bluuebunny/crossref_metadata_2025_split huggingface dataset:
Amyloid Precursor-Like Protein 2 Increases the Endocytosis, Instability, and Turnover of the H2-Kd MHC Class I Molecule
Authors: Tuli Amit , Sharma Mahak , McIlhaney Mary M. , Talmadge James E. , Naslavsky Naava , Caplan Steve , Solheim Joyce C. 
Published: April 2014

Abstract
The defense against the invasion of viruses and tumors relies on the presentation of viral and tumor-derived peptides to CTL by cell surface MHC class I molecules. Previously, we showed that the ubiquitously expressed protein amyloid precursor-like protein 2 (APLP2) associates with the folded form of the MHC class I molecule Kd. In the current study, APLP2 was found to associate with folded Kd molecules following their endocytosis and to increase the amount of endocytosed Kd. In addition, increased expression of APLP2 was shown to decrease Kd surface expression and thermostability. Correspondingly, Kd thermostability and surface expression were increased by down-regulation of APLP2 expression. Overall, these data suggest that APLP2 modulates the stability and endocytosis of Kd molecules.
Selection of the Alternative Exon 1 from thecd5Gene Down-Regulates Membrane Level of the Protein in B Lymphocytes
Authors: Garaud Soizic , Le Dantec Christelle , Berthou Christian , Lydyard Peter M. , Youinou Pierre , Renaudineau Yves 
Published: April 2014

AbstractThe human cd5 gene has two alternative exons 1: exon 1A (E1A) which encodes the full-length (FL) CD5 protein and exon 1B (E1B) which encodes a truncated (TR) isoform. The FL variant of CD5 protein is translocated to the plasma membrane, while its TR variant is retained in the cytoplasm. Because there is an inverse relationship between the levels of FL-CD5 and TR-CD5 in B cells, we have addressed the issue of how the selection of exon 1 is determined. In leukemic B cells, DNA methyltransferase (DNMT)1-induced methylation of E1B prevents its transcription. Furthermore, the level of mRNA for DNMT1 correlates inversely with that of mRNA for CD5-E1B. However, suppression of E1B transcription is incomplete, and some molecules of TR-CD5 continue to be synthesized. Bortezomid-induced inhibition of the proteasome establishes that these TR-CD5 molecules are cleared through the ubiquitin-proteasome pathway. Transfection of CD5 mutants into COS-1 cells locates the ubiquitin-binding site at the second destruction box of the extracellular region of CD5. Activation of the B cells by anti-IgM, Staphylococcus aureus Cowan I (SAC), or PMA up-regulates DNMT1, and thereby CD5-E1A mRNA at the expense of CD5-E1B mRNA. Aberrant synthesis of TR-CD5 is thus offset by balanced degradation of excessive protein. Dysregulation of these mechanisms reduces the expression level of membrane CD5, and thereby diminishes the threshold of the response by cells expressing CD5.
Deletion of Flagellin’s Hypervariable Region Abrogates Antibody-Mediated Neutralization and Systemic Activation of TLR5-Dependent Immunity
Authors: Nempont Clément , Cayet Delphine , Rumbo Martin , Bompard Coralie , Villeret Vincent , Sirard Jean-Claude 
Published: April 2014

Abstract
TLRs trigger immunity by detecting microbe-associated molecular patterns (MAMPs). Flagellin is a unique MAMP because it harbors 1) an antigenic hypervariable region and 2) a conserved domain involved in TLR5-dependent systemic and mucosal proinflammatory and adjuvant activities. In this study, the contribution of the flagellin domains in TLR5 activation was investigated. We showed that TLR5 signaling can be neutralized in vivo by flagellin-specific Abs, which target the conserved domain. However, deletions of flagellin’s hypervariable region abrogated the protein’s intrinsic ability to trigger the production of neutralizing Abs. The fact that MAMP-specific Abs block TLR-mediated responses shows that this type of neutralization is a novel mechanism for down-regulating innate immunity. The stimulation of mucosal innate immunity and adjuvancy to foreign Ag was not altered by the hypervariable domain deletions. In contrast, this domain is essential to trigger systemic innate immunity, suggesting that there are distinct mechanisms for TLR5 activation in systemic and mucosal compartments. In summary, specific MAMP determinants control the production of neutralizing Abs and the compartmentalization of innate responses.
Protein Kinase D1: A New Component in TLR9 Signaling
Authors: Park Jeoung-Eun , Kim Young-In , Yi Ae-Kyung 
Published: April 2014

AbstractProtein kinase D1 (PKD1) is expressed ubiquitously and regulates diverse cellular processes such as oxidative stress, gene expression, cell survival, and vesicle trafficking. However, the presence and function of PKD1 in monocytic cells are currently unknown. In this study, we provide evidence that PKD1 is involved in TLR9 signaling in macrophages. Class B-type CpG DNA (CpG-B DNA) induced activation of PKD1 via a pathway that is dependent on endosomal pH, TLR9, MyD88, and IL-1R-associated kinase 1 in macrophages. Upon CpG-B DNA stimulation, PKD1 interacted with the TLR9/MyD88/IL-1R-associated kinase/TNFR-associated factor 6 complex. Knockdown of PKD1 revealed that PKD1 is required for activation of NF-κB and MAPKs, and subsequent expression of cytokines in response to CpG-B DNA. Our findings identify PKD1 as a key signaling modulator in TLR9-mediated macrophage activation.
CREB, ATF, and AP-1 Transcription Factors Regulate IFN-γ Secretion by Human T Cells in Response to Mycobacterial Antigen
Authors: Samten Buka , Townsend James C. , Weis Steven E. , Bhoumik Anindita , Klucar Peter , Shams Homayoun , Barnes Peter F. 
Published: April 2014

AbstractIFN-γ production by T cells is pivotal for defense against many pathogens, and the proximal promoter of IFN-γ, −73 to −48 bp upstream of the transcription start site, is essential for its expression. However, transcriptional regulation mechanisms through this promoter in primary human cells remain unclear. We studied the effects of cAMP response element binding protein/activating transcription factor (CREB/ATF) and AP-1 transcription factors on the proximal promoter of IFN-γ in human T cells stimulated with Mycobacterium tuberculosis. Using EMSA, supershift assays, and promoter pulldown assays, we demonstrated that CREB, ATF-2, and c-Jun, but not cyclic AMP response element modulator, ATF-1, or c-Fos, bind to the proximal promoter of IFN-γ upon stimulation, and coimmunoprecipitation indicated the possibility of interaction among these transcription factors. Chromatin immunoprecipitation confirmed the recruitment of these transcription factors to the IFN-γ proximal promoter in live Ag-activated T cells. Inhibition of ATF-2 activity in T cells with a dominant-negative ATF-2 peptide or with small interfering RNA markedly reduced the expression of IFN-γ and decreased the expression of CREB and c-Jun. These findings suggest that CREB, ATF-2, and c-Jun are recruited to the IFN-γ proximal promoter and that they up-regulate IFN-γ transcription in response to microbial Ag. Additionally, ATF-2 controls expression of CREB and c-Jun during T cell activation.
Tyk2-Signaling Plays an Important Role in Host Defense against Escherichia coli through IL-23-Induced IL-17 Production by γδ T Cells
Authors: Nakamura Risa , Shibata Kensuke , Yamada Hisakata , Shimoda Kazuya , Nakayama Keiichi , Yoshikai Yasunobu 
Published: April 2014

Abstract
Tyrosine kinase 2 (Tyk2), a member of the JAK-signal transducer family, is involved in intracellular signaling triggered by various cytokines, including IL-23. We have recently reported that resident γδ T cells in the peritoneal cavity of naive mice produced IL-17 in response to IL-23. In this study, we examined importance of Tyk2-mediated signaling in the IL-17 production by γδ T cells using Tyk2 deficient (−/−) mice. γδ T cells in the peritoneal cavity of Tyk2−/− mice displayed effecter/memory phenotypes and TCR V repertoire similar to those in Tyk2+/+ mice and produced comparable level of IL-17 to those in Tyk2+/+ mice in response to PMA and ionomycin, indicating normal differentiation to IL-17-producing effectors in the absence of Tyk2-signaling. However, γδ T cells in Tyk2−/− mice produced less amount of IL-17 in response to IL-23 in vitro than those in Tyk2+/+ mice. Similarly, γδ T cells in the peritoneal cavity of Tyk2−/− mice showed severely impaired IL-17 production after an i.p. infection with E. coli despite comparable level of IL-23 production to Tyk2+/+ mice. As a consequence, Tyk2−/− mice showed a reduced infiltration of neutrophils and severely impaired bacterial clearance after Escherichia coli infection. These results indicate that Tyk2-signaling is critical for IL-23-induced IL-17 production by γδ T cells, which is involved in the first line of host defense by controlling neutrophil-mediated immune responses.
IL-10 Helps Control Pathogen Load during High-Level Bacteremia
Authors: Londoño Diana , Marques Adriana , Hornung Ronald L. , Cadavid Diego 
Published: April 2014

AbstractDuring relapsing fever borreliosis, a high pathogen load in the blood occurs at times of peak bacteremia. Specific IgM Abs are responsible for spirochetal clearance so in absence of B cells there is persistent high-level bacteremia. Previously, we showed that B cell-deficient mice persistently infected with Borrelia turicatae produce high levels of IL-10 and that exogenous IL-10 reduces bacteremia. This suggested that IL-10 helps reduce bacteremia at times of high pathogen load by a B cell-independent mechanism, most likely involving innate immunity. To investigate this possibility, we compared B. turicatae infection in RAG2/IL-10−/− and RAG2−/− mice. The results showed that IL-10 deficiency resulted in significantly higher bacteremia, higher TNF levels, and early mortality. Examination of the spleen and peripheral blood showed markedly increased apoptosis of immune cells in infected RAG2/IL-10−/− mice. Neutralization of TNF reduced apoptosis of leukocytes and splenocytes, increased production of IFN-γ by NK cells, increased phagocytosis in the spleen, decreased spirochetemia, and rescued mice from early death. Our results indicate that at times of high pathogen load, as during peak bacteremia in relapsing fever borreliosis, IL-10 protects innate immune cells from apoptosis via inhibition of TNF resulting in improved pathogen control.
Drak2 Contributes to West Nile Virus Entry into the Brain and Lethal Encephalitis
Authors: Wang Shuhui , Welte Thomas , McGargill Maureen , Town Terrence , Thompson Jesse , Anderson John F. , Flavell Richard A. , Fikrig Erol , Hedrick Stephen M. , Wang Tian 
Published: April 2014

Abstract
Death-associated protein kinase-related apoptosis-inducing kinase-2 (Drak2), a member of the death-associated protein family of serine/threonine kinases, is specifically expressed in T and B cells. In the absence of Drak2, mice are resistant to experimental autoimmune encephalomyelitis due to a decrease in the number of cells infiltrating the CNS. In the present study, we investigated the role of Drak2 in West Nile virus (WNV)-induced encephalitis and found that Drak2−/− mice were also more resistant to lethal WNV infection than wild-type mice. Although Drak2−/− mice had an increase in the number of IFN-γ-producing T cells in the spleen after infection, viral levels in the peripheral tissues were not significantly different between these two groups of mice. In contrast, there was a reduced viral load in the brains of Drak2−/− mice, which was accompanied by a decrease in the number of Drak2−/− CD4+ and CD8+ T cells in the brain following WNV infection. Moreover, we detected viral Ags in T cells isolated from the spleen or brain of WNV-infected mice. These results suggest that following a systemic infection, WNV might cross the blood brain barrier and enter the CNS by being carried by infected infiltrating T cells.
Low Molecular Weight Hyaluronic Acid Increases the Self-Defense of Skin Epithelium by Induction of β-Defensin 2 via TLR2 and TLR4
Authors: Gariboldi Silvia , Palazzo Marco , Zanobbio Laura , Selleri Silvia , Sommariva Michele , Sfondrini Lucia , Cavicchini Stefano , Balsari Andrea , Rumio Cristiano 
Published: April 2014

Abstract
In sites of inflammation or tissue injury, hyaluronic acid (HA), ubiquitous in the extracellular matrix, is broken down into low m.w. HA (LMW-HA) fragments that have been reported to activate immunocompetent cells. We found that LMW-HA induces activation of keratinocytes, which respond by producing β-defensin 2. This production is mediated by TLR2 and TLR4 activation and involves a c-Fos-mediated, protein kinase C-dependent signaling pathway. LMW-HA-induced activation of keratinocytes seems not to be accompanied by an inflammatory response, because no production of IL-8, TNF-α, IL-1β, or IL-6 was observed. Ex vivo and in vivo treatments of murine skin with LMW-HA showed a release of mouse β-defensin 2 in all layers of the epidermal compartment. Therefore, the breakdown of extracellular matrix components, for example after injury, stimulates keratinocytes to release β-defensin 2, which protects cutaneous tissue at a time when it is particularly vulnerable to infection. In addition, our observation might be important to open new perspectives in the development of possible topical products containing LMW-HA to improve the release of β-defensins by keratinocytes, thus ameliorating the self-defense of the skin for the protection of cutaneous tissue from infection by microorganisms.
Naive Precursor Frequencies and MHC Binding Rather Than the Degree of Epitope Diversity Shape CD8+ T Cell Immunodominance
Authors: Kotturi Maya F. , Scott Iain , Wolfe Tom , Peters Bjoern , Sidney John , Cheroutre Hilde , von Herrath Matthias G. , Buchmeier Michael J. , Grey Howard , Sette Alessandro 
Published: April 2014

Abstract
The primary CD8+ T cell response of C57BL/6J mice against the 28 known epitopes of lymphocytic choriomeningitis virus (LCMV) is associated with a clear immunodominance hierarchy whose mechanism has yet to be defined. To evaluate the role of epitope competition in immunodominance, we manipulated the number of CD8+ T cell epitopes that could be recognized during LCMV infection. Decreasing epitope numbers, using a viral variant lacking dominant epitopes or C57BL/6J mice lacking H-2Kb, resulted in minor response increases for the remaining epitopes and no new epitopes being recognized. Increasing epitope numbers by using F1 hybrid mice, delivery by recombinant vaccinia virus, or epitope delivery as a pool in IFA maintained the overall response pattern; however, changes in the hierarchy did become apparent. MHC binding affinity of these epitopes was measured and was found to not strictly predict the hierarchy since in several cases similarly high binding affinities were associated with differences in immunodominance. In these instances the naive CD8+ T cell precursor frequency, directly measured by tetramer staining, correlated with the response hierarchy seen after LCMV infection. Finally, we investigated an escape mutant of the dominant GP33–41 epitope that elicited a weak response following LCMV variant virus infection. Strikingly, dominance loss likely reflects a substantial reduction in frequencies of naive precursors specific for this epitope. Thus, our results indicate that an intrinsic property of the epitope (MHC binding affinity) and an intrinsic property of the host (naive precursor frequency) jointly dictate the immunodominance hierarchy of CD8+ T cell responses.
Adenovirus Vector-Induced Innate Inflammatory Mediators, MAPK Signaling, As Well As Adaptive Immune Responses Are Dependent upon Both TLR2 and TLR9 In Vivo
Authors: Appledorn Daniel M. , Patial Sonika , McBride Aaron , Godbehere Sarah , Van Rooijen Nico , Parameswaran Narayanan , Amalfitano Andrea 
Published: April 2014

Abstract
Adenovirus (Ad) vectors are promising candidates for both gene transfer and vaccine applications. In this study, we investigated the role of TLR2 in innate and adaptive immune responses to Ad and/or the transgene it expresses following systemic injection. We found that Ad directly activates ERK1/2 in vivo, but that initiation of ERK1/2 activation is primarily a MyD88/TLR2-independent, but Kupffer cell-dependent, event. The complexity of Ad-induced innate immune responses was confirmed when we also found that both TLR2 and MyD88 functions are required for the sustained activation of ERK1/2. Although we found that the initial activation of NF-κB by Ads is dependent upon MyD88, but independent of TLR2 in (non-Kupffer cells) the liver, TLR2 significantly influenced the Ad-induced late phase NF-κB activation. These very rapid responses were positively correlated with subsequent innate immune responses to the Ad vector, as our results confirmed that the induction of several cytokines and chemokines, and the expression of innate immune response genes following Ad injection were TLR2 dependent in vivo. The requirement of TLR2 in Ad-induced innate responses also correlated with significantly altered adaptive immune responses. For example, our results demonstrate that the generation of Ad-neutralizing Abs, and anti-transgene-specific Abs elicited subsequent to Ad vector treatments, are both dependent upon TLR2 functionality. Finally, we found that several Ad-induced innate immune responses are dependent on both TLR2 and TLR9. Therefore, this study confirms that several (but not all) Ad-induced innate and adaptive immune responses are TLR dependent.
Points of Control Exerted along the Macrophage-Endothelial Cell-Polymorphonuclear Neutrophil Axis by PECAM-1 in the Innate Immune Response of Acute Colonic Inflammation
Authors: Sugimoto Naohito , Rui Tao , Yang Min , Bharwani Sulaiman , Handa Osamu , Yoshida Norimasa , Yoshikawa Toshikazu , Kvietys Peter R. 
Published: April 2014

Abstract
PECAM-1 is expressed on endothelial cells and leukocytes. Its extracellular domain has been implicated in leukocyte diapedesis. In this study, we used PECAM-1−/− mice and relevant cells derived from them to assess the role of PECAM-1 in an experimental model of acute colonic inflammation with a predominant innate immune response, i.e., 2,4,6-trinitrobenzine sulfonic acid (TNBS). Using chimeric approaches, we addressed the points of control exerted by PECAM-1 along the macrophage-endothelial cell-polymorphonuclear neutrophil (PMN) axis. In vivo, TNBS-induced colitis was ameliorated in PECAM-1−/− mice, an event attributed to PECAM-1 on hematopoietic cells rather than to PECAM-1 on endothelial cells. The in vivo innate immune response was mimicked in vitro by using a construct of the vascular-interstitial interface, i.e., PMN transendothelial migration was induced by colonic lavage fluid (CLF) from TNBS mice or macrophages (MΦ) challenged with CLF. Using the construct, we confirmed that endothelial cell PECAM-1 does not play a role in PMN transendothelial migration. Although MΦ activation (NF-κB nuclear binding) and function (keratinocyte-derived chemokine production) induced by CLF was diminished in PECAM-1−/− MΦ, this did not affect their ability to promote PMN transendothelial migration. By contrast, PECAM-1−/− PMN did not adhere to or migrate across endothelial cell monolayers in response to CLF. Further, as compared with PECAM-1+/+ PMN, PECAM-1−/− PMN were less effective in orientating their CXCR2 receptors (polarization) in the direction of a chemotactic gradient. Collectively, our findings indicate that PECAM-1 modulation of PMN function (at a step before diapedesis) most likely contributes to the inflammation in a colitis model with a strong innate immune component.
In Vivo Interstitial Migration of Primitive Macrophages Mediated by JNK-Matrix Metalloproteinase 13 Signaling in Response to Acute Injury
Authors: Zhang Yong , Bai Xue-Tao , Zhu Kang-Yong , Jin Yi , Deng Min , Le Huang-Ying , Fu Yan-Fang , Chen Yi , Zhu Jiang , Look A. Thomas , Kanki John , Chen Zhu , Chen Sai-Juan , Liu Ting Xi 
Published: April 2014

Abstract
Interstitial cell migration through extracellular matrix is a hallmark of the inflammation response, tumor invasion, and metastasis. We have established a stable zebrafish transgenic line expressing enhanced GFP under the lysozyme C promoter for visualizing and measuring primitive macrophage migration in vivo. We show that tissue-resident primitive macrophages migrate rapidly through extracellular matrix to the site of acute injury induced by tail transection. Mechanistically, the specific inhibition of JNK, but not p38 and ERK, dramatically abolished the chemotactic migration in a dose-dependent manner, suppressing the trauma-induced recruitment of phosphorylated C-Jun transcription factor to proximal AP-1 sites in the promoter of matrix metalloproteinase 13 (mmp13), a gene specifically expressed in primitive macrophages during embryogenesis and required for the interstitial migration. Furthermore, dexamethasone suppressed the trauma-induced JNK phosphorylation and macrophage migration accompanied by simultaneous up-regulation of mkp-1, a well-known phosphatase capable of inactivating phosphorylated JNK. The results indicate that the JNK-Mmp13 signaling pathway plays an essential role in regulating the innate immune cell migration in response to severe injury in vivo.
Activated Protein C Up-Regulates IL-10 and Inhibits Tissue Factor in Blood Monocytes
Authors: Toltl Lisa J. , Beaudin Suzanne , Liaw Patricia C. ,   and the Canadian Critical Care Translational Biology Group
Published: April 2014

AbstractThe protective effect of recombinant activated protein C therapy in patients with severe sepsis likely reflects the ability of recombinant activated protein C to modulate multiple pathways implicated in sepsis pathophysiology. In this study, we examined the effects of recombinant activated protein C on the anti-inflammatory cytokine IL-10 and on the procoagulant molecule tissue factor (TF) in LPS-challenged blood monocytes. Treatment of LPS-stimulated monocytes with recombinant activated protein C resulted in an up-regulation of IL-10 protein production and mRNA synthesis. The up-regulation of IL-10 required the serine protease activity of recombinant activated protein C and was dependent on protease-activated receptor-1, but was independent of the endothelial protein C receptor. At the intracellular level, p38 MAPK activation was required for recombinant activated protein C-mediated up-regulation of IL-10. We further observed that incubation of LPS-stimulated monocytes with recombinant activated protein C down-regulated TF Ag and activity levels. This anticoagulant effect of recombinant activated protein C was dependent on IL-10 since neutralization of endogenously produced IL-10 abrogated the effect. In patients with severe sepsis, plasma IL-10 levels were markedly higher in those treated with recombinant activated protein C than in those who did not receive recombinant activated protein C. This study reveals novel regulatory functions of recombinant activated protein C, specifically the up-regulation of IL-10 and the inhibition of TF activity in monocytes. Our data further suggest that these activities of recombinant activated protein C are directly linked: the recombinant activated protein C-mediated up-regulation of IL-10 reduces TF in circulating monocytes.