bluuebunny/crossref_metadata_2025_split huggingface dataset:
Point Mutations in or Near the Antigen-Binding Groove of HLA-DR3 Implicate Class II-Associated Invariant Chain Peptide Affinity as a Constraint on MHC Class II Polymorphism
Authors: Doebele Robert C. , Pashine Achal , Liu Wendy , Zaller Dennis M. , Belmares Michael , Busch Robert , Mellins Elizabeth D. 
Published: April 2014

AbstractDuring maturation of MHC II molecules, newly synthesized and assembled complexes of MHC II αβ dimers with invariant chain (Ii) are targeted to endosomes, where Ii is proteolyzed, leaving remnant class II-associated Ii peptides (CLIP) in the MHC II peptide binding groove. CLIP must be released, usually with assistance from the endosomal MHC II peptide exchange factor, HLA-DM, before MHC II molecules can bind endosomal peptides. Structural factors that control rates of CLIP release remain poorly understood, although peptide side chain-MHC II specificity pocket interactions and MHC II polymorphism are important. Here we report that mutations βS11F, βS13Y, βQ70R, βK71E, βK71N, and βR74Q, which map to the P4 and P6 pockets of the groove of HLA-DR3 molecules, as well as αG20E adjacent to the groove, are associated with elevated CLIP in cells. Most of these mutations increase the resistance of CLIP-DR3 complexes to dissociation by SDS. In vitro, the groove mutations increase the stability of CLIP-DR3 complexes to dissociation. Dissociation rates in the presence of DM, as well as coimmunoprecipitation of some mutant DR3 molecules with DM, are also diminished. The profound phenotypes associated with some of these point mutations suggest that the need to maintain efficient CLIP release represents a constraint on naturally occurring MHC II polymorphism.
Absence of CC Chemokine Ligand 2 Results in an Altered Th1/Th2 Cytokine Balance and Failure to ExpelTrichuris murisInfection
Authors: deSchoolmeester Matthew L. , Little Matthew C. , Rollins Barrett J. , Else Kathryn J. 
Published: April 2014

AbstractDespite a growing understanding of the role of cytokines in immunity to intestinal helminth infections, the importance of chemokines has been neglected. As a chemokine with both chemoattractive properties and an ability to shape the quality of the adaptive immune response, CC chemokine ligand 2 (CCL2) was investigated as an attractive candidate for controlling resistance to these types of infection, which require highly polarized Th cell responses. We show here for the first time that CCL2 plays an important role in the development of resistance to infection by the gastrointestinal nematode Trichuris muris. Thus, in the absence of CCL2, worm expulsion does not occur, and the lymph node draining the site of infection becomes a Th1-promoting environment. Elevated levels of IL-12 are produced by polarizing APCs, and the composition of the APC environment itself is perturbed, with reduced numbers of macrophages.
Origin of Mannose-Binding Lectin-Associated Serine Protease (MASP)-1 and MASP-3 Involved in the Lectin Complement Pathway Traced Back to the Invertebrate, Amphioxus
Authors: Endo Yuichi , Nonaka Masaru , Saiga Hidetoshi , Kakinuma Yuji , Matsushita Akiko , Takahashi Minoru , Matsushita Misao , Fujita Teizo 
Published: April 2014

Abstract
Mannose-binding lectin-associated serine proteases (MASPs) are involved in complement activation through the lectin pathway. To elucidate the phylogenetic origin of MASP and a primordial complement system, we cloned two MASP cDNAs from amphioxus (Branchiostoma belcheri) of the cephalochordates, considered to be the closest relative of vertebrates. The two sequences, orthologues of mammalian MASP-1 and MASP-3, were produced by alternative processing of RNA from a single gene consisting of a common H chain-encoding region and two L chain-encoding regions, a structure which is similar to that of the human MASP1/3 gene. We also isolated two MASP genes from the ascidian Halocynthia roretzi (urochordates) and found that each of them consists simply of an H chain-encoding region and a single L chain-encoding region. The difference in structure between the ascidian MASP genes and the amphioxus/mammalian MASP genes suggests that a prototype gene was converted to the MASP1/3-type gene possessing two L chain-encoding regions at an early stage of evolution before the divergence of amphioxus. This conclusion is supported by the presence of MASP-1 and MASP-3 homologues in almost all vertebrates, as demonstrated by the cloning of novel cDNA sequences representing lamprey (cyclostomes) MASP-1 and Xenopus MASP-3. The ancient origin of MASP-1 and MASP-3 suggests that they have crucial functions common to all species which emerged after cephalochordates.
Retrocyclin, an Antiretroviral θ-Defensin, Is a Lectin
Authors: Wang Wei , Cole Alexander M. , Hong Teresa , Waring Alan J. , Lehrer Robert I. 
Published: April 2014

Abstract
θ-Defensins are circular octadecapeptides that contain an internal tridisulfide ladder. Because retrocyclin-1, an ancestral hominid θ-defensin, can protect human cells in vitro from infection by T- and M-tropic strains of HIV-1, we used surface plasmon resonance techniques to study its binding to glycoproteins and glycolipids implicated in HIV-1 entry. Retrocyclin-1 bound with high affinity to gp120 (Kd, 35.4 nM), CD4 (Kd, 31 nM), and galactosylceramide (Kd, 24.1 nM). Neither a circular form of retrocyclin without its tridisulfide ladder nor its β-hairpin precursor with these disulfides intact bound gp120 or CD4 effectively. Retrocyclin also bound fetuin, an extensively glycosylated protein, with high affinity, but it did not bind nonglycosylated gp120 or BSA. However, retrocyclin did bind to a neoglycoprotein, BSA, with covalently attached sugar residues. Experiments with glycosidase-treated fetuin, gp120, and CD4 revealed that both O-linked and N-linked sugars were used as binding sites. In a panel of retrocyclin variants, binding to immobilized gp120 and CD4 were highly correlated to each other and to the peptide’s ability to protect human PBMCs from infection by HIV-1. Although small, cysteine-rich antimicrobial peptides with lectin-like properties exist in plants, θ-defensins are the first such molecules to be identified in vertebrates. Retrocyclin’s ability to recognize and bind carbohydrate-containing surface molecules is integrally related to its ability to protect cells from HIV-1 infection.
CpG Oligodeoxynucleotides Protect Normal and SIV-Infected Macaques fromLeishmaniaInfection
Authors: Verthelyi Daniela , Gursel Mayda , Kenney Richard T. , Lifson Jeffrey D. , Liu Shuying , Mican Joan , Klinman Dennis M. 
Published: April 2014

AbstractOligodeoxynucleotides containing CpG motifs (CpG ODNs) mimic microbial DNA and activate effectors of the innate immune response, which limits the spread of pathogens and promotes an adaptive immune response. CpG ODNs have been shown to protect mice from infection with intracellular pathogens. Unfortunately, CpG motifs that optimally stimulate humans are only weakly active in mice, mandating the use of nonhuman primates to monitor the activity and safety of “human” CpG ODNs in vivo. This study demonstrates that CpG ODN treatment of rhesus macaques significantly reduces the severity of the lesions caused by a challenge with Leishmania. Leishmania superinfection is common in immunocompromised hosts, particularly those infected with HIV. This study shows that PBMCs from HIV-infected subjects respond to stimulation with CpG ODNs. To determine whether CpG ODNs can protect retrovirus-infected primates, SIV-infected macaques were treated with CpG ODNs and then challenged with Leishmania. Both lesion size and parasite load were significantly reduced in the CpG-treated animals. These findings support the clinical development of CpG ODNs as immunoprotective agents in normal and HIV-infected patients.
IL-1 Receptor Type 1 Gene-Deficient Mice Demonstrate an Impaired Host Defense Against Pneumococcal Meningitis
Authors: Zwijnenburg Petra J. G. , van der Poll Tom , Florquin Sandrine , Roord John J. , van Furth A. Marceline 
Published: April 2014

Abstract
The fatality rate associated with Streptococcus pneumoniae meningitis remains high despite adequate antibiotic treatment. IL-1 is an important proinflammatory cytokine, which is up-regulated in brain tissue after the induction of meningitis. To determine the role of IL-1 in pneumococcal meningitis we induced meningitis by intranasal inoculation with 8 × 104 CFU of S. pneumoniae and 180 U of hyaluronidase in IL-1R type I gene-deficient (IL-1R−/−) mice and wild-type mice. Meningitis resulted in elevated IL-1α and IL-1β mRNA and protein levels in the brain. The absence of an intact IL-1 signal was associated with a higher susceptibility to develop meningitis. Furthermore, the lack of IL-1 impaired bacterial clearance, as reflected by an increased number of CFU in cerebrospinal fluid of IL-1R−/− mice. The characteristic pleocytosis of meningitis was not significantly altered in IL-1R−/− mice, but meningitis was associated with lower brain levels of cytokines. The mortality was significantly higher and earlier in the course of the disease in IL-1R−/− mice. These results demonstrate that endogenous IL-1 is required for an adequate host defense in pneumococcal meningitis.
IL-12 Receptor β1 and Toll-Like Receptor 4 Increase IL-1β- and IL-18-Associated Myocarditis and Coxsackievirus Replication
Authors: Fairweather DeLisa , Yusung Susan , Frisancho Sylvia , Barrett Masheka , Gatewood Shannon , Steele Ronelle , Rose Noel R. 
Published: April 2014

AbstractTh1-type immune responses, mediated by IL-12-induced IFN-γ, protect the host from most viral infections. To investigate the role of IL-12 and IFN-γ on the development of Coxsackievirus B3 (CB3)-induced myocarditis, we examined the level of inflammation, viral replication, and cytokine production in IL-12Rβ1- and IFN-γ-deficient mice following CB3 infection. We report that IL-12Rβ1 deficiency results in decreased viral replication and inflammation in the heart, while IFN-γ deficiency exacerbates CB3 replication. Importantly, decreased IL-1β and IL-18 levels in IL-12Rβ1-deficient hearts correlated directly with decreased myocardial inflammation. Because IL-1β and IL-18 were associated with myocardial inflammation, we examined the effect of TLR4 deficiency on CB3 infection and myocarditis. We found that TLR4-deficient mice also had significantly reduced levels of myocarditis, viral replication, and IL-1β/IL-18, just as we had observed in IL-12Rβ1-deficient mice. This is the first report that TLR4 influences CB3 replication. These results show that IL-12Rβ1 and TLR4 exacerbate CB3 infection and myocarditis while IFN-γ protects against viral replication. The remarkable similarities between the effects of IL-12Rβ1 and TLR4 suggest that these receptors share common downstream pathways that directly influence IL-1β and IL-18 production, and confirm that IL-1β and IL-18 play a significant role in the pathogenesis of CB3-induced myocarditis. These findings have important implications not only for the pathogenesis of myocarditis, but for other autoimmune diseases triggered by viral infections.
Microsomal Prostaglandin E Synthase-1 Is a Major Terminal Synthase That Is Selectively Up-Regulated During Cyclooxygenase-2-Dependent Prostaglandin E2 Production in the Rat Adjuvant-Induced Arthritis Model
Authors: Claveau David , Sirinyan Mirna , Guay Jocelyne , Gordon Robert , Chan Chi-Chung , Bureau Yves , Riendeau Denis , Mancini Joseph A. 
Published: April 2014

Abstract
To better define the role of the various prostanoid synthases in the adjuvant-induced arthritis (AIA) model, we have determined the temporal expression of the inducible PGE synthase (mPGES-1), mPGES-2, the cytosolic PGES (cPGES/p23), and prostacyclin synthase, and compared with that of cyclooxygenase-1 (COX-1) and COX-2. The profile of induction of mPGES-1 (50- to 80-fold) in the primary paw was similar to that of COX-2 by both RNA and protein analysis. Quantitative PCR analysis indicated that induction of mPGES-1 at day 15 was within 2-fold that of COX-2. Increased PGES activity was measurable in membrane preparations of inflamed paws, and the activity was inhibitable by MK-886 to ≥90% with a potency similar to that of recombinant rat mPGES-1 (IC50 = 2.4 μM). The RNA of the newly described mPGES-2 decreased by 2- to 3-fold in primary paws between days 1 and 15 postadjuvant. The cPGES/p23 and COX-1 were induced during AIA, but at much lower levels (2- to 6-fold) than mPGES-1, with the peak of cPGES/p23 expression occurring later than that of COX-2 and PGE2 production. Prostacyclin (measured as 6-keto-PGF1α) was transiently elevated on day 1, and prostacyclin synthase was down-regulated at the RNA level after day 3, suggesting a diminished role of prostacyclin during the maintenance of chronic inflammation in the rat AIA. These results show that mPGES-1 is up-regulated throughout the development of AIA and suggest that it plays a major role in the elevated production of PGE2 in this model.
Mitochondrial Potential and Reactive Oxygen Intermediates in Antigen-Specific CD8+ T Cells During Viral Infection
Authors: Grayson Jason M. , Laniewski Nathan G. , Lanier J. Gibson , Ahmed Rafi 
Published: April 2014

Abstract
Following many viral infections, there are large expansions of Ag-specific CD8+ T cells. After viral clearance, mechanisms exist to ensure that the vast majority of effector cells undergo apoptosis. In studies of thymocyte apoptosis, loss of mitochondrial potential (ΔΨm) and excess production of reactive oxygen intermediates have been implicated as key events in cellular apoptosis. The purpose of the experiments presented in this work was to determine these parameters in Ag-specific CD8+ T cells during a physiological response such as viral infection. Using lymphocytic choriomeningitis virus infection of mice, we found that Ag-specific CD8+ effector T cells that had undergone recent TCR stimulation had an increased ΔΨm. These cells also had increased levels of superoxide. As these cells progressed through the contraction of the immune response, their potential decreased, but superoxide levels remained similar to naive cells. One of the consequences of reduced mitochondrial potential is membrane permeability and subsequent caspase activation. We examined both the enzymatic activity and levels of cleaved caspase 3, an effector caspase, and could only detect increased levels in Ag-specific CD8+ T cells on day 5 postinfection, a time point in which virus was still present. This contrasts with Ag-specific effector cells examined during the contraction phase that had no detectable caspase activity directly ex vivo. These data suggest that the apoptotic program begins earlier than previously expected on day 5, during the expansion phase.
Δ12-Prostaglandin J2, a Plasma Metabolite of Prostaglandin D2, Causes Eosinophil Mobilization from the Bone Marrow and Primes Eosinophils for Chemotaxis
Authors: Heinemann Akos , Schuligoi Rufina , Sabroe Ian , Hartnell Adele , Peskar Bernhard A. 
Published: April 2014

Abstract
PGD2, a major mast cell mediator, is a potent eosinophil chemoattractant and is thought to be involved in eosinophil recruitment to sites of allergic inflammation. In plasma, PGD2 is rapidly transformed into its major metabolite Δ12-PGJ2, the effect of which on eosinophil migration has not yet been characterized. In this study we found that Δ12-PGJ2 was a highly effective chemoattractant and inducer of respiratory burst in human eosinophils, with the same efficacy as PGD2, PGJ2, or 15-deoxy-Δ12,14-PGJ2. Moreover, pretreatment of eosinophils with Δ12-PGJ2 markedly enhanced the chemotactic response to eotaxin, and in this respect Δ12-PGJ2 was more effective than PGD2. Δ12-PGJ2-induced facilitation of eosinophil migration toward eotaxin was not altered by specific inhibitors of intracellular signaling pathways relevant to the chemotactic response, phosphatidylinositol 3-kinase (LY-294002), mitogen-activated protein kinase/extracellular signal-regulated kinase kinase (U-0126), or p38 mitogen-activated protein kinase (SB-202190). Desensitization studies using calcium flux suggested that Δ12-PGJ2 signaled through the same receptor, CRTH2, as PGD2. Finally, Δ12-PGJ2 was able to mobilize mature eosinophils from the bone marrow of the guinea pig isolated perfused hind limb. Given that Δ12-PGJ2 is present in the systemic circulation at relevant levels, a role for this PGD2 metabolite in eosinophil release from the bone marrow and in driving eosinophil recruitment to sites of inflammation appears conceivable.
IL-1-Driven Endogenous IL-10 Production Protects Against the Systemic and Local Acute Inflammatory Response Following Intestinal Reperfusion Injury
Authors: Souza Danielle G. , Guabiraba Rodrigo , Pinho Vanessa , Bristow Adrian , Poole Stephen , Teixeira Mauro M. 
Published: April 2014

Abstract
TNF-α release and action are central in the pathogenesis of the local and systemic inflammatory responses that occur after intestinal reperfusion. In this study we examined whether IL-1 participated in the cascade of events leading to TNF-α production and TNF-α-mediated injury following reperfusion of the ischemic superior mesenteric artery in rats. Blockade of the action of IL-1 by the use of anti-IL-1 antiserum or administration of IL-1R antagonist (IL-1ra), a natural antagonist of IL-1Rs, resulted in marked enhancement of reperfusion-associated tissue injury, TNF-α expression, and lethality. In contrast, there was marked decrease in IL-10 production. Facilitation of IL-1 action by administration of anti-IL-1ra, which antagonizes endogenous IL-1ra, or exogenous administration of rIL-1β suppressed reperfusion-induced tissue pathology, TNF-α production, and lethality, but increased IL-10 production. Exogenous administration of IL-10 was effective in preventing the increase in tissue or plasma levels of TNF-α, the exacerbated tissue injury, and lethality. An opposite effect was observed after treatment with anti-IL-10, demonstrating a role for endogenous production of IL-10 in modulating exacerbated reperfusion-associated tissue pathology and lethality. Finally, pretreatment with anti-IL-10 reversed the protective effect of IL-1β on reperfusion-associated lethality. Thus, IL-1 plays a major role in driving endogenous IL-10 production and protects against the TNF-α-dependent systemic and local acute inflammatory response following intestinal reperfusion injury.
Tyrosine Phosphorylation of I-κB Kinase α/β by Protein Kinase C-Dependent c-Src Activation Is Involved in TNF-α-Induced Cyclooxygenase-2 Expression
Authors: Huang Wei-Chien , Chen Jun-Jie , Inoue Hiroyasu , Chen Ching-Chow 
Published: April 2014

AbstractThe signaling pathway involved in TNF-α-induced cyclooxygenase-2 (COX-2) expression was further studied in human NCI-H292 epithelial cells. A protein kinase C (PKC) inhibitor (staurosporine), tyrosine kinase inhibitors (genistein and herbimycin A), or a Src kinase inhibitor (PP2) attenuated TNF-α- or 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced COX-2 promoter activity. TNF-α- or TPA-induced I-κB kinase (IKK) activation was also blocked by these inhibitors, which reversed I-κBα degradation. Activation of c-Src and Lyn kinases, two Src family members, was inhibited by the PKC, tyrosine kinase, or Src kinase inhibitors. The dominant-negative c-Src (KM) mutant inhibited induction of COX-2 promoter activity by TNF-α or TPA. Overexpression of the constitutively active PKCα (PKCα A/E) or wild-type c-Src plasmids induced COX-2 promoter activity, and these effects were inhibited by the dominant-negative c-Src (KM), NF-κB-inducing kinase (NIK) (KA), or IKKβ (KM) mutant. The dominant-negative PKCα (K/R) or c-Src (KM) mutant failed to block induction of COX-2 promoter activity caused by wild-type NIK overexpression. In coimmunoprecipitation experiments, IKKα/β was found to be associated with c-Src and to be phosphorylated on its tyrosine residues after TNF-α or TPA treatment. Two tyrosine residues, Tyr188 and Tyr199, near the activation loop of IKKβ, were identified to be crucial for NF-κB activation. Substitution of these residues with phenylalanines attenuated COX-2 promoter activity and c-Src-dependent phosphorylation of IKKβ induced by TNF-α or TPA. These data suggest that, in addition to activating NIK, TNF-α also activates PKC-dependent c-Src. These two pathways cross-link between c-Src and NIK and converge at IKKα/β, and go on to activate NF-κB, via serine phosphorylation and degradation of IκB-α, and, finally, to initiate COX-2 expression.
IFN-β Gene Deletion Leads to Augmented and Chronic Demyelinating Experimental Autoimmune Encephalomyelitis
Authors: Teige Ingrid , Treschow Alexandra , Teige Anna , Mattsson Ragnar , Navikas Vaidrius , Leanderson Tomas , Holmdahl Rikard , Issazadeh-Navikas Shohreh 
Published: April 2014

AbstractSince the basic mechanisms behind the beneficial effects of IFN-β in multiple sclerosis (MS) patients are still obscure, here we have investigated the effects of IFN-β gene disruption on the commonly used animal model for MS, experimental autoimmune encephalomyelitis (EAE). We show that IFN-β knockout (KO) mice are more susceptible to EAE than their wild-type (wt) littermates; they develop more severe and chronic neurological symptoms with more extensive CNS inflammation and demyelination. However, there was no discrepancy observed between wt and KO mice regarding the capacity of T cells to proliferate or produce IFN-γ in response to recall Ag. Consequently, we addressed the effect of IFN-β on encephalitogenic T cell development and the disease initiation phase by passive transfer of autoreactive T cells from KO or wt littermates to both groups of mice. Interestingly, IFN-β KO mice acquired a higher incidence and augmented EAE regardless of the source of T cells. This shows that the anti-inflammatory effect of endogenous IFN-β is predominantly exerted on the effector phase of the disease. Histopathological investigations of CNS in the effector phase revealed an extensive microglia activation and TNF-α production in IFN-β KO mice; this was virtually absent in wt littermates. This coincided with an increase in effector functions of T cells in IFN-β KO mice, as measured by IFN-γ and IL-4 production. We suggest that lack of endogenous IFN-β in CNS leads to augmented microglia activation, resulting in a sustained inflammation, cytokine production, and tissue damage with consequent chronic neurological deficits.