bluuebunny/crossref_metadata_2025_split huggingface dataset:
Reconciling Repertoire Shift with Affinity Maturation: The Role of Deleterious Mutations
Authors: Shannon Michele , Mehr Ramit 
Published: January 2023

Abstract
The shift in Ab repertoire, from Abs dominating certain primary B cell responses to genetically unrelated Abs dominating subsequent “memory” responses, challenges the accepted paradigm of affinity maturation. We used mathematical modeling and computer simulations of the dynamics of B cell responses, hypermutation, selection, and memory cell formation to test hypotheses attempting to explain repertoire shift. We show that repertoire shift can be explained within the framework of the affinity maturation paradigm, only when we recognize the destructive nature of hypermutation: B cells with a high initial affinity for the Ag are less likely to improve through random mutations.
Stable Peptide Binding to MHC Class II Molecule Is Rapid and Is Determined by a Receptive Conformation Shaped by Prior Association with Low Affinity Peptides
Authors: Natarajan Sateesh K. , Assadi Masoumeh , Sadegh-Nasseri Scheherazade 
Published: January 2023

AbstractFormation of stable class II MHC/peptide complex involves conformational changes and proceeds via an intermediate. Although this intermediate complex forms and dissociates in minutes, its conversion to a stable complex is a very slow process, taking up to a few days to reach completion. Here, we investigate the different steps of this binding and demonstrate that the conformational changes necessary to generate a receptive molecule is the rate-determining slow step in the process, while formation of the stable MHC/peptide complex is very rapid. With HLA-DR1 as our model class II molecule, we first used low affinity variants of hemagglutinin peptide (HA306–318), which lack the principal anchor, to shape the conformation of the MHC and then studied the kinetics of stable binding of HA306–318 to such an induced conformation. We found that the apparent association rate of HA306–318 is equivalent to the dissociation rate of the low affinity peptide. A 4- to 18-fold enhancement in the binding rates of HA306–318 was observed depending on the dissociation rates of the low affinity peptides. These results establish that 1) formation of stable MHC/peptide complexes is very rapid and 2) prior binding of low affinity peptide induces a receptive conformation in MHC for efficient stable peptide binding. Furthermore, in the absence of any free peptide, this receptive molecule rapidly reverts to slow binding behavior toward the subsequently offered peptide. These results have important implications for the roles of low affinity MHC/peptide complexes in Ag presentation.
Inhibition of Matrix Metalloproteinases Prevents Allergen-Induced Airway Inflammation in a Murine Model of Asthma
Authors: Kumagai Katsunori , Ohno Isao , Okada Shinji , Ohkawara Yuichi , Suzuki Ko , Shinya Takashi , Nagase Hideaki , Iwata Kazushi , Shirato Kunio 
Published: January 2023

Abstract
Although matrix metalloproteinases (MMPs) have been reported to play crucial roles in the migration of inflammatory cells through basement membrane components in vitro, the role of MMPs in the in vivo accumulation of the cells to the site of inflammation in bronchial asthma is still obscure. In this study, we investigated the role of MMPs in the pathogenesis of bronchial asthma, using a murine model of allergic asthma. In this model, we observed the increase of the release of MMP-2 and MMP-9 in bronchoalveolar lavage fluids after Ag inhalation in the mice sensitized with OVA, which was accompanied by the infiltration of lymphocytes and eosinophils. Administration of tissue inhibitor of metalloproteinase-2 to airways inhibited the Ag-induced infiltration of lymphocytes and eosinophils to airway wall and lumen, reduced Ag-induced airway hyperresponsiveness, and increased the numbers of eosinophils and lymphocytes in peripheral blood. The inhibition of cellular infiltration to airway lumen was observed also with tissue inhibitor of metalloproteinase-1 and a synthetic matrix metalloproteinase inhibitor. These data suggest that MMPs, especially MMP-2 and MMP-9, are crucial for the infiltration of inflammatory cells and the induction of airway hyperresponsiveness, which are pathophysiologic features of bronchial asthma, and further raise the possibility of the inhibition of MMPs as a therapeutic strategy of bronchial asthma.
Cutting Edge: Phorbol Ester Induction of IFN-γ Receptors Leads to Enhanced DRα Gene Expression
Authors: Sakamoto Shuji , Nie Jing , Taniguchi Taketoshi 
Published: January 2023

Abstract
We observed that IFN-γ-inducible expression of the DRα gene was enhanced when THP-1 cells are differentiated into macrophage-like cells by phorbol ester treatment. Here, we observed that class II MHC trans-activator and STAT1α mRNA, mediators of the signaling cascade from the IFN-γ receptor to the DRα induction, were markedly increased by IFN-γ stimulation in phorbol ester-activated THP-1 cells; however, both mRNAs were not increased by phorbol ester treatment alone. Then, we demonstrated that the mRNA and proteins of the IFN-γ receptor α- and β-chains were amplified by phorbol ester treatment in THP-1 cells. Consequently, these results indicate that the enhancement of DRα gene expression by IFN-γ treatment in phorbol ester-activated THP-1 cells is due to the phorbol ester-induced up-regulation of IFN-γ receptor α- and β-chains. As a result, the amplification of STAT1α and the increment of class II MHC trans-activator results in enhancement of DRα expression.
The Functional Synergy Between IL-12 and IL-2 Involves p38 Mitogen-Activated Protein Kinase and Is Associated with the Augmentation of STAT Serine Phosphorylation
Authors: Gollob Jared A. , Schnipper Claudia P. , Murphy Erin A. , Ritz Jerome , Frank David A. 
Published: January 2023

Abstract
IL-12 and IL-2 can stimulate mitogen- or CD3-activated T cells to proliferate, produce IFN-γ, and kill tumor cells. The magnitude of these functional responses is greatly augmented when T cells are activated by the combination of IL-12 and IL-2. Although peripheral blood T cells are largely unresponsive to these cytokines without prior activation, a small subset of CD8+ T cells (CD8+CD18bright) is strongly activated by the combination of IL-12 and IL-2. In this report we show that the functional synergy between IL-12 and IL-2 in CD8+CD18bright T cells correlates with the activation of the stress kinases, p38 mitogen-activated protein (MAP) kinase and stress-activated protein kinase (SAPK)/Jun N-terminal kinase, but not with the activation of the extracellular signal-regulated kinases. The functional synergy between IL-2 and IL-12 is also associated with a prominent increase in STAT1 and STAT3 serine phosphorylation over that observed with IL-12 or IL-2 alone. By contrast, STAT tyrosine phosphorylation is not augmented over that seen with either cytokine alone. A specific inhibitor of p38 MAP kinase completely inhibits the serine phosphorylation of STAT1 and STAT3 induced by IL-12 and IL-2 and abrogates the functional synergy between IL-12 and IL-2 without affecting STAT tyrosine phosphorylation. This suggests that p38 MAP kinase may play an important role in regulating STAT serine phosphorylation in response to the combination of IL-12 and IL-2. Furthermore, these findings indicate that the optimal activation of T cells by IL-12 and IL-2 may depend on an interaction between the p38 MAP kinase and Janus kinase/STAT signaling pathways.
CD28 Costimulation Is Crucial for the Development of Spontaneous Autoimmune Encephalomyelitis
Authors: Oliveira-dos-Santos Antonio J. , Ho Alexandra , Tada Yoshifumi , Lafaille Juan J. , Tonegawa Susumu , Mak Tak W. , Penninger Josef M. 
Published: January 2023

Abstract
Multiple sclerosis (MS) is a severe central nervous system disease. Experimental autoimmune encephalomyelitis (EAE) mimics MS in mice. We report that spontaneous development of EAE in RAG-1-deficient mice transgenic for a myelin basic protein (MBP)-specific TCR (TgMBP+/RAG-1−/−) requires expression of the T cell costimulatory molecule CD28. Surprisingly, T cells from CD28−/−TgMBP+/RAG-1−/− mice proliferate and produce IL-2 in response to MBP1–17 peptide in vitro, excluding clonal anergy as the mechanism of CD28-regulated pathogenesis. Proliferation of autoaggressive T cells was dependent on the concentration of the MBP peptide, as was the development of MBP-induced EAE in CD28-deficient PL/J mice. These results provide the first genetic evidence that CD28 costimulation is crucial for MBP-specific T cell activation in vivo and the initiation of spontaneous EAE.
Modulation of Allospecific CTL Responses During Pregnancy in Equids: An Immunological Barrier to Interspecies Matings?
Authors: Baker Jessica M. , Bamford Anona I. , Antczak D. F. 
Published: January 2023

AbstractMaternal immune recognition of the developing conceptus in equine pregnancy is characterized by the strongest and most consistent alloantibody response described in any species, a response directed almost exclusively against paternal MHC class I Ags. This work investigated the cellular immune response to paternal MHC Ags in pregnant and nonpregnant horses and donkeys, and in horses carrying interspecies hybrid mule conceptuses. We observed profound decreases in classical, MHC-restricted, CTL activity to allogeneic paternal cells in peripheral blood lymphocytes from both horse mares and donkey jennets carrying intraspecies pregnancies, compared with cells from nonpregnant controls. This is the first evidence in a randomly bred species for a generalized systemic shift of immune reactivity away from cellular and toward humoral immunity during pregnancy. Surprisingly, mares carrying interspecies hybrid mule conceptuses did not exhibit this transient, pregnancy-associated decrease in CTL activity. The failure of interspecies pregnancy to down-regulate cellular immune responses may be a heretofore-unrecognized, subtle barrier to reproductive success between species.
Expression of CD1d2 on Thymocytes Is Not Sufficient for the Development of NK T Cells in CD1d1-Deficient Mice
Authors: Chen Yi-Hua , Wang Bin , Chun Taehoon , Zhao Lillian , Cardell Susanna , Behar Samuel M. , Brenner Michael B. , Wang Chyung-Ru 
Published: January 2023

Abstract
CD1 is an MHC class I-like molecule that has been conserved throughout mammalian evolution. Unlike MHC class I molecules, CD1 can present unique nonprotein antigens to T cells. The murine CD1 locus contains two highly homologous genes, CD1d1 and CD1d2. CD1d1 is essential for the development of a major subset of NK T cells that promptly secrete IL-4 following activation. However, the function of CD1d2 has not yet been demonstrated. In the present study, we examined the expression of CD1d2 in CD1d1-deficient (CD1d1°) mice with the anti-CD1 Ab 3H3. Unlike CD1d1, which is expressed by all lymphocytes, CD1d2 can be detected only on the surface of thymocytes. To determine whether CD1d2 can select a unique subset of NK T cells, we compared the remnant population of NK T cells in CD1d1° and CD1d1, CD1d2-double deficient (CD1d1°CD1d2°) mice. No significant difference in the number of NK T cells and cytokine secretion capacity can be detected between CD1d1° and CD1d1°CD1d2° mice, indicating that CD1d2 cannot substitute for CD1d1 in NK T cell development. The inability of CD1d2 to select NK T cells is not due to the structural constraints of CD1d2 since CD1d2-transfected cells can be recognized by both NK T cell hybridomas and freshly isolated NK T cells. Given the structural similarities, it is possible that the low levels of surface expression and limited tissue distribution of CD1d2 may prevent it from functioning in the selection and expansion of NK T cells.
Complex Conserved Organization of the Mammalian Leukemia Inhibitory Factor Gene: Regulated Expression of Intracellular and Extracellular Cytokines
Authors: Haines Bryan P. , Voyle Roger B. , Pelton Tricia A. , Forrest Regan , Rathjen Peter D. 
Published: January 2023

Abstract
Leukemia inhibitory factor (LIF) is a member of the IL-6 family of pleiotropic cytokines, which are extensively involved in modulating hematopoiesis and immunity. We have undertaken a detailed analysis of LIF genomic organization and gene transcription and investigated the proteins expressed from alternate transcripts. Previously unidentified LIF transcripts, containing alternate first exons spliced onto common second and third exons, were cloned from murine embryonic stem cells, human embryonal carcinoma cells, and primary porcine fibroblasts. Based on sequence homology and position within the genomic sequence, this confirmed the existence of the LIF-M transcript in species other than the mouse and identified a new class of transcript, designated LIF-T. Thus, a complex genomic organization of the LIF gene, conserved among eutherian mammals, results in the expression of three LIF transcripts (LIF-D, LIF-M, and LIF-T) differentially expressed from alternate promoters. The first exon of the LIF-T transcript contained no in-frame AUG, causing translation to initiate downstream of the secretory signal sequence at the first AUG in exon two, producing a truncated LIF protein that was localized within the cell. Enforced secretion of this protein demonstrated that it could act as a LIF receptor agonist. Regulated expression of biologically active intracellular and extracellular LIF cytokine could thus provide alternate mechanisms for the modulation of hematopoiesis and immune system function.
Dramatic Influence of Vβ Gene Polymorphism on an Antigen-Specific CD8+ T Cell Response In Vivo
Authors: Bour Hélène , Michielin Olivier , Bousso Philippe , Cerottini Jean-Charles , MacDonald H. Robson 
Published: January 2023

Abstract
According to recent crystallographic studies, the TCR-αβ contacts MHC class I-bound antigenic peptides via the polymorphic V gene-encoded complementarity-determining region 1β (CDR1β) and the hypervariable (D)J-encoded CDR3β and CDR3α domains. To evaluate directly the relative importance of CDR1β polymorphism on the fine specificity of T cell responses in vivo, we have taken advantage of congenic Vβa and Vβb mouse strains that differ by a CDR1 polymorphism in the Vβ10 gene segment. The Vβ10-restricted CD8+ T cell response to a defined immunodominant epitope was dramatically reduced in Vβa compared with Vβb mice, as measured either by the expansion of Vβ10+ cells or by the binding of MHC-peptide tetramers. These data indicate that Vβ polymorphism has an important impact on TCR-ligand binding in vivo, presumably by modifying the affinity of CDR1β-peptide interactions.
Vasoactive Intestinal Peptide and Pituitary Adenylate Cyclase-Activating Polypeptide Prevent Inducible Nitric Oxide Synthase Transcription in Macrophages by Inhibiting NF-κB and IFN Regulatory Factor 1 Activation
Authors: Delgado Mario , Munoz-Elias Ernesto J. , Gomariz Rosa P. , Ganea Doina 
Published: January 2023

AbstractHigh-output nitric oxide (NO) production from activated macrophages, resulting from the induction of inducible NO synthase (iNOS) expression, represents a major mechanism for macrophage cytotoxicity against pathogens. However, despite its beneficial role in host defense, sustained high-output NO production was also implicated in a variety of acute inflammatory diseases and autoimmune diseases. Therefore, the down-regulation of iNOS expression during an inflammatory process plays a significant physiological role. This study examines the role of two immunomodulatory neuropeptides, the vasoactive intestinal peptide (VIP) and the pituitary adenylate cyclase-activating polypeptide (PACAP), on NO production by LPS-, IFN-γ-, and LPS/IFN-γ-stimulated peritoneal macrophages and the Raw 264.7 cell line. Both VIP and PACAP inhibit NO production in a dose- and time-dependent manner by reducing iNOS expression at protein and mRNA level. VPAC1, the type 1 VIP receptor, which is constitutively expressed in macrophages, and to a lesser degree VPAC2, the type 2 VIP receptor, which is induced upon macrophage activation, mediate the effect of VIP/PACAP. VIP/PACAP inhibit iNOS expression and activity both in vivo and in vitro. Two transduction pathways appear to be involved, a cAMP-dependent pathway that preferentially inhibits IFN regulatory factor-1 transactivation and a cAMP-independent pathway that blocks NF-κB binding to the iNOS promoter. The down-regulation of iNOS expression, together with previously reported inhibitory effects on the production of the proinflammatory cytokines IL-6, TNF-α, and IL-12, and the stimulation of the anti-inflammatory IL-10, define VIP and PACAP as “macrophage deactivating factors” with significant physiological relevance.
A New Member of the Ig Superfamily and a V-ATPase G Subunit Are Among the Predicted Products of Novel Genes Close to the TNF Locus in the Human MHC
Authors: Neville Matt J. , Campbell R. Duncan 
Published: January 2023

Abstract
It is becoming increasingly apparent that many of the genes in the class III region of the human MHC encode proteins involved in the immune and inflammatory responses. Furthermore, genetic studies have indicated that genes within the class III region, particularly the telomeric segment containing the TNF gene, could contribute to susceptibility to diseases of immune-related etiology. We have sequenced an 82-kb segment of DNA around the TNF gene to identify candidate disease susceptibility genes in this region. The 10 known genes in this region have been precisely positioned with the order allograft inflammatory factor 1, G1, 1C7, leukocyte-specific transcript 1 (B144), lymphotoxin B, TNF, lymphotoxin A, NB6, IKBL, BAT1 (centromere to telomere), and their genomic structures have been defined. Comparison of the G1 genomic region with previously described cDNA and genomic sequences, together with the results of reverse transcriptase-PCR, indicates that three alternative transcripts, G1, allograft inflammatory factor 1, and IFN-γ-responsive transcript, are all derived from this gene. The completion of the sequence of 1C7 (D6S2570) has revealed that this gene encodes a putative novel member of the Ig superfamily. A number of alternatively spliced transcripts of 1C7 were identified by reverse transcriptase-PCR, all of which are expressed in immune-related cell lines. Alternative splicing within the Ig domain-encoding region was seen to result in possible set switching between an IgV domain and an IgC2 domain. Lastly, a previously unidentified gene, homologous to a number of V-ATPase G subunits, has been located 1 kb telomeric of IKBL.
The Origin and Function of Soluble CD14 in Experimental Bacterial Meningitis
Authors: Cauwels Anje , Frei Karl , Sansano Sebastiano , Fearns Colleen , Ulevitch Richard , Zimmerli Werner , Landmann Regine 
Published: January 2023

AbstractMurine experimental meningitis models induced by either Escherichia coli LPS, live Streptococcus pneumoniae, or Listeria monocytogenes were used to study the origin and potential function of soluble CD14 (sCD14) in the brain during bacterial meningitis. Whereas intracerebral infection caused only a minor and/or transient increase of sCD14 levels in the serum, dramatically elevated concentrations of sCD14 were detected in the cerebrospinal fluid. Reverse-transcriptase PCR and FACS analysis of the leukocytes invading the subarachnoid compartment revealed an active amplification of CD14 transcription and concomitant surface expression. These findings were confirmed by in situ hybridization and immunohistochemical analysis. In contrast, parenchymal astrocytes and microglial cells were shown not to significantly contribute to the elevated levels of sCD14. Simultaneous intracerebral inoculation of rsCD14 and S. pneumoniae resulted in a markedly increased local cytokine response. Taken together, these data provide the first evidence that sCD14 can act as an inflammatory co-ligand in vivo. Thus, during bacterial meningitis, sCD14 is massively released by intrathecal leukocytes, and the sCD14 found in the cerebrospinal fluid can play an important role in the pathogenesis of this disease.
CD14 Plays No Major Role in Shock Induced by Staphylococcus aureus but Down-Regulates TNF-α Production
Authors: Haziot Alain , Hijiya Naoki , Schultz Karine , Zhang Fan , Gangloff Sophie C. , Goyert Sanna M. 
Published: January 2023

Abstract
Recent in vitro studies have suggested that CD14, a major receptor for LPS, may also be a receptor for cell wall components of Gram-positive bacteria and thus play a role in Gram-positive shock. To analyze the in vivo role of CD14 in responses to Gram-positive bacteria, CD14-deficient and control mice were injected with Staphylococcus aureus, and the effects on lethality, bacterial clearance, and production of cytokines were analyzed. Survival of CD14-deficient and control mice did not differ significantly after administration of various doses of either unencapsulated or encapsulated S. aureus; furthermore, mice in both groups displayed similar symptoms of shock. In addition, inflammatory cytokines such as TNF-α and IL-6 were readily detectable in the serum of CD14-deficient mice injected with live or antibiotic-killed S. aureus. Surprisingly, the serum concentration of TNF-α in CD14-deficient mice was at least threefold higher than in control mice after injection of either unencapsulated or encapsulated S. aureus, suggesting that CD14 down-regulates TNF-α. A similar increase in serum TNF-α occurred when CD14-deficient animals were injected with gentamicin-killed bacteria even though no symptoms of shock were observed. These studies indicate that CD14, in contrast to its key function in responses to the Gram-negative bacterium, Escherichia coli 0111, does not play a prominent role in septic shock induced by S. aureus, and that the symptoms of S. aureus shock are not due solely to TNF-α.
Inflammation Alone Evokes the Response of a TCR-Invariant Mouse γδ T Cell Subset
Authors: Mukasa Akiko , Born Willi K. , O’Brien Rebecca L. 
Published: January 2023

AbstractWhether γδ T lymphocytes respond to microbial Ags or to inducible host Ags remains a matter of controversy. Using several different disease models and mouse strains, we and others have seen that Vγ6/Vδ1 γδ T cells preferentially increase among the γδ T cells infiltrating inflamed tissues. However, it was not clear whether bacteria are necessary to bring about this response. Therefore, we have reexamined this question using a disease model in which inflammation is induced by a purely autoimmune process involving no bacteria, bacterial products, or other foreign material: testicular cell-induced autoimmune orchitis. Using this model we found that γδ T cells were still plentiful among the infiltrating T lymphocytes, being 9- to 10-fold more prevalent than in spleen, and that Vγ6/Vδ1+ cells again represented the predominant γδ T cell type. This finding shows that the response of the Vγ6/Vδ1+ subset does not, in fact, depend upon the presence of bacteria or bacterial products. The stimulus triggering the response of the Vγ6/Vδ1 γδ T cells appears to be neither foreign nor organ-specific in origin, but instead consists of a self-derived host Ag or signal induced during the inflammatory process.