bluuebunny/crossref_metadata_2025_split huggingface dataset:
Identification of a Novel Lipid Raft-Targeting Motif in Src Homology 2-Containing Phosphatase 1
Authors: Sankarshanan Mohan , Ma Zhong , Iype Tessy , Lorenz Ulrike 
Published: April 2014

Abstract
The tyrosine phosphatase Src homology 2-containing phosphatase 1 (SHP-1) is a key negative regulator of TCR-mediated signaling. Previous studies have shown that in T cells a fraction of SHP-1 constitutively localizes to membrane microdomains, commonly referred to as lipid rafts. Although this localization of SHP-1 is required for its functional regulation of T cell activation events, how SHP-1 is targeted to the lipid rafts was unclear. In this study, we identify a novel, six-amino acid, lipid raft-targeting motif within the C terminus of SHP-1 based on several biochemical and functional observations. First, mutations of this motif in the context of full-length SHP-1 result in the loss of lipid raft localization of SHP-1. Second, this motif alone restores raft localization when fused to a mutant of SHP-1 (SHP-1 ΔC) that fails to localize to rafts. Third, a peptide encompassing the 6-mer motif directly binds to phospholipids whereas a mutation of this motif abolishes lipid binding. Fourth, whereas full-length SHP-1 potently inhibits TCR-induced tyrosine phosphorylation of specific proteins, expression of a SHP-1-carrying mutation within the 6-mer motif does not. Additionally, although SHP-1 ΔC was functionally inactive, the addition of the 6-mer motif restored its functionality in inhibiting TCR-induced tyrosine phosphorylation. Finally, this 6-mer mediated targeting of SHP-1 lipid rafts was essential for the function of this phosphatase in regulating IL-2 production downstream of TCR. Taken together, these data define a novel 6-mer motif within SHP-1 that is necessary and sufficient for lipid raft localization and for the function of SHP-1 as a negative regulator of TCR signaling.
Pseudomonas aeruginosa Delays Kupffer Cell Death via Stabilization of the X-Chromosome-Linked Inhibitor of Apoptosis Protein
Authors: Ashare Alix , Monick Martha M. , Nymon Amanda B. , Morrison John M. , Noble Matthew , Powers Linda S. , Yarovinsky Timur O. , Yahr Timothy L. , Hunninghake Gary W. 
Published: April 2014

Abstract
Kupffer cells are important for bacterial clearance and cytokine production during infection. We have previously shown that severe infection with Pseudomonas aeruginosa ultimately results in loss of Kupffer cells and hepatic bacterial clearance. This was associated with prolonged hepatic inflammation. However, there is a period of time during which there is both preserved hepatic bacterial clearance and increased circulating TNF-α. We hypothesized that early during infection, Kupffer cells are protected against TNF-α-induced cell death via activation of survival pathways. KC13-2 cells (a clonal Kupffer cell line) were treated with P. aeruginosa (strain PA103), TNF-α, or both. At early time points, TNF-α induced caspase-mediated cell death, but PA103 did not. When we combined the two exposures, PA103 protected KC13-2 cells from TNF-α-induced cell death. PA103, in the setting of TNF exposure, stabilized the X-chromosome-linked inhibitor of apoptosis protein (XIAP). Stabilization of XIAP can occur via PI3K and Akt. We found that PA103 activated Akt and that pretreatment with the PI3K inhibitor, LY294002, prevented PA103-induced protection against TNF-α-induced cell death. The effects of LY294002 included decreased levels of XIAP and increased amounts of cleaved caspase-3. Overexpression of Akt mimicked the effects of PA103 by protecting cells from TNF-α-induced cell death and XIAP cleavage. Transfection with a stable, nondegradable XIAP mutant also protected cells against TNF-α-induced cell death. These studies demonstrate that P. aeruginosa delays TNF-α-induced Kupffer cell death via stabilization of XIAP.
Molecular Characterization of the Interaction between Porins of Neisseria gonorrhoeae and C4b-Binding Protein
Authors: Jarva Hanna , Ngampasutadol Jutamas , Ram Sanjay , Rice Peter A. , Villoutreix Bruno O. , Blom Anna M. 
Published: April 2014

Abstract
Neisseria gonorrhoeae, the causative agent of gonorrhea, is a natural infection only in humans. The resistance of N. gonorrhoeae to normal human serum killing correlates with porin (Por)-mediated binding to the complement inhibitor, C4b-binding protein (C4BP). The entire binding site for both porin molecules resides within complement control protein domain 1 (CCP1) of C4BP. Only human and chimpanzee C4BPs bind to Por1B-bearing gonococci, whereas only human C4BP binds to Por1A strains. We have now used these species-specific differences in C4BP binding to gonococci to map the porin binding sites on CCP1 of C4BP. A comparison between human and chimpanzee or rhesus C4BP CCP1 revealed differences at 4 and 12 amino acid positions, respectively. These amino acids were targeted in the construction of 13 recombinant human mutant C4BPs. Overall, amino acids T43, T45, and K24 individually and A12, M14, R22, and L34 together were important for binding to Por1A strains. Altering D15 (found in man) to N15 (found in rhesus) introduced a glycosylation site that blocked binding to Por1A gonococci. C4BP binding to Por1B strains required K24 and was partially shielded by additional glycosylation in the D15N mutant. Only those recombinant mutant C4BPs that bound to bacteria rescued them from 100% killing by rhesus serum, thereby providing a functional correlate for the binding studies and highlighting C4BP function in gonococcal serum resistance.
Inhibited Aortic Aneurysm Formation in BLT1-Deficient Mice
Authors: Ahluwalia Neil , Lin Alexander Y. , Tager Andrew M. , Pruitt Ivy E. , Anderson Thomas J. T. , Kristo Fjoralba , Shen Dongxiao , Cruz Anna R. , Aikawa Masanori , Luster Andrew D. , Gerszten Robert E. 
Published: April 2014

Abstract
Leukotriene B4 is a proinflammatory lipid mediator generated by the enzymes 5-lipoxygenase and leukotriene A4 hydrolase. Leukotriene B4 signals primarily through its high-affinity G protein-coupled receptor, BLT1, which is highly expressed on specific leukocyte subsets. Recent genetic studies in humans as well as knockout studies in mice have implicated the leukotriene synthesis pathway in several vascular pathologies. In this study, we tested the hypothesis that BLT1 is necessary for abdominal aortic aneurysm (AAA) formation, a major complication of atherosclerotic vascular disease. Chow-fed Apoe−/− and Apoe−/−/Blt1−/− mice were treated with a 4-wk infusion of angiotensin II (1000 ng/min/kg) beginning at 20 wk of age, in a well-established murine AAA model. We found a reduced incidence of AAA formation as well as concordant reductions in the maximum suprarenal/infrarenal diameter and total suprarenal/infrarenal area in the angiotensin II-treated Apoe−/−/Blt1−/− mice as compared with the Apoe−/− controls. Diminished AAA formation in BLT1-deficient mice was associated with significant reductions in mononuclear cell chemoattractants and leukocyte accumulation in the vessel wall, as well as striking reductions in the production of matrix metalloproteinases-2 and -9. Thus, we have shown that BLT1 contributes to the frequency and size of abdominal aortic aneurysms in mice and that BLT1 deletion in turn inhibits proinflammatory circuits and enzymes that modulate vessel wall integrity. These findings extend the role of BLT1 to a critical complication of vascular disease and underscore its potential as a target for intervention in modulating multiple pathologies related to atherosclerosis.
Differences in Expression, Affinity, and Function of Soluble (s)IL-4Rα and sIL-13Rα2 Suggest Opposite Effects on Allergic Responses
Authors: Khodoun Marat , Lewis Christina , Yang Jun-Qi , Orekov Tatyana , Potter Crystal , Wynn Thomas , Mentink-Kane Margaret , Khurana Hershey Gurjit K. , Wills-Karp Marsha , Finkelman Fred D. 
Published: April 2014

Abstract
IL-4 and IL-13 are each bound by soluble receptors (sRs) that block their activity. Both of these sRs (sIL-4Rα and sIL-13Rα2) are present in low nanogram per milliliter concentrations in the serum from unstimulated mice, but differences in affinity and half-life suggest differences in function. Serum IL-4/sIL-4Rα complexes rapidly dissociate, releasing active IL-4, whereas sIL-13Rα2 and IL-13 form a stable complex that has a considerably longer half-life than uncomplexed IL-13, sIL-13Rα2, IL-4, or sIL-4Rα. Approximately 25% of sIL-13Rα2 in serum is complexed to IL-13; this percentage and the absolute quantity of sIL-13Rα2 in serum increase considerably during a Th2 response. sIL-13Rα2 gene expression is up-regulated by both IL-4 and IL-13; the effect of IL-4 is totally IL-4Rα-dependent while the effect of IL-13 is partially IL-4Rα-independent. Inhalation of an IL-13/sIL-13Rα2 complex does not affect the expression of IL-13-inducible genes but increases the expression of two genes, Vnn1 and Pira-1, whose products activate APCs and promote neutrophilic inflammation. These observations suggest that sIL-4Rα predominantly sustains, increases, and diffuses the effects of IL-4, whereas sIL-13Rα2 limits the direct effects of IL-13 to the site of IL-13 production and forms a stable complex with IL-13 that may modify the quality and intensity of an allergic inflammatory response.
Select Plant Tannins Induce IL-2Rα Up-Regulation and Augment Cell Division in γδ T Cells
Authors: Holderness Jeff , Jackiw Larissa , Kimmel Emily , Kerns Hannah , Radke Miranda , Hedges Jodi F. , Petrie Charles , McCurley Patrick , Glee Pati M. , Palecanda Aiyappa , Jutila Mark A. 
Published: April 2014

Abstractγδ T cells are innate immune cells that participate in host responses against many pathogens and cancers. Recently, phosphoantigen-based drugs, capable of expanding γδ T cells in vivo, entered clinical trials with the goal of enhancing innate immune system functions. Potential shortcomings of these drugs include the induction of nonresponsiveness upon repeated use and the expansion of only the Vδ2 subset of human γδ T cells. Vδ1 T cells, the major tissue subset, are unaffected by phosphoantigen agonists. Using FACS-based assays, we screened primary bovine cells for novel γδ T cell agonists with activities not encompassed by the current treatments in an effort to realize the full therapeutic potential of γδ T cells. We identified γδ T cell agonists derived from the condensed tannin fractions of Uncaria tomentosa (Cat’s Claw) and Malus domestica (apple). Based on superior potency, the apple extract was selected for detailed analyses on human cells. The apple extract was a potent agonist for both human Vδ1 and Vδ2 T cells and NK cells. Additionally, the extract greatly enhanced phosphoantigen-induced γδ T cell expansion. Our analyses suggest that a tannin-based drug may complement the phosphoantigen-based drugs, thereby enhancing the therapeutic potential of γδ T cells.
IL-1α and IL-1β Are Endogenous Mediators Linking Cell Injury to the Adaptive Alloimmune Response
Authors: Rao Deepak A. , Tracey Kevin J. , Pober Jordan S. 
Published: April 2014

Abstract
Preoperative or perioperative ischemic injury of allografts predisposes to graft arteriosclerosis, the major cause of late graft failure. We hypothesize that injured tissues release mediators that increase the production of pathogenic cytokines by alloreactive T cells. We find that freeze-thaw lysates of human endothelial cells (EC) increase both IFN-γ and IL-17 production by human CD4+ T cells activated by HLA-DR+ allogeneic EC. Immunoadsorption of high-mobility group box 1 protein (HMGB1) reduces this activity in the lysates by about one-third, and recombinant HMGB1 increases T cell cytokine production. HMGB1 acts by inducing IL-1β secretion from contaminating monocytes via TLR4 and CD14. Upon removal of contaminating monocytes, the remaining stimulatory activity of EC lysates is largely attributable to IL-1α. Recombinant IL-1 directly augments IFN-γ and IL-17 production by activated memory CD4+ T cells, which express IL-1R1. Furthermore, IL-1 increases the frequency of alloreactive memory CD4+ T cells that produce IL-17, but not those that produce IFN-γ, in secondary cultures. Our results suggest that IL-1, released by injured EC or by HMGB1-stimulated monocytes, is a key link between injury and enhanced alloimmunity, offering a new therapeutic target for preventing late graft failure.
Intrahepatic Lymphocyte Expression of Dipeptidyl Peptidase I-Processed Granzyme B and Perforin Induces Hepatocyte Expression of Serine Proteinase Inhibitor 6 (Serpinb9/SPI-6)
Authors: Stout-Delgado Heather W. , Getachew Yonas , Miller Bonnie C. , Thiele Dwain L. 
Published: April 2014

Abstract
Human proteinase inhibitor 9 (PI-9/serpinB9) and the murine ortholog, serine proteinase inhibitor 6 (SPI-6/serpinb9) are members of a family of intracellular serine proteinase inhibitors (serpins). PI-9 and SPI-6 expression in immune-privileged cells, APCs, and CTLs protects these cells against the actions of granzyme B, and when expressed in tumor cells or virally infected hepatocytes, confers resistance to killing by CTL and NK cells. The present studies were designed to assess the existence of any correlation between granzyme B activity in intrahepatic lymphocytes and induction of hepatic SPI-6 expression. To this end, SPI-6, PI-9, and serpinB9 homolog expression was examined in response to IFN-α treatment and during in vivo adenoviral infection of the liver. SPI-6 mRNA expression increased 10- to 100-fold in the liver after IFN-α stimulation and during the course of viral infection, whereas no significant up-regulation of SPI-8 and &lt;5-fold increases in other PI-9/serpinB9 homolog mRNAs was observed. Increased SPI-6 gene expression during viral infection correlated with influxes of NK cells and CTL. Moreover, IFN-α-induced up-regulation of hepatocyte SPI-6 mRNA expression was not observed in NK cell-depleted mice. Additional experiments using genetically altered mice either deficient in perforin or unable to process or express granzyme B indicated that SPI-6 is selectively up-regulated in hepatocytes in response to infiltration of the liver by NK cells that express perforin and enzymatically active granzyme B.
Molecular Mimics Can Induce Novel Self Peptide-Reactive CD4+ T Cell Clonotypes in Autoimmune Disease
Authors: Ercolini Anne M. , Miller Stephen D. 
Published: April 2014

Abstract
It has been postulated that infectious agents may precipitate autoimmune disease when T cell responses raised against the pathogen cross-react with self-peptides, a phenomenon known as molecular mimicry. However, there are very little data available characterizing the similarity between the repertoire of the cross-reactive self-specific T cell population compared with the pathogen-specific T cell repertoire. In this study, we use immunoscope analysis to identify the T cell populations induced upon priming SJL/J mice with a pathogen-derived mimic of the immunodominant encephalitogenic myelin peptide PLP139–151, which is contained within the protease IV protein of Haemophilus influenzae (HAE574–586). We describe an IFN-γ-producing Vβ19+ T cell population in HAE574–586-primed mice that appears to be the “public clonotype” as it expanded in response to peptide in all mice tested. Critically this Vβ19+ T cell population is not expanded in mice primed with the self-peptide PLP139–151, indicating that mimics can induce the expansion of new self-reactive populations not initially present in the periphery of a host. This is the first description of the use of immunoscope analysis to characterize the cross-reactive anti-self T cell response induced by a molecular mimic.
Strength of Stimulus and Clonal Competition Impact the Rate of Memory CD8 T Cell Differentiation
Authors: Sarkar Surojit , Teichgräber Volker , Kalia Vandana , Polley Antonio , Masopust David , Harrington Laurie E. , Ahmed Rafi , Wherry E. John 
Published: April 2014

Abstract
The developmental pathways of long-lived memory CD8 T cells and the lineage relationship between memory T cell subsets remain controversial. Although some studies indicate the two major memory T cell subsets, central memory T (TCM) and effector memory T (TEM), are related lineages, others suggest that these subsets arise and are maintained independently of one another. In this study, we have investigated this issue and examined the differentiation of memory CD8 T cell subsets by tracking the lineage relationships of both endogenous and TCR transgenic CD8 T cell responses after acute infection. Our data indicate that TCR transgenic as well as nontransgenic TEM differentiate into TCM in the absence of Ag. Moreover, the rate of memory CD8 T cell differentiation from TEM into the self-renewing and long-lived pool of TCM is influenced by signals received during priming, including Ag levels, clonal competition, and/or the duration of infection. Although some TEM appear to not progress to TCM, the vast majority of TCM are derived from TEM. Thus, long-lasting, Ag-independent CD8 T cell memory results from progressive differentiation of memory CD8 T cells, and the rate of memory T cell differentiation is governed by events occurring early during T cell priming.
Duration of Antigen Expression In Vivo following DNA Immunization Modifies the Magnitude, Contraction, and Secondary Responses of CD8+ T Lymphocytes
Authors: Hovav Avi-Hai , Panas Michael W. , Rahman Shaila , Sircar Piya , Gillard Geoffrey , Cayabyab Mark J. , Letvin Norman L. 
Published: April 2014

Abstract
The duration of Ag expression in vivo has been reported to have a minimal impact on both the magnitude and kinetics of contraction of a pathogen-induced CD8+ T cell response. In this study, we controlled the duration of Ag expression by excising the ear pinnae following intradermal ear pinnae DNA immunization. This resulted in decreased magnitude, accelerated contraction and differentiation, and surprisingly greater secondary CD8+ T cell responses. Furthermore, we found delayed and prolonged Ag presentation in the immunized mice; however, this presentation was considerably decreased when the depot Ag was eliminated. These findings suggest that the magnitude and the contraction phase of the CD8+ T cell response following intradermal DNA immunization is regulated by the duration rather than the initial exposure to Ag.
LIGHT Is Critical for IL-12 Production by Dendritic Cells, Optimal CD4+ Th1 Cell Response, and Resistance to Leishmania major
Authors: Xu Guilian , Liu Dong , Okwor Ifeoma , Wang Yang , Korner Heinrich , Kung Sam K. P. , Fu Yang-Xin , Uzonna Jude E. 
Published: April 2014

Abstract
Although studies indicate LIGHT (lymphotoxin (LT)-like, exhibits inducible expression and competes with HSV glycoprotein D for herpes virus entry mediator (HVEM), a receptor expressed by T lymphocytes) enhances inflammation and T cell-mediated immunity, the mechanisms involved in this process remain obscure. In this study, we assessed the role of LIGHT in IL-12 production and development of CD4+ Th cells type one (Th1) in vivo. Bone marrow-derived dendritic cells from LIGHT−/− mice were severely impaired in IL-12p40 production following IFN-γ and LPS stimulation in vitro. Furthermore, blockade of LIGHT in vitro and in vivo with HVEM-Ig and LT β receptor (LTβR)-Ig leads to impaired IL-12 production and defective polyclonal and Ag-specific IFN-γ production in vivo. In an infection model, injection of HVEM-Ig or LTβR-Ig into the usually resistant C57BL/6 mice results in defective IL-12 and IFN-γ production and severe susceptibility to Leishmania major that was reversed by rIL-12 treatment. This striking susceptibility to L. major in mice injected with HVEM-Ig or LTβR-Ig was also reproduced in LIGHT−/− → RAG1−/− chimeric mice. In contrast, L. major-infected LTβ−/− mice do not develop acute disease, suggesting that the effect of LTβR-Ig is not due to blockade of membrane LT (LTα1β2) signaling. Collectively, our data show that LIGHT plays a critical role for optimal IL-12 production by DC and the development of IFN-γ-producing CD4+ Th1 cells and its blockade results in severe susceptibility to Leishmania major.
Impaired Macrophage Function Underscores Susceptibility to Salmonella in Mice Lacking Irgm1 (LRG-47)
Authors: Henry Stanley C. , Daniell Xiaojou , Indaram Maanasa , Whitesides John F. , Sempowski Gregory D. , Howell David , Oliver Tim , Taylor Gregory A. 
Published: April 2014

Abstract
IRG proteins, or immunity-related GTPases (also known as p47 GTPases), are a group of IFN-regulated proteins that are highly expressed in response to infection. The proteins localize to intracellular membranes including vacuoles that contain pathogens in infected macrophages and other host cells. Current data indicate that the IRG protein Irgm1 (LRG-47) is critical for resistance to intracellular bacteria. This function is thought to be a consequence of regulating the survival of vacuolar bacteria in host cells. In the current work, the role of Irgm1 in controlling resistance to Salmonella typhimurium was explored to further define the mechanism through which the protein regulates host resistance. Irgm1-deficient mice displayed increased susceptibility to this bacterium that was reflected in increased bacterial loads in spleen and liver and decreased maturation of S. typhimurium granulomas. The mice also displayed an inability to concentrate macrophages at sites of bacterial deposition. In vitro, the ability of Irgm1-deficient macrophages to suppress intracellular growth of S. typhimurium was impaired. Furthermore, adhesion and motility of Irgm1-deficient macrophages after activation with IFN-γ was markedly decreased. Altered adhesion/motility of those cells was accompanied by changes in cell morphology, density of adhesion-associated proteins, and actin staining. Together, these data suggest that in addition to regulating the maturation of pathogen-containing vacuoles, Irgm1 plays a key role in regulating the adhesion and motility of activated macrophages.
HIV Impairs TNF-α Mediated Macrophage Apoptotic Response to Mycobacterium tuberculosis
Authors: Patel Naimish R. , Zhu Jinping , Tachado Souvenir D. , Zhang Jianmin , Wan Zhi , Saukkonen Jussi , Koziel Henry 
Published: April 2014

Abstract
The factors that contribute to the exceptionally high incidence of Mycobacterium tuberculosis (MTb) disease in HIV+ persons are poorly understood. Macrophage apoptosis represents a critical innate host cell response to control MTb infection and limit disease. In the current study, virulent live or irradiated MTb (iMTbRv) induced apoptosis of differentiated human U937 macrophages in vitro, in part dependent on TNF-α. In contrast, apoptosis of differentiated HIV+ human U1 macrophages (HIV+ U937 subclone) was markedly reduced in response to iMTbRv and associated with significantly reduced TNF-α release, whereas apoptosis and TNF-α release were intact to TLR-independent stimuli. Furthermore, reduced macrophage apoptosis and TNF-α release were independent of MTb phagocytosis. Whereas surface expression of macrophage TLR2 and TLR4 was preserved, IL-1 receptor associated kinase-1 phosphorylation and NF-κB nuclear translocation were reduced in HIV+ U1 macrophages in response to iMTbRv. These findings were confirmed using clinically relevant human alveolar macrophages (AM) from healthy persons and asymptomatic HIV+ persons at clinical risk for MTb infection. Furthermore, in vitro HIV infection of AM from healthy persons reduced both TNF-α release and AM apoptosis in response to iMTbRv. These data identify an intrinsic specific defect in a critical macrophage cellular response to MTb that may contribute to disease pathogenesis in HIV+ persons.