bluuebunny/crossref_metadata_2025_split huggingface dataset:
MHC Class II Antigen Processing in B Cells: Accelerated Intracellular Targeting of Antigens
Authors: Cheng Paul C. , Steele Carrie R. , Gu Lin , Song Wenxia , Pierce Susan K. 
Published: December 2022

AbstractProcessing and presentation by Ag-specific B cells is initiated by Ag binding to the B cell Ag receptor (BCR). Cross-linking of the BCR by Ag results in a rapid targeting of the BCR and bound Ag to the MHC class II peptide loading compartment (IIPLC). This accelerated delivery of Ag may be essential in vivo during periods of rapid Ag-driven B cell expansion and T cell-dependent selection. Here, we use both immunoelectron microscopy and a nondisruptive protein chemical polymerization method to define the intracellular pathway of the targeting of Ags by the BCR. We show that following cross-linking, the BCR is rapidly transported through transferrin receptor-containing early endosomes to a LAMP-1+, β-hexosaminadase+, multivesicular compartment that is an active site of peptide-class II complex assembly, containing both class II-invariant chain complexes in the process of invariant chain proteolytic removal as well as mature peptide-class II complexes. The BCR enters the class II-containing compartment as an intact mIg/Igα/Igβ complex bound to Ag. The pathway by which the BCR targets Ag to the IIPLC appears not to be identical to that by which Ags taken up by fluid phase pinocytosis traffick, suggesting that the accelerated BCR pathway may be specialized and potentially independently regulated.
CD94/NKG2-A Inhibitory Complex Blocks CD16-Triggered Syk and Extracellular Regulated Kinase Activation, Leading to Cytotoxic Function of Human NK Cells
Authors: Palmieri Gabriella , Tullio Valentino , Zingoni Alessandra , Piccoli Mario , Frati Luigi , Lopez-Botet Miguel , Santoni Angela 
Published: December 2022

AbstractThe CD94/NKG2-A complex is the inhibitory receptor for the nonclassical MHC class I molecule HLA-E on human NK cells. Here we studied the molecular mechanisms underlying the inhibitory activity of CD94/NKG2-A on NK cell functions by analyzing its interference on CD16-initiated signaling pathways involved in the control of cytolytic activity. Both tyrosine phosphorylation and activation of Syk kinase together with tyrosine phosphorylation of CD16 receptor ζ subunit are markedly inhibited by the coengagement of CD94/NKG2-A complex. As a downstream consequence, CD94/NKG2-A cross-linking impairs the CD16-induced activation of extracellular regulated kinases (ERKs), a pathway involved in NK cytotoxic function. The block of ERK activation is exerted at an early, PTK-dependent stage in the events leading to p21ras activation, as the CD16-induced tyrosine phosphorylation of Shc adaptor protein and the formation of Shc/Grb-2 complex are abrogated by CD94/NKG2-A simultaneous engagement. Our observations indicate that CD94/NKG2-A inhibits the CD16-triggered activation of two signaling pathways involved in the cytotoxic activity of NK cells. They thus provide molecular evidence to explain the inhibitory function of CD94/NKG2-A receptor on NK effector functions.
TNF-α-Mediated Apoptosis Is Initiated in Caveolae-Like Domains
Authors: Ko Young-Gyu , Lee Jae-Seon , Kang Young-Sun , Ahn Jung-Hyuck , Seo Jeong-Sun 
Published: December 2022

AbstractCaveolae-like domains (CLDs) have been hypothesized to mediate apoptosis, since they contain sphingomyelin and initiate the conversion of sphingomyelin to ceramide. To address whether CLDs are directly involved in apoptosis, CLDs from U937 cells were isolated, taking advantage of their detergent insolubility and low density. The CLDs contained alkaline phosphatase as well as many signaling molecules, including Fyn, protein kinase Cα, Raf-1, phospholipase Cγ1, and tyrosine phosphoproteins. Immunoblotting and immunofluorescent data showed that TNF receptor 1 colocalized with CD36 in CLDs, suggesting that TNF-α-initiated apoptosis occurs in CLDs. When cells were incubated with lipoprotein-deficient medium, the cholesterol concentration was greatly decreased in CLDs but not in other fractions, implying that the CLDs were selectively disrupted. In the CLD-disrupted cells, the surface expression of TNF receptor 1 and CD36 was significantly reduced. Analysis of cellular morphology, percent DNA fragmentation, DNA laddering, and caspase-3 activity showed that TNF-α-mediated apoptosis was blocked in CLD-disrupted cells, whereas anti-Fas-mediated apoptosis was not. Since Fas was not found in CLDs of Jurkat cells, apoptosis by Fas ligation might not require CLDs. Taken together, these data strongly imply that TNF-α-mediated apoptosis is initiated in CLDs.
IL-12 Induces IFN Regulating Factor-1 (IRF-1) Gene Expression in Human NK and T Cells
Authors: Galon Jérôme , Sudarshan Chitra , Ito Satochi , Finbloom David , O’Shea John J. 
Published: December 2022

AbstractIL-12 is a critical immunoregulatory cytokine that promotes cell-mediated immune responses and the differentiation of naive CD4+ cells to Th1 cells; however, relatively few IL-12 target genes have been identified. To better clarify the molecular basis of IL-12 action, we set out to characterize genes up-regulated by IL-12, first by contrasting IL-12- and IFN-α-inducible genes. We identified several genes up-regulated by IL-12, namely, MIP-1α, MIP-1β, IL-1RA, and IFN regulatory factor-1 (IRF-1). IRF-1 is a transcription factor regulated by IFNs that is also essential for Th1 responses. We demonstrated that IL-12 directly up-regulates IRF-1 to the same extent as IFN-α in normal human T cells and in NK cells. We showed that IL-12 had a direct effect on IRF-1, an effect not mediated indirectly by the induction of IFN-γ production. Furthermore, IL-2 and IL-12 synergistically induced IRF-1, whereas IFN-α and IL-12 did not. The participation of STAT4 in the regulation of IRF-1 was demonstrated in two ways. First, STAT4 was required for the IL-12-dependent transactivation of an IRF-1 reporter construct, and second, STAT4 binding to the IRF-1 promoter was shown using EMSA. In contrast to IL-12, no up-regulation of IRF-1 was found in IL-4-stimulated cells, and IL-4 did not block IL-12-dependent up-regulation of IRF-1. Therefore, IRF-1 may be an important contributor to IL-12 signaling, and we speculate that the defective IL-12 responses seen in IRF-1−/− mice might be attributable, in part, to the absence of this transcription factor.
Virus Infection Activates IL-1β and IL-18 Production in Human Macrophages by a Caspase-1-Dependent Pathway
Authors: Pirhonen Jaana , Sareneva Timo , Kurimoto Masashi , Julkunen Ilkka , Matikainen Sampsa 
Published: December 2022

AbstractMonocytes and macrophages play a significant role in host’s defense system, since they produce a number of cytokines in response to microbial infections. We have studied IL-1β, IL-18, IFN-α/β, and TNF-α gene expression and protein production in human primary monocytes and GM-CSF-differentiated macrophages during influenza A and Sendai virus infections. Virus-infected monocytes released only small amounts of IL-1β or IL-18 protein, whereas 7- and 14-day-old GM-CSF-differentiated macrophages readily produced these cytokines. Constitutive expression of proIL-18 was seen in monocytes and macrophages, and the expression of it was enhanced during monocyte/macrophage differentiation. Expression of IL-18 mRNA was clearly induced only by Sendai virus, whereas both influenza A and Sendai viruses induced IL-1β mRNA expression. Since caspase-1 is known to cleave proIL-1β and proIL-18 into their mature, active forms, we analyzed the effect of a specific caspase-1 inhibitor on virus-induced IL-1β and IL-18 production. The release of IL-1β and IL-18, but not that of IFN-α/β or TNF-α, was clearly blocked by the inhibitor. Our results suggest that the cellular differentiation is a crucial factor that affects the capacity of monocytes/macrophages to produce IL-1β and IL-18 in response to virus infections. Furthermore, the virus-induced activation of caspase-1 is required for the efficient production of biologically active IL-1β and IL-18.
Induction of Antitumor Immunity with Fas/APO-1 Ligand (CD95L)-Transfected Neuroblastoma Neuro-2a Cells
Authors: Shimizu Motomu , Fontana Adriano , Takeda Yasutaka , Yagita Hideki , Yoshimoto Takayuki , Matsuzawa Akio 
Published: December 2022

AbstractFas/Apo-1 (CD95)-Fas ligand (FasL) system has been implicated in the suppression and stimulation of immune responses. We examined the induction of antitumor immunity with neuroblastoma Neuro-2a cells transfected with FasL cDNA (Neuro-2a+FasL). Neuro-2a+FasL cells expressed FasL on the cell surface and secreted soluble FasL. Histologic and flow cytometric analyses revealed that Neuro-2a+FasL cells caused neutrophils to infiltrate into the injected site, resulting in strong inflammation. Neutrophil infiltration was inhibited by treatment with anti-FasL mAb and did not occur in Fas-deficient lpr mice. Normal syngeneic mice rejected Neuro-2a+FasL cells after the inflammation and acquired tumor-specific protective immunity. CD8+ T cells were responsible for the antitumor immunity. Neuro-2a+FasL cells formed tumors after far longer latency compared with mock-transfected Neuro-2a+Neo cells in nude mice, and immune competent mice rejected Neuro-2a cells but not sarcoma S713a cells when they were injected with Neuro-2a+FasL cells in a mixture. These results suggest that neutrophils attracted through the Fas-FasL system may impair tumor cells by inflammation at the initial step, followed by development of CD8+ T cell-dependent tumor-specific antitumor immunity, leading to complete eradication of tumor cells. Importantly, the treatment with Neuro-2a+FasL cells exhibited therapeutic efficacy against growing tumors.
Plasticity of Immune Responses Suppressing Parasitemia During AcutePlasmodium chabaudiMalaria
Authors: Weidanz William P. , Kemp Justin R. , Batchelder Joan M. , Cigel Francine K. , Sandor Matyas , Heyde Henri C. van der 
Published: December 2022

Abstractγδ T cells have a crucial role in cell-mediated immunity (CMI) against P. chabaudi malaria, but δ-chain knockout (KO) (δo/o) mice and mice depleted of γδ T cells with mAb cure this infection. To address the question of why mice deficient in γδ T cells resolve P. chabaudi infections, we immunized δo/o mice by infection with viable blood-stage parasites. Sera from infection-immunized mice were tested for their ability to protect JHo/o, δo/o double KO mice passively against P. chabaudi challenge infection. The onset of parasitemia was significantly delayed in mice receiving immune sera, compared with saline or uninfected serum controls. Immune sera were then fractionated into Ig-rich and Ig-depleted fractions by HPLC on a protein G column. Double KO mice were passively immunized with either fraction and challenged with P. chabaudi. The onset of parasitemia was significantly delayed in recipients of the Ig-rich fraction compared with recipients of the Ig-poor fraction of immune sera. We conclude that δo/o mice, which are unable to activate CMI against the parasite, suppress P. chabaudi infection by a redundant Ab-mediated process.
Alcohol (Ethanol) Inhibits IL-8 and TNF: Role of the p38 Pathway
Authors: Arbabi Saman , Garcia Iris , Bauer Gregory J. , Maier Ronald V. 
Published: December 2022

AbstractAcute ethanol (EtOH) intoxication has been identified as a risk factor for infectious complications in trauma and burn victims. However, the mechanism of this immune dysfunction has yet to be elucidated. The monocyte/macrophage production of cytokines, in particular IL-8 and TNF-α, is critical in the regulation of the acute inflammatory response to infectious challenge. IL-8 is a potent chemoattractant and activator of neutrophils. TNF-α, a proinflammatory cytokine, initiates expression of endothelial cell surface adhesion molecules and neutrophil migration. p38, a member of the mitogen-activated protein kinases, plays an important role in mediating intracellular signal transduction in endotoxin-induced inflammatory responses. We examined the effects of LPS and ethanol on p38 activation and the corresponding IL-8 and TNF-α production in human mononuclear cells. LPS-induced IL-8 and TNF-α production was inhibited in a similar pattern by pretreatment with either EtOH or SB202190 (1 μM), a specific inhibitor of p38 kinase. Western blot analysis, using a dual phospho-specific p38 mitogen-activated protein kinase Ab, demonstrated that EtOH pretreatment inhibited LPS-induced p38 activation. These results demonstrate that alcohol suppresses the normal host immune inflammatory response to LPS. This dysregulation appears to be mediated in part via inhibition of p38 activation. Inhibition of IL-8 and TNF-α production by acute EtOH intoxication may inhibit inflammatory focused neutrophil migration and activation and may be a mechanism explaining the increased risk of trauma- and burn-related infections.
IL-12, Independently of IFN-γ, Plays a Crucial Role in the Pathogenesis of a Murine Psoriasis-Like Skin Disorder
Authors: Hong Kenneth , Chu Alvina , Lúdvíksson Björn R. , Berg Ellen L. , Ehrhardt Rolf O. 
Published: December 2022

AbstractThe onset of acute psoriasis and the exacerbation of chronic psoriasis are often associated with a history of bacterial infection. We demonstrate that while only few scid/scid mice develop disease when CD4+CD45Rbhigh T cells are transferred alone, coadministration of LPS plus IL-12 or staphylococcal enterotoxin B into scid/scid mice 1 day after CD4+CD45Rbhigh T cell transfer greatly enhances disease penetrance and severity. Most importantly, the skin lesions induced by this method exhibit many of the histologic hallmarks observed in human psoriasis. Skin infiltrating CD4+ T cells were predominantly memory/effector cells (CD45Rblow) and exhibited a highly polarized Th1 phenotype. To test whether the development of pathogenic T cells was dependent on their production of IFN-γ, we transferred IFN-γ−/− CD4+CD45Rbhigh T cells into scid/scid or into T, B and NK cell-deficient scid/beige mice. Surprisingly, the incidence of psoriasis was similar to scid/scid animals that received IFN-γ+/+ T cells, although acanthosis of the skin was attenuated. In contrast, the development of psoriasis was abolished if anti-IL-12 mAb was administered on day 7 and 35 after T cell transfer. Skin-derived IFN-γ−/− inflammatory cells, but not cells from anti-IL-12-treated animals, secreted substantial amounts of TNF-α, suggesting that the inflammatory effect of IFN-γ−/− T cells may be partly exerted by TNF-α and that the therapeutic effect of anti-IL-12 may depend on its ability to down-regulate both TNF-α and IFN-γ. Overall, these results suggest that IL-12, independently of IFN-γ, is able to induce pathogenic, inflammatory T cells that are able to induce psoriasiform lesions in mice.
The Role of an Epithelial Neutrophil-Activating Peptide-78-Like Protein in Rat Adjuvant-Induced Arthritis
Authors: Halloran Margaret M. , Woods James M. , Strieter Robert M. , Szekanecz Zoltan , Volin Michael V. , Hosaka Shigeru , Haines G. Kenneth , Kunkel Steven L. , Burdick Marie D. , Walz Alfred , Koch Alisa E. 
Published: December 2022

Abstract
The chemokine, epithelial neutrophil-activating peptide-78 (ENA-78), is a potent neutrophil chemotaxin whose expression is increased in inflamed synovial tissue and fluid in human rheumatoid arthritis compared with osteoarthritis. Since ENA-78 has been implicated in the pathogenesis of RA, we examined the expression of an ENA-78-like protein during the development of rat adjuvant-induced arthritis (AIA). Using an ELISA assay, we found increased levels of antigenic ENA-78-like protein in the sera of AIA animals compared with control normal animals by day 7 postadjuvant injection. ENA-78-like protein levels continued to increase as AIA developed. ENA-78-like protein levels in joint homogenates were increased in AIA animals later in the development of the disease, by day 18 during maximal arthritis, compared with control animals. Expression of ENA-78-like protein in both the AIA serum and joint correlated with the progression of inflammation of the joints. Anti-human ENA-78 administered before disease onset modified the severity of AIA, while administration of anti-ENA-78 after clinical onset of AIA did not modify the disease. These data support a role for an ENA-78-like protein as an important chemokine in the progression and maintenance of AIA.
T Cell Autoimmunity in Ig Transgenic Mice
Authors: Shinde Sanjay , Gee Renelle , Santulli-Marotto Sandra , Bockenstedt Linda K. , Clarke Stephen H. , Mamula Mark J. 
Published: December 2022

AbstractAutoantibodies directed at a diverse group of proteins of the U1/Sm ribonucleoprotein (snRNP) are characteristic of systemic lupus erythematosus and are found in the MRL murine model of this disease. This study examines the role of transgenic B lymphocytes in the regulation of autoreactive T cells to the snRNP autoantigen. Transgenic mice were developed bearing an Ig heavy chain gene specific for the D protein component of murine snRNP. B lymphocytes in these mice are neither deleted nor anergic and are of an immature (heat-stable Aghigh) phenotype. T lymphocytes from anti-snRNP transgenic mice were examined using a recombinant form of the D protein of the murine snRNP complex. Our results revealed that transgenic anti-snRNP B cell APCs stimulated CD4 T cells from wild-type C57BL/6 and MRL lpr/lpr mice, while nonspecific APCs failed to stimulate CD4 T cells. This study demonstrates that autoreactive T cells are not deleted from wild-type mice, although their activation is facilitated by autoantigen-specific APCs. The snRNP-reactive T cells in C57BL/6 transgenic mice are tolerized, in contrast to those T cells from MRL lpr/lpr transgenic mice. These studies implicate a role for autoreactive B lymphocytes in the in vivo activation and/or diversification of autoreactive T cells.
Induction of MHC Class I Expression on Immature Thymocytes in HIV-1-Infected SCID-hu Thy/Liv Mice: Evidence of Indirect Mechanisms
Authors: Kovalev Grigoriy , Duus Karen , Wang Liping , Lee Robert , Bonyhadi Mark , Ho David , McCune Joseph M. , Kaneshima Hideto , Su Lishan 
Published: December 2022

AbstractThe SCID-hu Thy/Liv mouse and human fetal thymic organ culture (HF-TOC) models have been used to explore the pathophysiologic mechanisms of HIV-1 infection in the thymus. We report here that HIV-1 infection of the SCID-hu Thy/Liv mouse leads to the induction of MHC class I (MHCI) expression on CD4+CD8+ (DP) thymocytes, which normally express low levels of MHCI. Induction of MHCI on DP thymocytes in HIV-1-infected Thy/Liv organs precedes their depletion and correlates with the pathogenic activity of the HIV-1 isolates. Both MHCI protein and mRNA are induced in thymocytes from HIV-1-infected Thy/Liv organs, indicating induction of MHCI gene expression. Indirect mechanisms are involved, because only a fraction (&lt;10%) of the DP thymocytes were directly infected by HIV-1, although the majority of DP thymocytes are induced to express high levels of MHCI. We further demonstrate that IL-10 is induced in HIV-1-infected thymus organs. Similar HIV-1-mediated induction of MHCI expression was observed in HF-TOC assays. Exogenous IL-10 in HF-TOC induces MHCI expression on DP thymocytes. Therefore, HIV-1 infection of the thymus organ leads to induction of MHCI expression on immature thymocytes via indirect mechanisms involving IL-10. Overexpression of MHCI on DP thymocytes can interfere with thymocyte maturation and may contribute to HIV-1-induced thymocyte depletion.
IL-2 Plasmid Therapy of Murine Ovarian Carcinoma Inhibits the Growth of Tumor Ascites and Alters Its Cytokine Profile
Authors: Horton Holly M. , Dorigo Oliver , Hernandez Pepe , Anderson Deborah , Berek Jonathan S. , Parker Suezanne E. 
Published: December 2022

AbstractWe have evaluated whether i.p. murine ovarian tumors could be treated with an IL-2 plasmid DNA complexed with the cationic lipid, (±)-N-(2-hydroxyethyl)-N,N-dimethyl-2,3-bis(tetradecyloxy)-1-propanaminium bromide/dioleoylphosphatidylethanolamine (DMRIE/DOPE). Reporter gene studies were initially conducted in which mice bearing i.p. murine ovarian teratocarcinoma (MOT) were injected i.p. with reporter gene plasmid DNA (pDNA):DMRIE/DOPE. Histochemical analyses revealed that transfection occurred primarily in the tumor cells of the ascites, with only a minority of other ascitic cells or surrounding tissues transfected. IL-2 levels in the MOT ascites were determined after i.p. injection of either IL-2 pDNA:DMRIE/DOPE or recombinant IL-2 protein. IL-2 was detected in tumor ascites for up to 10 days after a single i.p. injection of IL-2 pDNA:DMRIE/DOPE, but was undetectable 24 h after a single i.p. injection of IL-2 protein. In an antitumor efficacy study, MOT tumor-bearing mice injected i.p. with IL-2 pDNA:DMRIE/DOPE on days 5, 8, and 11 after tumor cell implant had a significant inhibition of tumor ascites (p = 0.001) as well as a significant increase in survival (p = 0.008). A cytokine profile of the MOT tumor ascites revealed that mice treated with IL-2 pDNA:DMRIE/DOPE had an IL-2-specific increase in the levels of IFN-γ and GM-CSF. Taken together, these findings indicate that i.p. treatment of ovarian tumors with IL-2 pDNA:DMRIE/DOPE can lead to an increase in local IL-2 levels, a change in the cytokine profile of the tumor ascites, and a significant antitumor effect.
Role of APC in the Selection of Immunodominant T Cell Epitopes
Authors: Ma Chenglie , Whiteley Phyllis E. , Cameron Patricia M. , Freed Daniel C. , Pressey Alison , Chen Shiow-Ling , Garni-Wagner Beth , Fang Carol , Zaller Dennis M. , Wicker Linda S. , Blum Janice S. 
Published: December 2022

AbstractFollowing antigenic challenge, MHC-restricted T cell responses are directed against a few dominant antigenic epitopes. Here, evidence is provided demonstrating the importance of APC in modulating the hierarchy of MHC class II-restricted T cell responses. Biochemical analysis of class II:peptide complexes in B cells revealed the presentation of a hierarchy of peptides derived from the Ig self Ag. Functional studies of κ peptide:class II complexes from these cells indicated that nearly 20-fold more of an immunodominant epitope derived from κ L chains was bound to class II DR4 compared with a subdominant epitope from this same Ag. In vivo, T cell responses were preferentially directed against the dominant κ epitope as shown using Ig-primed DR4 transgenic mice. The bias in κ epitope presentation was not linked to differences in class II:κ peptide-binding affinity or epitope editing by HLA-DM. Rather, changes in native Ag structure were found to disrupt presentation of the immunodominant but not the subdominant κ epitope; Ag refolding restored κ epitope presentation. Thus, Ag tertiary conformation along with processing reactions within APC contribute to the selective presentation of a hierarchy of epitopes by MHC class II molecules.