bluuebunny/crossref_metadata_2025_split huggingface dataset:
Enhanced B-1 Cell Development, But Impaired IgG Antibody Responses in Mice Deficient in Secreted IgM
Authors: Boes Marianne , Esau Christine , Fischer Michael B. , Schmidt Tara , Carroll Michael , Chen Jianzhu 
Published: January 2023

Abstract
The role of endogenous natural IgM in promoting the adaptive Ab response was investigated in newly constructed mutant mice in which B cells do not secrete IgM but still express surface IgM and IgD and undergo class switching to express other Ig isotypes. While the mutant mice had relatively normal numbers of conventional B (B-2) cells in all tissues examined, unexpectedly, B-1 cells in the peritoneum and spleen were approximately threefold more abundant. The elevated levels of B-1 cells were already detectable at 4 wk of age and were stably maintained throughout life. The levels of serum IgG2a, IgG3, and IgA were also elevated in the mutant mice at an early age. IgG2a response to a T cell-independent Ag was augmented, whereas IgG Ab responses to suboptimal doses of a T cell-dependent Ag were impaired. The latter defect was associated with fewer splenic germinal centers, impaired Ab affinity maturation, and less Ag trapping on follicular dendritic cells. Together, these findings demonstrate a physiologic role of natural IgM in the feedback regulation of B-1 cell development, the regulation of IgG2a production, and the promotion of efficient B-2 cell Ab responses.
Dissociation of Proteasomal Degradation of Biosynthesized Viral Proteins from Generation of MHC Class I-Associated Antigenic Peptides
Authors: Antón Luis C. , Snyder Heidi L. , Bennink Jack R. , Vinitsky Alexander , Orlowski Marian , Porgador Angel , Yewdell Jonathan W. 
Published: January 2023

AbstractTo study the role of proteasomes in Ag presentation, we analyzed the effects of proteasome inhibitors Cbz-Leu-Leu-Leucinal and lactacystin on the ability of mouse fibroblast cells to present recombinant vaccinia virus gene products to MHC class I-restricted T cells. The effects of the inhibitors depended on the determinant analyzed. For influenza virus nucleoprotein (NP), presentation of the immunodominant Kk-restricted determinant (NP50–57) was marginally inhibited, whereas presentation of the immunodominant Kd-restricted determinant (NP147–155) was enhanced, particularly by lactacystin. Biochemical purification of peptides confirmed that lactacystin enhanced the generation of Kd-NP147–155 complexes fourfold. Lactacystin also enhanced the recovery of one Kd-restricted vaccinia virus determinant from HPLC fractions, while inhibiting recovery of another. The inhibitors were used at sufficient concentrations to block presentation of biosynthesized full-length OVA and to completely stabilize a rapidly degraded chimeric ubiquitin-NP fusion protein. Strikingly, presentation of antigenic peptides from this protein was unaffected by proteasome inhibitors. We also observed that proteasome inhibitors induced expression of cytosolic and endoplasmic reticulum stress-responsive proteins. These data demonstrate first that the processes of protein degradation and generation of antigenic peptides from cytosolic proteins can be dissociated, and second that effects of proteasome inhibitors on Ag presentation may reflect secondary effects on cellular metabolism.
Staphylococcus aureus-Induced Septic Arthritis and Septic Death Is Decreased in IL-4-Deficient Mice: Role of IL-4 as Promoter for Bacterial Growth
Authors: Hultgren Olof , Kopf Manfred , Tarkowski Andrzej 
Published: January 2023

Abstract
Lack of IL-4 has been shown to be protective in some experimental models of infectious diseases in mice such as cutaneous leishmaniasis. At the same time IL-4, together with other Th2 cytokines, including IL-10 and IL-13, is known as an anti-inflammatory cytokine with the potential to down-regulate proinflammatory cytokine production. To investigate the role of IL-4 in experimental Staphylococcus aureus-induced and T lymphocyte-mediated arthritis, IL-4-deficient C57BL/6 mice (IL-4−/−) and their congenic controls (IL-4+/+) were inoculated with a toxic shock syndrome toxin-1-producing S. aureus strain. In IL-4+/+ mice, arthritis peaked 14 days after bacterial inoculation, whereas, at that time, IL-4−/− mice displayed significantly less frequent (p &lt; 0.05) joint inflammation. Paralleling lower frequency of arthritis, IL-4-deficient mice showed a decreased bacterial burden in joints (p = 0.014) and kidneys (p = 0.029), as well as lower infection-triggered weight decrease and mortality. In vitro, IL-4 inhibited intracellular killing of S. aureus in infected macrophages, without affecting phagocytosis. This finding may explain the enhanced staphylococcal clearance observed in IL-4−/− mice in vivo. Our results suggest that IL-4 and IL-4-dependent Th2 responses promote septic arthritis and sepsis-related mortality by inhibition of bacterial clearance during S. aureus infection.
Quercetin Sensitizes RBL-2H3 Cells to Polybasic Mast Cell Secretagogues Through Increased Expression of Gi GTP-Binding Proteins Linked to a Phospholipase C Signaling Pathway
Authors: Senyshyn Jan , Baumgartner Rudolf A. , Beaven Michael A. 
Published: January 2023

AbstractPolybasic secretagogues such as mastoparan, compound 48/80, substance P, and somatostatin stimulate secretion in rat peritoneal mast cells through direct activation of the heterotrimeric G protein, Gi-3. Cultured RBL-2H3 mast cells do not normally respond to these secretagogues, but, as reported here, they do so after prolonged exposure to the kinase inhibitor, quercetin. This inhibitor, which causes phenotypic changes in RBL-2H3 cells, induces a substantial increase (more than sevenfold) in the expression of α subunits of the pertussis toxin-sensitive G proteins, Gi-2 and Gi-3. Compound 48/80-induced secretion is associated with transient hydrolysis of phosphoinositides and a transient increase in cytosolic calcium ions. These responses are inhibited by pertussis toxin, and in addition, secretion is blocked by calcium chelation and the protein kinase C inhibitor, Ro31-7549. These results delineate a pathway for compound 48/80-induced secretion in mast cells via Gi protein(s), phospholipase C, calcium, and protein kinase C. The results also imply that phospholipase C, most likely phospholipase Cβ3, can be transiently activated in RBL-2H3 cells by subunits of Gi proteins to induce cellular responses.
Killer Cell Inhibitory Receptors for MHC Class I Molecules Regulate Lysis of Melanoma Cells Mediated by NK cells, γδ T Cells, and Antigen-Specific CTL
Authors: Bakker Alexander B. H. , Phillips Joseph H. , Figdor Carl G. , Lanier Lewis L. 
Published: January 2023

AbstractNK cells and T cells express killer cell inhibitory receptors (KIR) recognizing polymorphic MHC class I molecules. Although prior studies have established that MHC class I can protect normal and transformed hematopoietic cells from NK cell lysis, the role of MHC class I on the recognition of solid tumors has been controversial. In this study, we investigated whether interactions of KIR with their ligands on melanoma tumor cells could inhibit tumor cell lysis by NK and γδ T cell clones. Ligation of the NK cell receptor KIR3DL1 by HLA-Bw4 allotypes resulted in inhibition of cytotoxicity against HLA-B*4403-transfected melanomas as well as against melanomas endogenously expressing HLA-Bw4 allotypes. Similarly, interactions of KIR2DL2 or KIR2DL3 (KIR2DL2/3) with HLA-Cw3-related allotypes on melanomas resulted in decreased tumor cell lysis. We also investigated whether signaling via KIR affected melanoma recognition by CTL. Introduction of KIR3DL1 molecules into HLA-A*0201-restricted gp100-specific CTL resulted in inhibition of lysis of gp100+ melanomas co-expressing HLA-A*0201 and HLA-Bw4 allotypes. These results suggest that disrupting interactions of KIR with their ligands on tumor cells in vivo may enhance antitumor responses mediated by both innate and adaptive immune effector cells.
Perforin and IFN-γ Are Involved in the Antitumor Effects of Antibody-Targeted Superantigens
Authors: Rosendahl Alexander , Kristensson Karin , Hansson Johan , Riesbeck Kristian , Kalland Terje , Dohlsten Mikael 
Published: January 2023

Abstract
The bacterial superantigen staphylococcal enterotoxin A (SEA) is a potent inducer of cytokine production and cytotoxic T cell responses. To target a T cell attack against tumor cells we have genetically engineered a fusion protein of SEA and the Fab part of the tumor-reactive mAb C215. Injection of this Fab-SEA fusion protein to mice carrying lung metastases of the poorly immunogenic B16 melanoma transfected with the C215 Ag resulted in infiltration of cytokine-producing T cells, perforin-containing CTL, and a marked tumor elimination. Fab-SEA therapy induced substantial levels of IFN-γ and TNF-α in serum. In the present study we have characterized the molecular mechanisms of the antitumor effect induced by Fab-SEA treatment in vivo. Neutralization of cytokines by specific Abs demonstrated a major role for IFN-γ in the suppression of tumor growth. In addition, a minor contribution of TNF-α was recorded. Injections of Fab-SEA into normal mice induced strong CTL activity but failed to promote cytotoxic function in perforin knockout mice. Also, a markedly reduced therapy was noted in perforin knockout mice, implicating a role for CTL in Fab-SEA-mediated tumor eradication. The data suggest that Fab-SEA-targeted T cells may suppress tumor growth by both perforin-dependent cytotoxicity and local release of cytokines such as IFN-γ. The latter mechanism may have an important role in cytostatic effects against Ag-negative bystander tumor cells.
1,25-Dihydroxyvitamin D3 Is a Positive Regulator for the Two Anti-Encephalitogenic Cytokines TGF-β1 and IL-4
Authors: Cantorna Margherita T. , Woodward William D. , Hayes Colleen E. , DeLuca Hector F. 
Published: January 2023

AbstractPreviously we demonstrated that 1,25-dihydroxyvitamin D3 blocks the progression of relapsing encephalomyelitis. We now propose that 1,25-dihydroxyvitamin D3 blocks these autoimmune symptoms by stimulating the differentiation and/or function of cells that inhibit the encephalitogenic process. To support this belief, we have found that 1,25-dihydroxyvitamin D3 administration to mice increases IL-4 transcripts by 3- to 25-fold and TGF-β1 transcripts by 4- to 24-fold. Similarly, IL-4 and TGF-β1 transcripts were higher in the central nervous system of 1,25-dihydroxyvitamin D3-treated mice compared with controls. The number of cells recoverable from the lymph nodes of 1,25-dihydroxyvitamin D3-treated mice was only 50% that of controls. Overall, 1,25-dihydroxyvitamin D3 treatment causes a net loss in the total number of lymphocytes while the number of IL-4 and TGF-β1 transcripts increased. The systemic and local increase in the expression of these two anti-inflammatory cytokines by 1,25-dihydroxyvitamin D3 may be responsible for the ability of this drug to block encephalomyelitis.
Fas Ligand-Induced Apoptosis of Infected Human Macrophages Reduces the Viability of IntracellularMycobacterium tuberculosis
Authors: Oddo Mauro , Renno Toufic , Attinger Antoine , Bakker Talitha , MacDonald H. Robson , Meylan Pascal R. A. 
Published: January 2023

AbstractMycobacterium tuberculosis-specific cytolytic activity is mediated mostly by CD4+CTL in humans. CD4+CTL kill infected target cells by inducing Fas (APO-1/CD95)-mediated apoptosis. We have examined the effect of Fas ligand (FasL)-induced apoptosis of human macrophages infected in vitro with M. tuberculosis on the viability of the intracellular bacilli. Human macrophages expressed Fas and underwent apoptosis after incubation with soluble recombinant FasL. In macrophages infected either with an attenuated (H37Ra) or with a virulent (H37Rv) strain of M. tuberculosis, the apoptotic death of macrophages was associated with a substantial reduction in bacillary viability. TNF-induced apoptosis of infected macrophages was coupled with a similar reduction in mycobacterial viability, while the induction of nonapoptotic complement-induced cell death had no effect on bacterial viable counts. Infected macrophages also showed a reduced susceptibility to FasL-induced apoptosis correlating with a reduced level of Fas expression. These data suggest that apoptosis of infected macrophages induced through receptors of the TNF family could be an immune effector mechanism not only depriving mycobacteria from their growth environment but also reducing viable bacterial counts by an unknown mechanism. On the other hand, interference by M. tuberculosis with the FasL system might represent an escape mechanism of the bacteria attempting to evade the effect of apoptosis.
Cloning and Characterization of Mouse Vascular Adhesion Protein-1 Reveals a Novel Molecule with Enzymatic Activity
Authors: Bono Petri , Salmi Marko , Smith David J. , Jalkanen Sirpa 
Published: January 2023

Abstract
Human vascular adhesion protein-1 (VAP-1) is a sialylated endothelial cell adhesion molecule mediating the initial L-selectin-independent interactions between lymphocytes and endothelial cells in man. In this work we cloned and characterized mouse VAP-1 (mVAP-1) and produced an anti-mVAP-1 mAb against a recombinant mVAP-1 fusion protein. The isolated cDNA encodes a novel 84.5-kDa mouse molecule. The anti-mVAP-1 mAb stained high endothelial venules in peripheral lymph nodes, and smooth muscle cells and lamina propria vessels in gut. During immunoblotting, this anti-mVAP-1 mAb recognized a 110/220-kDa Ag, suggesting that mVAP-1 is a dimer. Since mVAP-1 has significant sequence identity to members of a family of enzymes called the copper-containing amine oxidases, we showed that mVAP-1 possesses monoamine oxidase activity. Thus, mVAP-1 is the first mouse membrane-bound amine oxidase identified at the molecular level. Based on the 83% identity between the isolated cDNA and human VAP-1 cDNA, the expression pattern, the molecular mass, and the enzyme activity against monoamines, the cloned molecule represents a mouse homologue of human VAP-1. Cloning of mVAP-1 provides a valuable tool for in vivo studies of the significance of VAP-1 for lymphocyte-endothelial cell interactions and of the possible relationship between leukocyte adhesion and amine oxidase activity.
Stromal Cell-Independent Maturation of IL-7-Responsive Pro-B Cells
Authors: Ray Robert J. , Stoddart Angela , Pennycook Jacqueline L. , Huner H. Ozgur , Furlonger Caren , Wu Gillian E. , Paige Christopher J. 
Published: January 2023

AbstractThe proliferation, survival, and differentiation of B cell progenitors in primary hematopoietic tissues depends on extracellular signals produced by stromal cells within the microenvironment. IL-7 is a stromal-derived growth factor that plays a crucial role in B lineage development. We have shown that in the presence of IL-7, pro-B cells proliferate and differentiate to a stage in which they are responsive to stromal cells and LPS, leading to terminally differentiated IgM-secreting plasma cells. In this report, we examine in detail the role of stromal cells in the transition from the IL-7-responsive pro-B cell stage to the mature LPS-responsive B cell stage. We demonstrate that this transition fails to occur, even in the presence of stromal cells and LPS, if constant exposure to IL-7 is maintained. The transition from the large pro-B cell stage to the small cμ+ pre-B cell stage occurs independent of stromal cells. Moreover, the “stromal cell-dependent” maturation that occurs subsequent to the expression of surface IgM leading to responsiveness to B cell mitogens can also be accomplished in the absence of stromal cells if pre-B cells are cultured in proximity to each other or at high cell concentrations. Together these results suggest that stromal cells mediate B cell differentiation by providing the necessary growth requirements (i.e., IL-7) to sustain the development of pre-B cells. The progeny of these pre-B cells can then differentiate through as yet unidentified homotypic interactions, leading to the production of LPS-responsive B cells.
Lack of Both Types 1 and 2 Cytokines, Tissue Inflammatory Responses, and Immune Protection During Pulmonary Infection byMycobacterium bovisBacille Calmette-Guérin in IL-12-Deficient Mice
Authors: Wakeham Julia , Wang Jun , Magram Jeanne , Croitoru Kenneth , Harkness Robin , Dunn Pamela , Zganiacz Anna , Xing Zhou 
Published: January 2023

AbstractUnderstanding of key cytokines and the nature of protective immune responses in pulmonary mycobacterial diseases remains a task of paramount importance. In this study, both wild-type (wt) and IL-12-deficient (IL-12−/−) mice were infected by airways inoculation of live Mycobacterium bovis bacille Calmette-Guérin (BCG). The type 1 cytokines IL-12, IFN-γ, and TNF-α, but not the type 2 cytokines IL-4 and granulocyte macrophage (GM)-CSF, markedly increased in the lung and peripheral blood of wt mice postinfection, which resulted in the development of intense granulomatous responses and the effective control of mycobacterial infection in the lung. In contrast, IL-12−/− mice demonstrated a lack of both types 1 and 2 cytokines in the lung and blood and a severely impaired tissue immune-inflammatory response lacking not only macrophages and neutrophils but CD4 and CD8 T cells and NK cells in the lung throughout the entire course of study. Total lung mononuclear cells isolated from these mice, in contrast to wt mice, had an impaired recall immune response to Ag challenge in vitro. These impaired responses resulted in an uncontrolled local growth and systemic spread of bacilli. Our findings reveal that IL-12 plays an irreplaceable role in the initiation of Th1 responses, and the loss of its function cannot be compensated for by alternative mechanisms in the lung. This cytokine, together with IFN-γ and TNF-α, and granulomatous inflammation are critically required for the effective control of pulmonary mycobacterial infection. Our results also indicate that the absence of type 1 cytokines does not necessarily favor a Th2 response.
Humanization and Pharmacokinetics of a Monoclonal Antibody with Specificity for Both E- and P-Selectin
Authors: He Xing-Yue , Xu Zhenghai , Melrose Jennifer , Mullowney Alison , Vasquez Maximiliano , Queen Cary , Vexler Vladimir , Klingbeil Corine , Co Man Sung , Berg Ellen L. 
Published: January 2023

Abstract
E- and P-selectin (CD62E and CD62P) are cell adhesion molecules that mediate leukocyte-endothelial cell and leukocyte-platelet interactions and are involved in leukocyte recruitment during inflammation. We previously developed a murine mAb, EP-5C7 (or mEP-5C7), that binds and blocks both E- and P-selectin. When used in humans, murine mAbs have short circulating half-lives and generally induce potent human anti-mouse Ab responses. We therefore engineered a humanized, complementarity determining region-grafted version of mEP-5C7 incorporating human γ4 heavy and κ light chain constant regions (HuEP5C7.g4). HuEP5C7.g4 retains the specificity and avidity of mEP-5C7, binding to human E- and P-selectin but not to human L-selectin, and blocking E- and P-selectin-mediated adhesion. Surprisingly, when administered to rhesus monkeys, HuEP5C7.g4 was eliminated from the circulation very rapidly, even faster than the original murine Ab. To isolate the cause of the short serum half-life of HuEP5C7.g4, several Ab variants were constructed. A chimeric IgG4 Ab was made by replacing the humanized V regions with murine V regions. A humanized IgG2 Ab, HuEP5C7.g2, was also made by replacing the human γ4 with a γ2 constant region. Results from pharmacokinetic studies in rhesus monkeys demonstrated that the chimeric IgG4 is also rapidly eliminated rapidly from serum, similar to the humanized IgG4 Ab, while the humanized IgG2 Ab displays a long circulation half-life, typical of human Abs.
Opposite CD4/CD8 Lineage Decisions of CD4+8+ Mouse and Rat Thymocytes to Equivalent Triggering Signals: Correlation with Thymic Expression of a Truncated CD8α Chain in Mice But Not Rats
Authors: Mitnacht Rita , Bischof Astrid , Torres-Nagel Nora , Hünig Thomas 
Published: January 2023

Abstract
Unselected CD4+8+ rat thymocytes, generated in vitro from their direct precursors, are readily converted to functional TCRhigh T cells by stimulation with immobilized TCR-specific mAb plus IL-2. Lineage decision invariably occurs toward CD4−8+, regardless of the timing of TCR stimulation after entry into the CD4+8+ compartment or the concentration of TCR-specific mAb used for stimulation. CD4-specific mAb synergizes with suboptimal TCR-specific mAb in inducing T cell maturation, but lineage decision remains exclusively CD4−8+. These results contrast with those obtained in mice, in which Abs to the TCR complex were shown to promote CD4+8− T cell maturation from CD4+8+ thymocytes. Surprisingly, when rat and mouse CD4+8+ thymocytes were stimulated with PMA/ionomycin under identical conditions, the opposite lineage commitment was observed, i.e., mouse thymocytes responded with the generation of CD4+8− and rat thymocytes with the generation of CD4−8+ cells. It thus seems that CD4+8+ thymocytes of the two species respond with opposite lineage decisions to strong activating signals such as given by TCR-specific mAb or PMA/ionomycin. A possible key to this difference lies in the availability of p56lck for coreceptor-supported signaling. We show that in contrast to mouse CD4+8+ thymocytes, which express both a complete and a truncated CD8α-chain (CD8α′) unable to bind p56lck, rat thymocytes only express full-length CD8α molecules. Mice, but not rats, therefore may use CD8α′ as a “dominant negative” coreceptor chain to attenuate the CD8 signal, thereby facilitating MHC class II recognition through the higher amount of p56lck delivered, and rats may use a different mechanism for MHC class distinction during positive selection.
TGF-β1 Induces the Cyclin-Dependent Kinase Inhibitor p27Kip1 mRNA and Protein in Murine B Cells
Authors: Kamesaki Hiroshi , Nishizawa Kimiko , Michaud Ginette Y. , Cossman Jeffrey , Kiyono Tohru 
Published: January 2023

Abstract
TGF-β1 inhibits the cell cycle progression of many types of cells by arresting them in the G1 phase. This cell cycle arrest has been attributed to the regulatory effects of TGF-β1 on both the levels and the activities of the G1 cyclins and their kinase partners. The activities of these kinases are negatively regulated by a number of proteins, such as p15INK4b, p21WAF1/Cip1, and p27Kip1, that physically associate with cyclins, cyclin-dependent kinases (Cdk), or cyclin-Cdk complexes. In epithelial cell lines, TGF-β1 was previously shown to inhibit cell cycle progression through down-regulation of Cdk4 and/or up-regulation of p15INK4b and/or p21WAF1/Cip1. However, TGF-β1 had little or no effect on the p27Kip1 mRNA and protein levels. In this report, we show that, in contrast to observations in epithelial cell lines, TGF-β1 increased the p27Kip1 mRNA and protein levels in the murine B cell lines CH31 and WEHI231. This TGF-β1-mediated induction of p27Kip1 also resulted in an increased association of p27Kip1 with Cdk2 and a decreased Cdk2 kinase activity. In contrast to epithelial cells, however, TGF-β1 had little or no effect on the Cdk4 and p21WAF1/Cip1 protein levels in these B cells. Finally, although several studies suggested a direct role of p53 in TGF-β1-mediated cell cycle arrest in epithelial cells, TGF-β1 inhibited cell cycle progression in CH31 even in the absence of wild-type p53. Taken together, these results suggest that TGF-β1 induces G1 arrest in B cells primarily through a p53-independent up-regulation of p27Kip1 protein.