , Miner Jeffrey H. , Senior Robert M.
Published: April 2014

Tissue injury triggers inflammatory responses that may result in release of degradation products or exposure of cryptic domains of extracellular matrix components. Previously, we have shown that a cryptic peptide (AQARSAASKVKVSMKF) in the α-chain of laminin-10 (α5β1γ1), a prominent basement membrane component, is chemotactic for both neutrophils (PMNs) and macrophages (Mφs) and induces matrix metalloproteinase-9 (MMP-9) production. To determine whether AQARSAASKVKVSMKF has additional effects on inflammatory cells, we performed microarray analysis of RNA from RAW264.7 Mφs stimulated with AQARSAASKVKVSMKF. Several cytokines and cytokine receptors were increased >3-fold in response to the laminin α5 peptide. Among these were TNF-α and one of its receptors, the p75 TNFR (TNFR-II), increasing 3.5- and 5.7-fold, respectively. However, the peptide had no effect on p55 TNFR (TNFR-I) expression. Corroborating the microarray data, the protein levels of TNF-α and TNFR-II were increased following stimulation of RAW264.7 cells with AQARSAASKVKVSMKF. In addition, we determined that the production of TNF-α and TNFR-II in response to AQARSAASKVKVSMKF preceded the production of MMP-9. Furthermore, using primary Mφs from mice deficient in TNFR-I, TNFR-II, or both TNF-α receptors (TNFRs), we determined that AQARSAASKVKVSMKF induces MMP-9 expression by Mφs through a pathway triggered by TNFR-II. However, TNF-α signaling is not required for AQARSAASKVKVSMKF-induced PMN release of MMP-9 or PMN emigration. These data suggest that interactions of inflammatory cells with basement membrane components may orchestrate immune responses by inducing expression of cytokines, recruitment of inflammatory cells, and release of proteinases.
Sle1ab Mediates the Aberrant Activation of STAT3 and Ras-ERK Signaling Pathways in B Lymphocytes
Authors: Liu Kui , Liang Chaoying , Liang Zhiyan , Tus Katalin , Wakeland Edward K.
Published: April 2014

The Sle1ab genomic interval on murine chromosome 1 mediates the loss of immune tolerance to chromatin resulting in antinuclear Abs (ANA) production in the lupus-prone NZM2410 mouse. Global gene expression analysis was used to identify the molecular pathways that are dysregulated at the initiation of B lymphocyte autoimmunity in B6.Sle1ab mice. This analysis identified that STAT3 and ras-ERK signaling pathways are aberrantly activated in Sle1ab B lymphocytes, consistent with increased production of IL-6 by splenic B lymphocytes and monocytes in B6.Sle1ab mice. In vitro treatment of splenic mononuclear cells isolated from ANA-positive Sle1ab mice with anti-IL-6 Ab or AG490, an inhibitor of STAT3 signaling pathway, suppressed ANA production in short-term culture, indicating that this pathway was essential to the production of autoantibodies. In vivo treatment of ANA-positive B6.Sle1ab mice with the ras pathway inhibitor, perillyl alcohol, suppressed the increase of ANA. These findings identify IL-6 as a early key cytokine in Sle1ab-mediated disease development and indicate that the STAT3 and ras-ERK signaling pathways are potential therapeutic targets for treating systemic lupus erythematosus.
Decoy Receptor 3 Increases Monocyte Adhesion to Endothelial Cells via NF-κB-Dependent Up-Regulation of Intercellular Adhesion Molecule-1, VCAM-1, and IL-8 Expression
Authors: Yang Chia-Ron , Hsieh Shie-Liang , Ho Feng-Ming , Lin Wan-Wan
Published: April 2014

Decoy receptor 3 (DcR3), a soluble receptor for FasL, LIGHT and TL1A, is highly expressed in cancer cells. We show that pretreatment of HUVECs with DcR3 enhances the adhesion of THP-1 and U937 cells and primary monocytes. A similar stimulatory effect of DcR3 on THP-1 adhesion was also observed in human microvascular endothelial cells (HMVECs). Flow cytometry and ELISA showed that DcR3-treated HUVECs exhibited significant increases in ICAM-1 and VCAM-1 expression. We also demonstrate the ability of DcR3 to stimulate the secretion of IL-8 by HUVECs. RT-PCR and reporter assays revealed that the expression of adhesion molecules and IL-8 are regulated at the level of gene transcription. Experiments with pyrrolidine dithiocarbamate indicated the involvement of an NF-κB signaling pathway. DcR3 was found to induce IκB kinase activation, IκB degradation, p65 nuclear translocation, and NF-κB DNA-binding activity. The enhancement by DcR3 of cell adhesion to HUVECs was not mimicked by the TL1A-Ab, which has been shown in our previous work to be a neutralizing Ab against TL1A, thereby inducing HUVECs angiogenesis. Moreover, DcR3-induced cell adhesion could be detected in human aortic endothelial cells (ECs) in which TL1A expression is lacking. Together, our data demonstrate that DcR3 increases monocyte adhesion to ECs via NF-κB activation, leading to the transcriptional up-regulation of adhesion molecules and IL-8 in ECs. This novel action appears not to be due to TL1A neutralization, but occurs through an as yet undefined target(s). This study implicates DcR3 in the relationship between inflammation and cancer development.
Protein Kinase Cα-Mediated Chemotaxis of Neutrophils Requires NF-κB Activity but Is Independent of TNFα Signaling in Mouse Skin In Vivo
Authors: Cataisson Christophe , Pearson Andrea J. , Torgerson Sara , Nedospasov Sergei A. , Yuspa Stuart H.
Published: April 2014

Protein kinase C (PKC) isoforms are major regulators of cutaneous homeostasis and mediate inflammation in response to 12-O-tetradecanoylphorbol-13-acetate (TPA). We have previously reported that transgenic mice overexpressing PKCα in the skin exhibit severe intraepidermal neutrophilic inflammation and keratinocyte apoptosis when treated topically with TPA. Activation of PKCα increases the production of TNFα and the transcription of chemotactic factors (MIP-2, KC, S100A8/A9), vascular endothelial growth factor, and GM-CSF in K5-PKCα keratinocytes. In response to PKCα activation, NF-κB translocates to the nucleus and this is associated with IκB phosphorylation and degradation. Preventing IκB degradation reduces both the expression of inflammation-associated genes and chemoattractant release. To determine whether TNFα mediated NF-κB translocation and subsequent expression of proinflammatory factors, K5-PKCα mice were treated systemically with a dimeric soluble form of p75 TNFR (etanercept) or crossed with mice deficient for both TNFR isoforms, and keratinocytes were cultured in the presence of TNFα-neutralizing Abs. The in vivo treatment and TNFR deficiency did not prevent inflammation, and the in vitro treatment did not prevent NF-κB nuclear translocation after TPA. Together these results implicate PKCα as a regulator of a subset of cutaneous cytokines and chemokines responsible for intraepidermal inflammation independent of TNFα. PKCα inhibition may have therapeutic benefit in some human inflammatory skin disorders.