bluuebunny/crossref_metadata_2025_split huggingface dataset:
Characterization of differential innate and adaptive immunity against Rickettsia conorii in resistant and susceptible mice (52.14)
Authors: Fang Rong , Ismail Nahed , Walker David H. 
Published: January 2023

Abstract
Spotted fever group (SFG) rickettsiae cause severe human diseases in many endemic areas of the world. In order to identify the critical factors in determining host susceptibilities or resistance to SFG rickettsiosis, we characterized cellular immunity against R. conorii in highly susceptible C3H/HeN (C3H) mice, relatively susceptible BALB/c mice and highly resistant C57BL/6 (B6) mice. A dose of rickettsiae lethal to C3H mice is cleared by all wild type (WT) B6 and BALB/c mice in 4 days with survival. Compared to C3H mice, significantly higher expansion of natural killer (NK) cells was detected in WT B6 mice. Similar to the respective WT mice, all RAG−/− and IL-12p40−/− knockout mice on B6 background and SCID on BALB/c background survived, whereas BALB/c SCID mice with deficiency of NK cells died. These findings suggest that NK cells play a major role in the innate immunity, which is IL-12p40- independent in the resistant host. Protection against sublethal rickettsial infection in C3H mice was associated with a CD4+ Th1 cell response, the presence of greater quantities of inducible CD4+CD25+ T regulatory cells and CTL than in B6 mice. These findings suggest that a cell-mediated Th1 immune response is critical for protection against rickettsial infection in the susceptible host and T regulatory cells may contribute to the outcome of rickettsial infection, most likely through balancing T cell mediated protective immunity and immunopathology.
This work was supported by a grant (AI021242) from the National Institute of Allergy and Infectious Diseases.
Neuroinflammatory pathways induced by TLR7 stimulation in the developing brain (52.3)
Authors: Butchi Niranjan Babu , Pourciau Susan , Peterson Karin E 
Published: January 2023

Abstract
Activation of astrocytes and microglia (gliosis) and the production of proinflammatory cytokines and chemokines are often associated with virus infection in the CNS as well as autism and cerebral palsey. Neonates have poor adaptive immune responses to virus infections. Instead, innate immune response may play an important role in protection from virus mediated damage to the brain. Innate immune responses are often initiated by recognition of pathogen associated molecular patterns that stimulate toll like receptors. TLR7 and 8 were identified as eliciting anti viral effects when stimulated by viral single stranded RNA. To examine the potential of TLR7 to induce glial activation and neuroinflammation, we stimulated astrocyte cells (C8-DIA) with TLR7 ligands, Imiquimod and Loxoribine. Imiquimod induced the upregulation of Ifnb1 or Tnf á mRNA at 48 hrs post stimulation in astrocyte cultures. In contrast, Loxoribine did not induce Ifnb1 or Tnf á mRNA in astrocyte cultures but induce these responses in control macrophage cells. This showed the differential activation of astrocyte by different TLR7 ligands. To determine the effect of these TLR7 ligands in vivo, a single inoculum of either Imiquimod or Loxoribine was injected intracerebrally into new born mice. We are currently analyzing effect of TLR7 stimulation on induction of proinflammatory cytokines, chemokines, gliosis and adhesion molecule in the brain.
NTAL Negatively Regulates TREM-1/DAP12 Function (52.6)
Authors: Tessarz Anja S , Weiler Sandra , Zanzinger Kai , Angelisová Pavla , Horejší Václav , Cerwenka Adelheid 
Published: January 2023

Abstract
Engagement of Triggering Receptor Expressed on Myeloid cells (TREM-1) on macrophages and neutrophils leads to TNF-α and IL-8 production and enhances inflammatory responses to microbial products. For signal transduction, TREM-1 couples to the ITAM-containing adapter DNAX Activation Protein of 12 kDa (DAP12). In general, ITAM-mediated signals lead to cell activation, although DAP12 was recently implicated in inhibitory signaling in mouse macrophages and dendritic cells. So far, signals downstream of the TREM-1 and DAP12 complex in myeloid cells are poorly defined. By analyzing receptor-induced tyrosine phosphorylation patterns, we discovered that ligation of TREM-1 leads to tyrosine phosphorylation of the Non-T cell Activation Linker (NTAL/LAB) in a myelo-monocytic cell line and primary human granulocytes. Using RNA interference to decrease expression levels of NTAL, we demonstrate that in NTAL knock-down cell lines phosphorylation of ERK 1/2 is enhanced. In addition, low levels of NTAL are correlated with decreased and delayed mobilization of Ca2+ after TREM-1 triggering. Most importantly, we demonstrate that NTAL acts as a negative regulator of TNF-α and IL-8 production after stimulation via TREM-1. Our results show that activation signals delivered via DAP12 can be counterbalanced by the adaptor NTAL, identifying NTAL as gatekeeper of TREM-1/DAP12-induced signaling in myeloid cells.
Supported by a Marie Curie Excellence Grant (002739) to AC.
Polyanion-induced self-association of complement factor H: possible mechanism of host protection from an innate immune system (53.11)
Authors: Pangburn Michael K. , Rawal Nenoo , Ferreira Viviana P. , Atkinson Mark A.L. 
Published: January 2023

Abstract
Factor H is the primary soluble regulator of activation of the complement alternative pathway. It prevents activation of complement on host cells and tissues upon association with surface polyanions such as sialic acids, heparin and other glycosaminoglycans. We now show that interaction with polyanions causes self-association forming tetramers of the 155,000 dalton glycosylated protein. Monomeric human factor H is composed of twenty homologous CCP domains and in its extended form it exists as a flexible protein approximately 380 to 730 angstroms in length and 35 angstroms in width. Due to its extended shape, it exhibits an apparent size of 330,000 daltons, relative to globular standards, during gel filtration in the absence of polyanions. In the presence of dextran sulfate (5,000 daltons) its apparent Mr was found to be 1,400,000 daltons by gel filtration. Similar effects were seen with heparin. Sedimentation equilibrium analysis by analytical ultracentrifugation indicated a monomer Mr of 163,000 in the absence of polyanions and a tetramer of 607,000 Mr in the presence of less that a two-fold molar excess of dextran sulfate. The results suggest that recognition of polyanionic markers on host cells and tissues by factor H and the resulting inhibition of complement activation may involve formation of dimers and tetramers of factor H.
Support: NIH grant DK-35081, NIH grant HL-073804 and AHA grant 0265178Y.
Proteins involved in prophenoloxidase activating system and their roles in mud crab Scylla serrata (53.12)
Authors: Chen Jiann-Chu , Lin Yong-Chin , Vaseeharan Baskarakingam 
Published: January 2023

Abstract
Several proteins like proPO (prophenoloxidase), peroxinectin, serine proteinase and serine proteinase inhibitors such as pacifastin and a2-macroglobulin are involved in the proPO activating system. Isolation and purification of these proteins and cloning of these proteins have been widely studied in penaeid shrimp, crayfish and lobster. Recently we have cloned proPO, serine proteinase, and a2-macrglobulin from the haemocytes of mud crab Scylla serrata, an important commercial species in Asia and Oceania. The cDNA clone of proPO has a full-length of 2663 bp, with an open reading frame of 2019 bp, a 124-bp 5?untranslated region, and a 520-bp 3?untranslated region containing a poly A signal. It encodes a protein of 673 amino acids with a predicted molecular weight of 77.5 kDa and with an estimated pI of 5.96. The cDNA clone of serine proteinase has an open reading frame of 1131 bp encoding a protein of 376 amino acids. The calculated molecular mass of the serine proteinase is 39.54 kDa with an estimated pI of 5.37. The cDNA clone of a2-macroglobulin has a full-length of of 5491 bp with an open reading frame (ORF) of 4986 bp encoding a protein of 1662 amino acids with 22 residues signal sequence. The calculated molecular mass of the mature protein is 184.2 kDa with an estimated pI of 8.41. Comparison of each protein of this species with that of other arthropod available in the GenBank, and phylogenetic analysis of each protein are discussed.
Upon ligation, CD35 (CR1) interacts with the Cdc42-binding protein Par6 in human neutrophils (53.13)
Authors: Ghiran Ionita Calin , Lawler Matthew Ryan , Nicholson-Weller Anne 
Published: January 2023

Abstract
Inflammation associated with infections is composed of well-choreographed sequences of pro- and anti-inflammatory responses. Among opsonins, the same paradigm is followed. While the signaling pathways mediated by the IgG receptors are well defined in neutrophils (PMN), little is known about the signaling pathway of CR1 (or CD35), the receptor for all nascent complement opsonins.
Our data provide evidence that in PMN, the cytoplasmic domain of CR1, which contains two PDZ motifs interacts with Par6 (partition defective protein) a PDZ domain-containing cytoplasmic protein, initially described in C. elegans and later in virtually all organisms from worms to humans. By virtue of its several protein-protein interacting domains, Par6 is involved in a wide range of cellular processes such as cell polarity, neuronal division and directed cell migration. Using its CRIB-like motif, Par6 binds Cdc42 and Rac1, GTPases involved in generating reactive oxygen species following FcR ligation. Our data show that the PDZ domain of Par6 interacts “in vitro” with the cytoplasmic tail of CR1 as assessed by protein array and BiaCore analyses and “in vivo” as assessed by co-immunoprecipitation of human PMN. We have demonstrated Par6 expression in PMN using flow cytometry, microscopy and western blot analyses. We hypothesize that in human PMN, CR1 attenuates pro-inflammatory response by binding Par6 and thereby preventing formation of the functional pro-inflammatory complex (Par6/Cdc42/Rac1) essential to Fc receptors signaling.
Complement C2 bypass mechanism involving the C3-convertase C4bBb (53.16)
Authors: Inal Jameel Malhador , Laich Andreas , Miot Sylvie 
Published: January 2023

Abstract
The majority of patients with a homozygous complement C2 (C2) deficiency show no or only minor disease, at most one third showing mild symptoms of systemic lupus erythematosus. This suggests that classical pathway activation is not solely dependent on C2. We show that factor B (FB) the alternative pathway homologue of C2 can substitute for C2. In ELISA, FB was found to complex with immobilised C4b. This was confirmed by surface plasmon resonance, giving an estimated binding constant of 2.0 x10−5 M. Furthermore Factor D was able to cleave factor B in the presence of C4b. The hybrid C3 convertase formed, C4bBb, also cleaved 125I-C3 at a low level, further supporting previous evidence of a C2-bypass mechanism.
Unique tissue distribution and molecular heterogeneity of human Fc receptor for IgA and IgM (Fcα/μR) (53.17)
Authors: Nishizaki Naoto , Grizzle William E. , Stockard Cecil R. , Kikuno Kaoru , Kubagawa Hiromi 
Published: January 2023

Abstract
Fcα/μR consists of an extracellular region with an N-terminal single Ig-like domain and a membrane proximal stalk region, a transmembrane (TM) segment and a cytoplasmic tail. Fcα/μR binds the polymeric IgM and IgA and is expressed by follicular dendritic cells in germinal centers, small intestinal Paneth cells, renal tubular epithelial cells and serous small epithelial cells of salivary glands in humans. Analyses of its transcripts and genomic DNA revealed the existence of an additional translation start site upstream of the previously isolated Fcα/μR cDNA and a splice variant in kidney tissues. The latter was generated from the direct splicing of exon 5 (Ig-like domain) to exon 7 (TM) and resulted in a reading frameshift in exon 7, generating a novel 48-aa hydrophilic C-terminal tail. To determine the roles of the upstream start site and the alternative splice variant, those cDNA were subcloned into an expression vector prior to establishment of the mouse cell lines stably expressing human Fcα/μR transgene. Transductants with the full-length Fcα/μR cDNA irrespective of the start sites expressed Fcα/μR on their cell surface, whereas those with the Fcα/μR splice variant expressed Fcα/μR associated with intracellular, not plasma, membranes. Protein blot analysis of these cell lysates revealed that the Fcα/μR proteins correspond to their predicted molecular masses.
(Supported by NIH/NIAID AI052243)
Cell surface complement regulatory functions of factor H are essential for the survival of normal and paroxysmal nocturnal hemoglobinuric (PNH) red blood cells (53.2)
Authors: Ferreira Viviana P. , Pangburn Michael K. 
Published: January 2023

Abstract
The complement system uses a complex set of cell-bound and plasma regulators to protect host cells from complement-mediated cytolysis. Although PNH red blood cells (RBCs) are partially (type II) or completely (type III) deficient in GPI-linked complement regulatory molecules CD59 and CD55, they are not rapidly lysed by complement. For instance, the in vivo lifespan of PNH III RBCs is 6–60 days, and is close to that of normal cells for PNH II RBCs. The plasma regulator factor H (fH) plays a key role in complement homeostasis. Here we show that a recombinant protein consisting of its two C-terminal domains (rH19-20) blocks its cell surface complement regulatory functions without affecting fluid phase control of soluble C3b. Also, addition of rH19-20 to normal human serum leads to moderate complement-mediated lysis of normal human RBCs, which possess membrane-bound complement regulators, and to aggressive lysis of PNH II and III cells. In agreement with this, the inhibition of CD59 or CD55 on normal RBCs results in their aggressive lysis only when combined with the loss of fH cell surface control. Taken together, the results highlight the importance of the cell surface protective functions of fH compared to other complement regulatory proteins and indicate that fH is essential for the 6–60 day survival of PNH RBCs, with possible implications in diagnosis and treatment.
Research support NIH DK35081.
Properdin: Cell Death’s Little Helper? (53.3)
Authors: Kemper Claudia , Mitchell Lynne M , Hourcade Dennis E 
Published: January 2023

Abstract
Apoptosis is a mechanism for the safe elimination of undesirable cells without evoking an immune response. C3b/C4b-opsonization of apoptotic cells through classical and lectin complement pathway activation is a major mechanism to mark these cells for clearance by scavenger cells. Recently we observed that the serum protein properdin bound to a biosensor surface leads to direct alternative pathway activation. Here we determine whether properdin can also direct complement activation to physiological targets i.e. human apoptotic T cells.
We found that:
Properdin (purified and in serum) binds apoptotic and necrotic CD4+ T cells, but neither non-activated nor viable activated T cells;Properdin bound to apoptotic cells initiates de novo complement activation and phagocytosis by dendritic cells/macrophages;Surprisingly, properdin also enhanced phagocytosis of apoptotic cells independently of complement activation.
We propose that properdin directly recognizes apoptotic T cells, promoting their targeted uptake by phagocytes. This mechanism represents a novel pathway for the identification and removal of undesired cells.
Funded by NIH R01 AI05143 (to DH).
The Neonate Fc Receptor (FcRn) For IgG Is Important For The Development of Rotavirus-Specific IgG Responses And Clearance of Rotavirus From The Intestines Of Mice (53.5)
Authors: Marcelin Glendie , Conner Margaret E 
Published: January 2023

Abstract
Rotavirus infection and virus-like particle vaccines induce intestinal rotavirus-specific IgG in mice that appears to play a role in protection. The mechanism by which rotavirus-specific IgG reaches the intestinal lumen is unknown. The neonatal Fc receptor for IgG (FcRn) is the only known transporter of IgG in the intestines in neonatal and adult mice. Additionally, FcRn is implicated in antigen presentation in the intestines of adult mice. We tested whether FcRn is important in protecting the intestine against rotavirus infection and in transport of rotavirus-specific IgG into the intestinal lumen. Naïve FcRn deficient (FcRn−/−) and wild type BALB/c controls were orally inoculated with 103ID50 ECWT rotavirus. Fecal samples were collected 0–12 days post inoculation (dpi) and tested for rotavirus antigen and rotavirus-specific IgG by ELISA. Virus clearance from the intestine was significantly delayed by 3 days in FcRn−/− compared to BALB/c mice. Rotavirus-specific intestinal IgG titers were also significantly lower in FcRn−/− versus BALB/c mice. These data indicate that FcRn plays a role in clearance of a primary rotavirus infection from the intestine and intestinal transport of rotavirus-specific IgG. Studies are underway to elucidate the mechanism(s) by which FcRn contributes to clearance of intestinal rotavirus infection.
VA Merit Review Grant, NIH RO1 AI24998
Presence of Id2− and RORγt-independent lymphoid tissue organogenesis (81.2)
Authors: Nagatake Takahiro , Fukuyama Satoshi , Kim Dong-Young , Takamura Kaoru , Kiyono Hiroshi 
Published: January 2023

Abstract
Id2 and RORγt have been shown to be the essential transcriptional regulators for the differentiation of CD3−CD4+CD45+ lymphoid tissue inducer cells (LTi). LTi migrate to the site of tissue genesis and provide the signal mediated by membrane-bound lymphotoxin (LT)α1β2, which results in the subsequent production of chemokines and adhesion molecules including CXCL13 and VCAM-1 by LTβR+ stromal cells. Organogenesis of lymphoid tissues such as Peyer’s patches are thus defective in Id2−/−, RORγt−/− and LTα−/− mice. Tear duct-associated lymphoid tissue (TALT) has been identified in human. However, the molecular and cellular requirements of TALT-genesis are totally unknown. Here we provide the first definitive evidence for the presence of Id2− and RORγt-independent tissue genesis program. We thus located the murine TALT in nasolacrimal duct and revealed that TALT-genesis did not require Id2, RORγt and LTα. TALT-genesis was initiated at postnatal days and developed in germ free and MyD88−/− mice. These results demonstrated that TALT has indeed developed using the unique pathway compared with other secondary lymphoid organs.
LIM Domain Binding Protein 1 (Ldb1) is Required for the Maintenance of Hematopoietic Stem Cells (81.4)
Authors: Li LiQi , Lee Jan , Cohen Tsadok , Gorivodsky Marat , Hayes Sandra M. , Zhao Yangu , El-Khoury Dalal , Grinberg Alexander , Westphal Heiner , Love Paul E. 
Published: January 2023

Abstract
Ldb1 is a ubiquitous nuclear protein that functions by interacting with and/or recruiting specific partners (including LMO2, SCL and GATA-1) to form multi-molecular DNA-binding transcription complexes. In the hematopoietic lineage, expression of Ldb1 is highest in lineage−Sca1+c-kit+ (LSK) multipotent progenitors. Ldb1 gradually decreases as cells mature within lymphoid or granulocyte/macrophage lineages, but remains high in erythroid lineage cells. We investigated the role of Ldb1 in hematopoiesis by conditional deletion of Ldb1 using a cre transgene driven by the Tie2 promotor; or by following the fate of Ldb1-null embryonic stem (ES) cells in mouse blastocyst chimeras. The number of Ter119+ (erythroid lineage) cells was decreased dramatically in Tie2Cre+Ldb1flox/flox mice, revealing a critical role for Ldb1 in erythropoiesis. Ldb1-null ES cells were capable of generating LSKs in the fetal liver and these cells could give rise to both myeloid and lymophoid lineage cells; however, the number of Ldb1−/− LSKs was markedly decreased at later stages of development. Following adoptive transfer, Ldb1-null fetal liver LSKs were rapidly lost indicating a failure of self-renewal or survival. Loss of Ldb1 was associated with an increase in multipotent progenitor (MPP) cells and a decrease in hematopoietic stem cells (HSCs), suggesting that Ldb1 participates in stem cell maintenance. These data provide the first evidence that LIM domain binding proteins function in hematopoiesis, and identify Ldb1 as a critical factor in regulating HSC maintenance/self-renewal.
Liver plasmacytoid dendritic cells stimulate NK1.1+ cells (82.12)
Authors: Nguyen Hoang Minh Lawrence , Kingham T. Peter , Plitas George , Burt Bryan M. , Chaudhry Umer I , DeMatteo Ronald P. 
Published: January 2023

Abstract
Introduction: Plasmacytoid dendritic cells (pDC) play a central role in innate immunity. While much is known about spleen pDC, liver pDC has only been recently identified and their function remains largely unknown. We sought to determine the ability of liver pDC to stimulate NK1.1+ cells in vitro in comparison to spleen pDC.
Methods: Liver and spleen pDC (CD11c+B220+NK1.1−CD19−CD11b−) from C57BL/6 mice were expanded in vivo with an adenovirus encoding murine Flt3L cDNA and isolated by fluorescence activated cell sorting. These cells were co-cultured with spleen NK1.1+ cells in the presence of CpG with or without a transwell insert. After 24 hours, supernatant IFN-γ level was determined by cytometric bead array. Additionally, α-GalCer –loaded liver and spleen pDC were stimulated with CpG and cultured with spleen NK1.1+ cells in the presence of CpG. IFN-γ production was measured after 24 hours.
Results: Flt3L-expanded liver pDC stimulated with CpG induced significantly higher CD69 expression on NK cells when compared to spleen pDC. CD69 expression by both groups was reduced by the presence of a transwell insert. Both liver and spleen pDC loaded with α-GalCer and stimulated with CpG induced large amounts of IFN-γ secretion by NK cells.
Conclusion: Upon expansion and stimulation, liver pDC are able to stimulate NK cells in vitro. This is partially mediated through cell-cell contact.
This work was supported by grant DK068346
NK cell phenotypes in Foxk1 deficient mice (82.13)
Authors: Moody Leslie A , Alexander Matthew S , Jiang Nan , Garry Daniel J , Bennett Michael 
Published: January 2023

Abstract
Foxk1 is a member of the forkhead/winged-helix transcription factor family. Foxk1−/− mice have a gross deficit of natural killer (NK) cells, roughly three-fold, in the spleen, peripheral blood and bone marrow. Both mature and immature NK cells are lacking in the affected tissues. NK cells are the only major lymphocyte compartment affected. Bone marrow chimera experiments between Foxk1−/− and B6 (control) mice have shown that the defect is NK cell intrinsic. The remaining NK cells in Foxk1−/− are functionally defective directly ex vivo as determined by YAC-1 killing. However, following in vitro culture with either IL-2 or IL-15, the Foxk1−/− NK cells regain lytic function. To further analyze the cytotoxic defect of Foxk1−/− NK cells, we have examined the expression of components of the lytic pathway. Foxk1−/− NK cells express lower amounts of Perforin, but increased amounts of FasL, compared to B6 mice. These levels of cytotoxic effector molecules still do not provide us with an answer as to why Foxk1−/− NK cells have a defect in lytic function. To examine the NK cell number deficit in Foxk1−/− mice we have used flow cytometry to assess the various developmental stages of NK cells in Foxk1−/− and B6 mice and have found that Foxk1−/− mice had altered cell surface marker expression at the earliest progenitor stage. Gene expression profiles of early precursors from B6 and Foxk1−/− mice are being examined by microarray analysis.