bluuebunny/crossref_metadata_2025_split huggingface dataset:
Meningococcal Porin PorB Binds to TLR2 and Requires TLR1 for Signaling
Authors: Massari Paola , Visintin Alberto , Gunawardana Jay , Halmen Kristen A. , King Carol A. , Golenbock Douglas T. , Wetzler Lee M. 
Published: April 2014

Abstract
TLR2 plays a key role in the initiation of the cellular innate immune responses by a wide range of bacterial products. TLRs signaling, including TLR2 and its coreceptors TLR1 and TLR6, is mediated by a number of specific ligands. Although many of the TLR-mediated cell signaling pathways have been elucidated in the past few years, the molecular mechanisms that lead to cell activation are still poorly understood. In this study, we investigate the interaction of PorB from Neisseria meningitidis with TLR2 and describe the direct binding of a bacterial protein to TLR2 for the first time. Using labeled PorB, we demonstrate its binding to TLR2 both in its soluble form in vitro, and when it is over-expressed on the surface of human embryonic kidney 293 cells. We also show that TLR2-mediated binding of PorB is directly related to cellular activation. In addition, using 293 cells expressing the chimeric TLR2/TLR1 and TLR2/TLR6 complexes, we report the selectivity of PorB binding to the TLR2/TLR1 heterodimer, which is required for initiating signaling in transfected 293 cells and in murine B cells. Together, these data provide new evidence that TLR2 recognizes PorB through direct binding, and that PorB-induced cell activation is mediated by a TLR2/TLR1 complex.
Endotoxin-Induced Down-Regulation of Elk-3 Facilitates Heme Oxygenase-1 Induction in Macrophages
Authors: Chung Su Wol , Chen Yen-Hsu , Yet Shaw-Fang , Layne Matthew D. , Perrella Mark A. 
Published: April 2014

Abstract
Heme oxygenase-1 (HO-1) is a cytoprotective enzyme that is acutely induced by inflammatory stimuli, and the products of HO-1-mediated heme degradation have anti-inflammatory properties. In many different pathophysiologic states, the up-regulation of HO-1 has been shown to be beneficial in combating the detrimental consequences of increased inflammation. Ets transcription factors are known to be important mediators of inflammatory responses, and the ternary complex factor subfamily of Ets proteins has both transcriptional activation and repression activity. The present study demonstrates that of several ternary complex factor subfamily members, only Elk-3 represses HO-1 promoter activity in macrophages. Endotoxin administration to macrophages led to a dose-dependent decrease in endogenous Elk-3 mRNA levels, and this reduction in Elk-3 preceded the LPS-mediated up-regulation of HO-1 message. Analogous results also occurred in lung tissue of mice exposed to endotoxin. Two putative Ets binding sites (EBS1 and EBS2) are present in the downstream region of the murine HO-1 promoter (bp −125 and −93, respectively), and we recently showed that the EBS2 site is essential for HO-1 induction by endotoxin. In contrast, the present study demonstrates that the repressive effect of Elk-3 on HO-1 promoter activity is dependent on the EBS1 site. Taken together, our data reveal that Elk-3 serves as an important repressor of HO-1 gene transcription and contributes to the tight control of HO-1 gene regulation in the setting of inflammatory stimuli.
OX40 Ligation of CD4+ T Cells Enhances Virus-Specific CD8+ T Cell Memory Responses Independently of IL-2 and CD4+ T Regulatory Cell Inhibition
Authors: Yu Qigui , Yue Feng Yun , Gu Xiao X. , Schwartz Herbert , Kovacs Colin M. , Ostrowski Mario A. 
Published: April 2014

Abstract
We have previously shown that CD4+ T cells are required to optimally expand viral-specific memory CD8+ CTL responses using a human dendritic cell-T cell-based coculture system. OX40 (CD134), a 50-kDa transmembrane protein of the TNFR family, is expressed primarily on activated CD4+ T cells. In murine models, the OX40/OX40L pathway has been shown to play a critical costimulatory role in dendritic cell/T cell interactions that may be important in promoting long-lived CD4+ T cells, which subsequently can help CD8+ T cell responses. The current study examined whether OX40 ligation on ex vivo CD4+ T cells can enhance their ability to “help” virus-specific CTL responses in HIV-1-infected and -uninfected individuals. OX40 ligation of CD4+ T cells by human OX40L-IgG1 enhanced the ex vivo expansion of HIV-1-specific and EBV-specific CTL from HIV-1-infected and -uninfected individuals, respectively. The mechanism whereby OX40 ligation enhanced help of CTL was independent of the induction of cytokines such as IL-2 or any inhibitory effect on CD4+ T regulatory cells, but was associated with a direct effect on proliferation of CD4+ T cells. Thus, OX40 ligation on CD4+ T cells represents a potentially novel immunotherapeutic strategy that should be investigated to treat and prevent persistent virus infections, such as HIV-1 infection.
Impaired Protection against Mycobacterium bovis Bacillus Calmette-Guérin Infection in IL-15-Deficient Mice
Authors: Saito Kimika , Yajima Toshiki , Kumabe Shino , Doi Takehiko , Yamada Hisakata , Sad Subash , Shen Hao , Yoshikai Yasunobu 
Published: April 2014

Abstract
To investigate the potential role of endogenous IL-15 in mycobacterial infection, we examined protective immunity in IL-15-deficient (IL-15−/−) mice after infection with Mycobacterium bovis bacillus Calmette-Guérin (BCG) or recombinant OVA-expressing BCG (rBCG-OVA). IL-15−/− mice exhibited an impaired protection in the lung on day 120 after BCG infection as assessed by bacterial growth. CD4+ Th1 response capable of producing IFN-γ was normally detected in spleen and lung of IL-15−/− mice on day 120 after infection. Although Ag-specific CD8 responses capable of producing IFN-γ and exhibiting cytotoxic activity were detected in the lung on day 21 after infection with rBCG-OVA, the responses were severely impaired on days 70 and 120 in IL-15−/− mice. The degree of proliferation of Ag-specific CD8+ T cells in IL-15−/− mice was similar to that in wild-type mice during the course of infection with rBCG-OVA, whereas sensitivity to apoptosis of Ag-specific CD8+ T cells significantly increased in IL-15−/− mice. These results suggest that IL-15 plays an important role in the development of long-lasting protective immunity to BCG infection via sustaining CD8 responses in the lung.
Gliadin Stimulation of Murine Macrophage Inflammatory Gene Expression and Intestinal Permeability Are MyD88-Dependent: Role of the Innate Immune Response in Celiac Disease
Authors: Thomas Karen E. , Sapone Anna , Fasano Alessio , Vogel Stefanie N. 
Published: April 2014

AbstractRecent studies have demonstrated the importance of TLR signaling in intestinal homeostasis. Celiac disease (CD) is an autoimmune enteropathy triggered in susceptible individuals by the ingestion of gliadin-containing grains. In this study, we sought to test the hypothesis that gliadin initiates this response by stimulating the innate immune response to increase intestinal permeability and by up-regulating macrophage proinflammatory gene expression and cytokine production. To this end, intestinal permeability and the release of zonulin (an endogenous mediator of gut permeability) in vitro, as well as proinflammatory gene expression and cytokine release by primary murine macrophage cultures, were measured. Gliadin and its peptide derivatives, 33-mer and p31-43, were found to be potent inducers of both a zonulin-dependent increase in intestinal permeability and macrophage proinflammatory gene expression and cytokine secretion. Gliadin-induced zonulin release, increased intestinal permeability, and cytokine production were dependent on myeloid differentiation factor 88 (MyD88), a key adapter molecule in the TLR/IL-1R signaling pathways, but were neither TLR2- nor TLR4-dependent. Our data support the following model for the innate immune response to gliadin in the initiation of CD. Gliadin interaction with the intestinal epithelium increases intestinal permeability through the MyD88-dependent release of zonulin that, in turn, enables paracellular translocation of gliadin and its subsequent interaction with macrophages within the intestinal submucosa. There, the interaction of gliadin with macrophages elicits a MyD88-dependent proinflammatory cytokine milieu that facilitates the interaction of T cells with APCs, leading ultimately to the Ag-specific adaptive immune response seen in patients with CD.
Proinflammatory Cytokine Production in Liver Regeneration Is Myd88-Dependent, but Independent of Cd14, Tlr2, and Tlr4
Authors: Campbell Jean S. , Riehle Kimberly J. , Brooling John T. , Bauer Renay L. , Mitchell Claudia , Fausto Nelson 
Published: April 2014

Abstract
TNF and IL-6 are considered to be important to the initiation or priming phase of liver regeneration. However, the signaling pathways that lead to the production of these cytokines after partial hepatectomy (PH) have not been identified. Enteric-derived LPS appears to be important to liver regeneration, possibly by stimulating proinflammatory cytokine production after surgery. To determine whether LPS signaling pathways are involved in the regulation of the proinflammatory cytokines TNF and IL-6 during the priming phase of liver regeneration, we performed PH on mice lacking the TLRs Tlr4 and Tlr2, the LPS coreceptor, Cd14, and Myd88, an adapter protein involved in most TLR and IL-1R pathways. In MyD88 knockout (KO) mice after PH, both liver Tnf mRNA and circulating IL-6 levels were severely depressed compared with heterozygous or wild-type mice. Activation of STAT-3 and three STAT-3 responsive genes, Socs3, Cd14, and serum amyloid A2 were also blocked. In contrast, Tlr4, Tlr2, and Cd14 KO mice showed no deficits in the production of IL-6. Surprisingly, none of these KO mice showed any delay in hepatocyte replication. These data indicate that the LPS receptor TLR4, as well as TLR2 and CD14, do not play roles in regulating cytokine production or DNA replication after PH. In contrast, MyD88-dependent pathways appear to be responsible for TNF, IL-6, and their downstream signaling pathways.
Priming of Glomerular Mesangial Cells by Activated Macrophages Causes Blunted Responses to Proinflammatory Stimuli
Authors: Hayakawa Kunihiro , Meng Yiman , Hiramatsu Nobuhiko , Kasai Ayumi , Yamauchi Kozue , Yao Jian , Kitamura Masanori 
Published: April 2014

Abstract
Macrophage-mesangial cell interaction plays a crucial role in the pathogenesis of glomerulonephritis. Activated macrophages trigger mesangial cells to express an array of inflammation-associated genes via activation of NF-κB and AP-1. However, this inflammatory response is often transient and subsides spontaneously. We found that mesangial cells activated by bystander macrophages showed blunted responses of NF-κB to subsequent macrophage exposure. It was associated with sustained levels of IκBβ, but not IκBα. The tolerance observed was reversible and reproduced by conditioned media from activated macrophages (macrophage-conditioned medium (MφCM)). In vivo priming of mesangial cells by activated glomerular macrophages also caused the tolerance of mesangial cells. The macrophage-derived tolerance inducers were heat-labile, and multiple molecules were involved. Among inflammatory cytokines produced by macrophages, TNF-α and IL-1β were able to induce mesangial cell tolerance dose-dependently. The mesangial cell tolerance was also observed in activation of the MAPK-AP-1 pathway; i.e., phosphorylation of ERK, JNK, and p38 MAPK by macrophages was blunted when the cells were pre-exposed to MφCM. Induction of c-fos and c-jun was also abrogated in mesangial cells pre-exposed to MφCM, and the suppression was attenuated by blockade of MAPK activation during the first exposure to MφCM. These data elucidated that mesangial cells, once exposed to macrophages, become insensitive to subsequent activation by macrophages and proinflammatory stimuli. This self defense of glomerular cells may play a role in the resolution of macrophage-mediated, acute glomerulonephritis.
Impaired GATA3-Dependent Chromatin Remodeling and Th2 Cell Differentiation Leading to Attenuated Allergic Airway Inflammation in Aging Mice
Authors: Hasegawa Akihiro , Miki Takako , Hosokawa Hiroyuki , Hossain Mohammad B. , Shimizu Chiori , Hashimoto Kahoko , Kimura Motoko Y. , Yamashita Masakatsu , Nakayama Toshinori 
Published: April 2014

Abstract
Age-related changes in lymphocytes are most prominent in the T cell compartment. There have been substantial numbers of reports on T cell function in aged mice and humans, such as on the production of Th1 and Th2 cytokines, but the results show considerable variation and contradictions. In the present study, we used 8- to 12-mo-old aging mice and a well-established in vitro Th1/Th2 cell differentiation culture system to identify molecular defects in Th1/Th2 cell differentiation that can be detected in the relatively early stages of aging. The capability to differentiate into Th2 cells is reduced in aging mouse CD4+ T cells. Decreased activation of the ERK MAPK cascade upon TCR stimulation, but normal intracellular-free calcium ion concentration mobilization and normal IL-4-induced STAT6 activation were observed in aging mouse CD4+ T cells. In addition, reduced expression of GATA3 was detected in developing Th2 cells. Chromatin remodeling of the Th2 cytokine gene locus was found to be impaired. Th2-dependent allergic airway inflammation was milder in aging mice compared with in young adult mice. These results suggest that the levels of Th2 cell differentiation and resulting Th2-dependent immune responses, including allergic airway inflammation, decline during aging through defects in the activation of the ERK MAPK cascade, expression of GATA3 protein and GATA3-dependent chromatin remodeling of the Th2 cytokine gene locus. In the present study, we provide the first evidence indicating that a chromatin-remodeling event in T cells is impaired by aging.
HIV-1 Envelope Triggers Polyclonal Ig Class Switch Recombination through a CD40-Independent Mechanism Involving BAFF and C-Type Lectin Receptors
Authors: He Bing , Qiao Xugang , Klasse Per J. , Chiu April , Chadburn Amy , Knowles Daniel M. , Moore John P. , Cerutti Andrea 
Published: April 2014

Abstract
Switching from IgM to IgG and IgA is essential for antiviral immunity and requires engagement of CD40 on B cells by CD40L on CD4+ T cells. HIV-1 is thought to impair CD40-dependent production of protective IgG and IgA by inducing progressive loss of CD4+ T cells. Paradoxically, this humoral immunodeficiency is associated with B cell hyperactivation and increased production of nonprotective IgG and IgA that are either nonspecific or specific for HIV-1 envelope glycoproteins, including gp120. Nonspecific and gp120-specific IgG and IgA are sensitive to antiretroviral therapy and remain sustained in infected individuals with very few CD4+ T cells. One interpretation is that some HIV-1 Ags elicit IgG and IgA class switch DNA recombination (CSR) in a CD40-independent fashion. We show that a subset of B cells binds gp120 through mannose C-type lectin receptors (MCLRs). In the presence of gp120, MCLR-expressing B cells up-regulate the CSR-inducing enzyme, activation-induced cytidine deaminase, and undergo CSR from IgM to IgG and IgA. CSR is further enhanced by IL-4 or IL-10, whereas Ab secretion requires a B cell-activating factor of the TNF family. This CD40L-related molecule is produced by monocytes upon CD4, CCR5, and CXCR4 engagement by gp120 and cooperates with IL-4 and IL-10 to up-regulate MCLRs on B cells. Thus, gp120 may elicit polyclonal IgG and IgA responses by linking the innate and adaptive immune systems through the B cell-activating factor of the TNF family. Chronic activation of B cells through this CD40-independent pathway could impair protective T cell-dependent Ab responses by inducing immune exhaustion.
Distinct, Cross-Reactive Epitope Specificities of CD8 T Cell Responses Are Induced by Natural Hepatitis B Surface Antigen Variants of Different Hepatitis B Virus Genotypes
Authors: Riedl Petra , Bertoletti Antonio , Lopes Ross , Lemonnier Francois , Reimann Jörg , Schirmbeck Reinhold 
Published: April 2014

Abstract
We investigated the specific and cross-reactive CD8 T cell immunity to three natural variants (of different geno/serotype) of the small hepatitis B surface Ag (or S protein). The Dd-binding variants of the S201–209 epitope showed different immunogenicity. The loss of the consensus C-terminal (P9) anchor abrogated its immunogenicity. In contrast, a conservative (serine vs asparagine) exchange at P7 primed cross-reactive CD8 T cells that preferentially recognized the priming variant. Cross-reactive CD8 T cell responses to a variant could be primed in mice tolerant to an alternative variant of the Dd-binding S201–209 peptide. Loss of the C-terminal (P10) anchor in S185–194 eliminated its immunogenicity in HLA-A*0201(A2)-transgenic mice but two conservative exchanges (leucine vs valine in P2, and leucine vs isoleucine in P6) in S208–216 generated cross-reactive CD8 T cell responses with strong preference for the priming variant. Similar cross-reactive recognition of variant envelope epitopes were also found in S208–216-specific CD8 T cells from hepatitis B virus (HBV)-infected patients. Distinct CD8 T cell populations cross-reactive to natural variants of class I-restricted HBV epitopes can be primed by vaccination (of mice) or natural infection (of humans), and they may play a role in the “spontaneous remission” or the specific immunotherapy of chronic HBV infection.
Long-Term Retention of Mature NK1.1+ NKT Cells in the Thymus
Authors: Berzins Stuart P. , McNab Finlay W. , Jones Claerwen M. , Smyth Mark J. , Godfrey Dale I. 
Published: April 2014

Abstract
The NKT cell pool in the thymus contains immature (NK1.1−) and mature (NK1.1+) subsets that represent distinct linear stages of a linear developmental pathway. An unexplained paradox is why immature NK1.1− NKT cells are mainly exported to the periphery instead of the more mature and more abundant NK1.1+ NKT cells. In this study we have determined that mature NK1.1+ NKT cells are retained by the thymus to form an extremely long-lived resident population capable of rapid and prolonged production of IFN-γ and IL-4. The retention of mature NKT cells provides an explanation for why the periphery is mainly seeded by immature NK1.1− cells despite mature NK1.1+ NKT cells being more abundant in the thymus. This is the first study to identify a mature T cell subset retained within the thymus and is additional evidence of the distinct developmental pathways of mainstream T cells and NKT cells.
Immature NK Cells Suppress Dendritic Cell Functions during the Development of Leukemia in a Mouse Model
Authors: Ebata Kazumi , Shimizu Yukihiro , Nakayama Yasuhiro , Minemura Masami , Murakami Jun , Kato Tsutomu , Yasumura Satoshi , Takahara Terumi , Sugiyama Toshiro , Saito Shigeru 
Published: April 2014

Abstract
To analyze the mechanisms by which cancer cells escape from hosts’ immune surveillance, we investigated the changes in immune status during the progression of leukemia induced by injecting mice with WEHI-3B cells. In the bone marrow (BM) of leukemic mice, only DX5+CD3− cells were continuously increased, despite the progression of leukemia. In addition, DX5+CD3− cells were rapidly increased in peripheral blood (PB) 20 days after inoculation. We also found that myeloid dendritic cells (DCs) expressing low levels of I-Ad and having low allo-T cell stimulatory activity were markedly increased in PB and spleen. The increase in DX5+ cells in BM was thought to be induced by soluble factors from leukemic cells. DX5+ cells from leukemic mice were CD3−, B220−, Gr-1−, CD14−, CD94−, Ly-49C/F−, asialo GM1+, CD25+, CD122+, Thy-1bright, and c-kitdim and showed low killing activity against YAC-1 cells, suggesting that those DX5+ cells were immature NK cells. NK cells from leukemic PB down-regulated the expression of I-Ad on DCs, an effect mediated by TGF-β. Moreover, these NK cells significantly suppressed the allo-T cell stimulatory activity of DCs, an effect requiring cell-to-cell contact between NK cells and DCs and thought to involve CD25. Importantly, NK cells from leukemic PB inhibited generation of autotumor-specific CTL induced by DCs in primary MLR or by DC immunization. In conclusion, we identified circulating immature NK cells with immunosuppressive activities. These cells may be important for understanding the involvement of the host immune system during the development of leukemia.
TLR3-Involved Modulation of Pregnancy Tolerance in Double-Stranded RNA-Stimulated NOD/SCID Mice
Authors: Lin Yi , Liang Zhenhong , Chen Yijing , Zeng Yaoying 
Published: April 2014

Abstract
This study aims to extend understanding of the relationship between TLR3-involved cell signaling and dsRNA-induced embryo resorption. Upon stimulation of dsRNA, the resorption rate of embryos was boosted dramatically in syngeneic mating BALB/c mice, but not significantly influenced in syngeneic mating NOD/SCID mice. Accordingly, there was an enhanced cell surface expression of TLR3 on placental CD45+ cells derived from BALB/c mice, concomitant with both increased percentages of CD45+CD80+ cells and CD8α+CD80+ cells in flow cytometric analysis. In addition, both increased IL-2 and decreased IL-10 expression could be observed in CD45+ cell group in the intracellular detection by flow cytometry. In contrast, no such trends were observed in NOD/SCID model, and its resorption rate of embryos was kept at a low level throughout pregnancy. Neutralizing Abs against TLR3 could abrogate the embryo rejection induced by dsRNA in BALB/c mice, and simultaneously could reduce the CD80+ percentage in the CD45+ cell group. These results indicate that the interaction between dsRNA and TLR3 may be involved in the mobilization of CD45+CD80+ and CD8α+CD80+ cells, followed by the up-regulation of IL-2 and down-regulation of IL-10 expression at the feto-maternal interface, and finally resulting in embryo rejection. The relatively low responsiveness of NOD/SCID mice may be one of the reasons why these mice appeared to be resistant to dsRNA-induced embryo resorption.
Relationships between Distinct Blood Monocyte Subsets and Migrating Intestinal Lymph Dendritic Cells In Vivo under Steady-State Conditions
Authors: Yrlid Ulf , Jenkins Christopher D. , MacPherson G. Gordon 
Published: April 2014

Abstract
The origins of dendritic cells (DCs) are poorly understood. In inflammation, DCs can arise from blood monocytes (MOs), but their steady-state origin may differ, as shown for Langerhans cells. Two main subsets of MOs, defined by expression of different chemokine receptors, CCR2 and CX3CR1, have been described in mice and humans. Recent studies have identified the inflammatory function of CCR2highCX3CR1low MOs but have not defined unambiguously the origin and fate of CCR2lowCX3CR1high cells. In this study, we show that rat MOs can also be divided into CCR2highCX3CR1low(CD43low) and CCR2lowCX3CR1high(CD43high) subsets with distinct migratory properties in vivo. Using whole body perfusion to obtain MOs, including the marginating pool, we show by adoptive transfer that CD43low MOs can differentiate into CD43high MOs in blood without cell division. By adoptive transfer of blood MOs followed by collection of pseudoafferent lymph, we show for the first time that a small proportion of intestinal lymph DCs are derived from CCR2lowCX3CR1high(CD43high) blood MOs in vivo under steady-state conditions. This study confirms one of the possible origins of CCR2lowCX3CR1high blood MOs and indicate that they may contribute to migratory intestinal DCs in vivo in the absence of inflammatory stimuli.