bluuebunny/crossref_metadata_2025_split huggingface dataset:
Loss of CD28 expression in human T cells: possible causes and downstream effects (33.24)
Authors: Parish Stanley T , Wu Jennifer , Sekhon Rekha , Effros Rita B 
Published: January 2023

Abstract
High proportions of CD8+CD28- T cells are present during HIV infection and aging. These cells, which have features of replicative senescence, are associated with decreased vaccine responses, early mortality, and progression to AIDS. To identify the underlying mechanisms for CD28 downregulation, we first analyzed caspase-3, which inhibits the CD28 promoter. Both CD28- T cells tested immediately ex vivo and cells that reached replicative senescence in vitro have significantly greater caspase-3 levels than their CD28+ counterparts. This increase is reversed in cultures in which CD28 expression is maintained by inhibiting TNFα. We next addressed the possible role of adenosine, which is released from metabolically active cells, and which, when added to long-term cultures, downregulates CD28. We showed that adenosine deaminase (ADA), which converts adenosine to inosine, is more highly expressed on CD28+ vs. CD28- T cells. These data suggest multiple regulatory pathways for CD28 gene suppression. Irrespective of the precise mechanism, once cells lose CD28 expression, they show decreased transcription of numerous glycolysis pathway enzymes, consistent observations on ex vivo T cells from older persons. Our data, which help elucidate the complexity of CD28 downregulation and its downstream consequences, may lead to therapeutic strategies to prevent accumulation of senescent T cells in vivo. (NIH AG023720).
Heat shock factor 1 is activated in lymphoid cells as a consequence of antigen recognition and is critical for cell cycle progression during an immune response (33.25)
Authors: Gandhapudi Siva K , Murapa Patience , Sarge Kevin D , Woodward Jerold G 
Published: January 2023

Abstract
Heat shock factor 1 (HSF1) is the dominant transcription factor controlling the cellular response to a variety of cellular stress signals. We now demonstrate that HSF1 becomes activated to the DNA binding form and trans-activates a large number of genes in lymphoid cells strictly as a consequence of receptor activation in the apparent absence of stress. Furthermore, this activation stabilizes cell cycle progression, becoming increasingly critical in the face of stress. EMSA assays revealed the DNA binding form of HSF1 in activated lymphocytes, but not in naïve cells at 37oC. Microarray analysis comparing WT and KO gene expression in T cells activated at 37oC revealed a diverse set of 307 genes significantly regulated by HSF1 in non-stressed T cells. HSF1-/- T or B cells proliferated normally under benign conditions of anti-CD3 or LPS stimulation in vitro. However, proliferation was severely compromised under conditions mimicking a robust immune response (SEB induced T cell activation) or stress (39oC). Western blotting revealed that the block in proliferation was associated with an inability to up-regulate cyclin A resulting in a block in cell cycle progression. Finally, hematopoetic stem cell proliferation from HSF1-/- mice, but not WT mice was also attenuated at elevated temperatures, indicating that HSF1 is a major regulator of hematopoetic cell cycle progression under stress.
T cells can be activated by physical forces acting on T cell receptor complex (33.4)
Authors: LI YA-CHEN , Chen Bing-Mae , Wu Pei-Chun , Roffler Steve R. 
Published: January 2023

Abstract
T cell receptor (TCR) are recognized by major histocompatibility complex (MHC) which binds antigenic peptides to activate T cell for prevention of infections and cancers. The T cell activation cascades that result in T cell proliferation, differentiation and cytokine secretions are well studied in the past years. However, the mechanism of T cell receptor triggering is still unclear so far. In this study, we expressed single- chain antibodies (scFv) or single- chain MHC (scMHC) molecules on artificial antigen presenting cell (APCs) and micromanipulating single T cells that bind to the engineered APCs. We found the mechanical force can initiate T cell activation via TCR signaling. In addition, increasing the dimensions of intercellular adhesion molecules-1 (ICAM-1) on the APCs can promote T cell activation by elongating TCR ligands. Our data indicated that ICAM-1 and leukocyte function-associated antigen-1 (LFA-1) interaction may play an important role to regulate the force in TCR triggering.
Monte Carlo model elucidates mechanisms of B cell affinity discrimination and its modulation by B cell immune synapse formation (34.1)
Authors: Raychaudhuri Subhadip , Tsourkas Philippos 
Published: January 2023

Abstract
B cells are known to use their signaling mechanism to recognize antigens over a wide range of affinities (10 6 -
10 10 M -1) and generate a graded response that depends on the affinity of antigen binding, a phenomenon known as affinity discrimination. However, the molecular mechanism behind such affinity discrimination is not clear. We have developed a computational model of B cell signaling that reveals that a minimum threshold time of BCR-antigen binding is needed for such affinity discrimination to occur. For a given antigenic affinity, our numerical experiments give rise to stochastically varying levels of activated signaling molecules, such as phosphorylated BCR ITAMs and Syk molecules, as is the case in single cell experiments. Recent experiments have revealed that B cell signaling is coupled with the immunological synapse pattern - an ordered protein segregation structure consisting of BCR/Antigen and LFA-1/ICAM-1 molecules that forms at the cell-cell contact area. We used our Monte Carlo computer model to show that synapse formation modulates the affinity discrimination in B cells.
PGE2 Upregulates Activation-Induced Cytosine Deaminase (AID) in Human B Lymphoblasts (34.12)
Authors: Mongini Patricia K. A. , Chiorazzi Nicholas , Haque Shabirul , Trott Joshua 
Published: January 2023

Abstract
AID is expressed in mature B cells during activation and in some non-lymphoid tissues during inflammation and malignancy. Elevated COX-2 & PGE2 characterize all the above and may be involved. We here confirm that PGE2 enhances AID in activated human B2 cells (J Immunol. 178:35.4, 2007 abstract) and explore the mechanism. AID was assessed, by immunoblotting and two-color flow cytometry of CFSE-labeled cells, following activation by anti-IgM:anti-CD21:dex + IL-4 + BAFF w/wo PGE2 or agonists/antagonists of PGE2 receptors (EP1, EP2, EP3, and EP4). PGE2 added at physiological doses augmented AID. EP2 was involved on the basis of (a) AID-augmenting effects of an EP2-specific agonist and (b) concordant upregulation of AID and EP2 on replicating blasts. Furthermore, PGE2-mediated elevation of AID was thwarted by inhibitors of PKA, downstream of EP2. To examine whether autocrine PGE2 synthesis contributes to AID, replicating cells were assessed for mPGE2-1 - an enzyme that converts COX-2-generated PGH2 to PGE2. Elevated mPGE2-1 in progeny and COX-2 inhibitor-reduced AID both suggest that autocrine PGE2 promotes AID. Additionally, functional AID (on the basis of IgG+ progeny) was elevated and reduced by exogenous PGE2 and COX-2 inhibitors, respectively. Thus PGE2, elaborated by classic inflammatory cells or generated during activation, augments AID expression/function in EP2-expressing human B lymphoblasts. NIH R01 AI52189; M01 General Clinical Research Center grant RR018535; and Karches Foundation
CD19-dependent signaling pathways activated by IgM ligation, CD19 ligation or simultaneous IgM and CD19 ligation demonstrate differential requirements for Lyn and Syk kinase activities (34.17)
Authors: Kountikov Evgueni I , Poe Jonathan C , Tedder Thomas F 
Published: January 2023

Abstract
CD19 is a transmembrane protein with a cytoplasmic domain containing nine tyrosines that mediate associations with multiple signaling molecules. In response to cell surface IgM ligation, CD19 is phosphorylated by Lyn kinase and establishes a Src-family kinase amplification loop using tyrosines Y482 and Y513. These residues are also required for induction of Ca2+ response via binding of PI 3-kinase (PI3K). In this study, CD19 proteins with amino acid changes that prevent either PI3K or Lyn binding, or both, were stably expressed in CD19 deficient B cells and used to examine the role of CD19 in Ca2+ responses. Optimal IgM-induced Ca2+ responses required both Lyn and PI3K binding to phosphorylated CD19. However, CD19 ligation-induced Ca2+ responses did not require Src-family kinase amplification or PI3K binding to phosphorylated CD19. Instead, CD19 ligation induced a pool of activated Vav via a Syk kinase-dependent pathway that did not induce BLNK tyrosine phosphorylation. By contrast, IgM and CD19 co-ligation synergistically enhanced Ca2+ responses through a Syk-dependent pathway that correlated with enhanced BLNK and Vav phosphorylation. Thus, IgM or CD19 engagement alone, or co-ligation of these receptors, induced qualitatively and quantitatively unique physiological outcomes. This research was supported by NIH grant CA096547.
Reduced response to influenza vaccine associates with reduced AID in aged human B lymphocytes (34.5)
Authors: Blomberg Bonnie B. , Romero Maria , Landin Ana Marie , Diaz Alain , Riley Richard L. , Frasca Daniela 
Published: January 2023

Abstract
Elderly humans have compromised humoral and cellular immune responses, which lead to reduced protection to infectious agents and to vaccines. Currently, available vaccines suboptimally protect the elderly population. The capacity to class switch the Immunoglobulin (Ig) H chain is critical to the effectiveness of humoral immune responses in mice and humans. We have previously shown that elderly humans have fewer percentages of CD19+ total B cells, switch memory B cells, and increased percentages of naïve B cells. Activated CD19+ B cells also have less E47, AID and Igγ1 circle transcripts (CTs) with age. AID is critical for class switch recombination (CSR) and somatic hypermutation (SHM), both necessary for optimal function of Ig. More recently we have found the antibody hemagglutination inhibition (HI) assay response to the influenza vaccine is decreased in elderly (as others have previously shown) and this associates with the decrease in AID in the activated B cells from the same subjects. The mechanism that we have previously shown in mice and humans to regulate CSR (E47, AID, IgG CTs) in aging can now be used to evaluate the response to the influenza vaccine.
This work is supported by NIH AG-23717 and AG28586 (BBB) and AG025256 and AI064591 (RLR)
Computational studies of B cell receptor diffusion elucidate mechanisms of B cell immune synapse formation (34.8)
Authors: Raychaudhuri Subhadip , Tsourkas Philippos 
Published: January 2023

Abstract
B cells are shown to form immunological synapse, an ordered protein segregation structure consisting of BCR/Antigen and LFA-1/ICAM-1 molecules, at the cell-cell contact area between a B cell and an antigen-presenting cell. The formation mechanisms of the B cell immune synapse seem to be complex and a combination of different mechanisms are possibly in effect, including a directed transport of receptors to the central cell-cell contact area. We have studied receptor diffusion at the single molecule level during B cell synapse formation using a combination of theoretical and computational models. Results from detailed computer simulations show slow sub-diffusive transport of receptors during the course of synapse formation. Such a sub-diffusive transport becomes slower with increasing affinity of BCR-antigen bonds and thus directed receptor transport for high affinity antigens is needed for synapses to form in biologically relevant time-scales. Recent single molecule tracking experiments also revealed slow diffusion of receptors in regions of antigen binding. A simple theoretical model of receptor diffusion and clustering is proposed that clearly elucidates that sub-diffusive nature of receptor trafficking can arise due to receptor-ligand binding at a curved cell-cell contact zone.
Immunoglobulin A secretion is enhanced in allergic mice lacking the VPAC-2 receptor (39.15)
Authors: Samarasinghe Amali E. , Hoselton Scott A. 
Published: January 2023

Abstract
Chronic asthma is a TH2 mediated disease characterized by eosinophilic inflammation and elevated immunoglobulin (Ig)E. Acting through its G-protein coupled receptor VPAC-2, vasoactive intestinal peptide (VIP) supports a TH2 phenotype regulating lymphocytes and macrophages. IgA, produced at the lung mucosa, is important in host defense. VIP has been reported to enhance the number of IgA secreting precursors, and increase IgA while decreasing IgG. Since VPAC-2 transgenic mice have elevated antibodies and eosinophils, we hypothesized that VPAC-2 null mice will have decreased antibodies and eosinophils in an allergy model. C57BL/6 wild type (WT) and VPAC-2 null (KO) mice were sensitized with Aspergillus fumigatus antigen and challenged twice two weeks apart with live conidia. Cells in the bronchoalveolar lavage (BAL) were differentially stained and counted at days 3, 7, 14, 28 and 42 following allergen challenge. IgA in the BAL fluid (BALF), and IgE, IgG2a and IgA in sera were analyzed in both groups. Local IgA producing cells were identified with immunohistochemistry. Eosinophil recruitment and egress in the KO mice were delayed (peak at day 7) in comparison to the WT (peak at day 3). Decreased serum IgA and IgG2a and increased IgE was observed in the WT, while all three antibodies were elevated in the sera of KO mice. More IgA was available in the BALF of KO mice with the peak in IgA coinciding with peak eosinophils in the lumen at day 7. IgA producing cells were located around the blood vessels and airways in both groups. VPAC-2 null mice have elevated basal antibody levels compared to the WT controls which may indicate that VIP suppresses antibody production by acting through VPAC-2. Elevated IgA in the BALF may indicate enhanced mucosal defense in KO mice although the lack of VPAC-2 does not protect these mice from developing allergic asthma in our model. (2P20RR015566)
Vaginal Langerhans cells resist genomic integration of HIV-1 but transmit endocytosed virions to susceptible target cells (39.27)
Authors: Robinson Barry R , Ballweber Lamar , Kreger Allison , Lentz Gretchen M , Fialkow Michael F , McElrath M. Juliana , Hladik Florian 
Published: January 2023

Abstract
B: Vaginal Langerhans cells (LCs) efficiently endocytose HIV-1 (Immunity 2007, 26:257-70), but the ability of LCs to become productively infected or to transmit HIV to mucosal CD4+ T cells is unclear.
M: Epithelial sheets isolated from healthy vaginal mucosa were challenged with HIV-1. After 3 days, isolated cells were sorted by FACS into single LCs (&gt;99% purity) and T cell (TC)-LC conjugates. Integrated HIV-1 was tested in DNA isolated from these cell populations using real-time PCR. LCs and LC-TC conjugates from HIV-challenged tissues were also co-cultured with uninfected T cells and transmission of HIV was evaluated by HIV-1 Gag p24 content in the co-culture supernatants.
R: We detected integrated HIV-1 DNA in 100% (4/4 donors) of the LC-TC conjugates while HIV-1 genomic integration could not be detected in single LCs (0/4 donors). Nevertheless, single LCs transmitted HIV-1 to T cells, which were productively infected (2/3 donors). LC-TC conjugates transmitted HIV-1 to T cells in 3/3 donors.
C: Vaginal LCs resist genomic integration of HIV-1 and are not susceptible to productive infection. However, vaginal LCs are capable of transmitting stored virions to T cells. Thus, in contrast to reports on HIV endocytosis in skin-derived LCs, HIV-1 endocytosis into vaginal LCs is not a dead end for the virus. This infection pathway needs to be considered when designing preventive strategies. Supported by R01 NIH-HD-51455
CCR5 is not required for mucosal protection against Trypanosoma cruzi (39.28)
Authors: Sullivan Nicole L , Eickhoff Christopher S. , Giddings Olivia K , Hoft Daniel F , Lane Thomas E 
Published: January 2023

Abstract
Trypanosoma cruzi is an intracellular obligate parasite and the causative agent of Chagas disease. Previous work has shown that the chemokine receptor CCR5 plays a role in systemic responses against T. cruzi. We evaluated whether CCR5 plays a critical role in mucosal protection against natural oral and conjunctival challenges. Memory-immune CCR5-/- and wild-type C57BL/6 mice were generated by repeated infectious challenges with sublethal doses of insect-derived metacyclic trypomastigotes. Similar IgA, IgG and IFN-γ responses were detected in the spleen in both memory-immune and primary infected wild-type and CCR5-/- mice. More importantly, protection was evaluated in memory-immune mice via real-time PCR and limiting dilution assay for parasite outgrowth. CCR5-/- memory-immune mice developed equivalent levels of protection against both oral and conjunctival mucosal challenges. Preliminary studies from the stomachs of CCR5-/- memory-immune mice showed an increase in the transcript levels of CCL5 as compared to memory-immune wild-type mice. Overall, it appears that CCR5 does not play a critical role in the control of parasite replication and immune responses at sites of initial mucosal infection with T. cruzi. However, CCL5 signaling through CCR1 and/or CCR3 may compensate for the absence of CCR5.
Morphine impairs intestinal immunity and barrier function leading to coagulase-negative staphylococcal bacteraemia (39.30)
Authors: Wang Jinghua , Ma Jing , Barke Roderick A. , Charboneau Richard , Roy Sabita 
Published: January 2023

Abstract
Opiate abuse increases susceptibility to bacterial infection. However, if the intestine can be a potential source of bacterial infections in opiate abusers is not fully elucidated. Using an opiate abuse model, where mice were chronically treated with morphine or placebo pellet, we found that morphine treatment induced bacterial translocation and led to bacteraemia. After morphine exposure, group D Entercocci and coagulase negative Staphylococci were detected in the mesenteric lymph nodes and lungs. Morphine treatment enhanced bacterial growth in the intestine, and that such increased in bacteria was in direct proportion to coagulase-negative staphylococcal bacteraemia. Furthermore, our preliminary findings showed that morphine treatment modulated intestinal intraepithelial gammadelta T cells and impaired intestinal permeability. Moreover, morphine treatment induced dysfunction in intestinal intraepithelial gammadelta T cells was associated with the absence of phosphorylation of occludin and lack of claudin-3 and zona occludens-1 (ZO-1) proteins in tight junction complexes. Our studies suggest that bacterial translocation and bacteraemia occurs in opiate abusers, either on account of a breach of the mucosal barrier, impaired host immune defense, and/or bacterial overgrowth creating an ecologic imbalance in the indigenous intestinal microflora. Supported by R01 DA12104, P50 DA11806, and R03 DA023353.
Role of small intestinal intraepithelial CD11c+ CD8+ T cells in mucosal immunoregulation (39.36)
Authors: Fujiwara Daisuke , Wei Bo , Braun Jonathan 
Published: January 2023

Abstract
The chronic intestinal inflammation tends to occur in the large intestine (LI) rather than in the small intestine (SI) partly due to the relative abundant microbial colonization in LI. However, intestinal intraepithelial T lymphocytes (IEL) in the large intestine are also distinguished from these in the small intestine. In this study, we investigated the possibility that the phenotypic difference of immune populations in two immune compartments might represent their differed immunoregulatory functions for regional control of mucosal inflammation. We observed that in total IELs population, about 36-40% cells in SI and 12-15% cells in LI are CD11c+ and CD3+ double positive cells. The majority of these CD11c+ CD3+T cells were CD8 positive expressing either TCRαβ or γδ. Their T cell lineage was defined by TCR expression and generation of IEL CD11c+ T cells after transfer of CD45.1 splenic T cell into RAG2-/- mice. Compared with CD11c- CD3+ T cells, CD11c+ CD3+ T cells produced significantly lower levels of pro-inflammatory cytokines including TNF-α?and IFN-γ. In mouse model of Gαi2 KO T cells induced colitis, 2.5×105 of SI CD11c+ CD3+ T cells suppressed pro-inflammatory cytokine-producing CD4 T cells at the mucosal sites and protected mice from colitis development. In contrast, LI CD11c+ CD3+ T cells or SI CD11c- CD3+ T cells were ineffective in colitis protection. Taken together, these findings indicate that SI CD11c+ CD8+ T cells might be a functional T cell population that plays an immunoregulatory role in control of pro-inflammatory CD4+ T cells and maintenance of mucosal homeostasis in the intestine.
Antibody-mediated neutralization of RANKL prevents differentiation of M cells in the follicle-associated epithelium of Peyer’s patches (39.4)
Authors: Knoop Kathryn A. , Kumar Nachiket , Butler Betsy R. , Sakthivel Senthil , Taylor Rebekah T. , Nochi Tomonori , Akiba Hisaya , Yagita Hideo , Kiyono Hiroshi , Williams Ifor R. 
Published: January 2023

Abstract
Mucosal surfaces are bombarded with commensal bacteria and foreign antigens. Intestinal Peyer's patches (PP) are inductive sites where secretory IgA production and T cell tolerance are initiated. The follicle-associated epithelium (FAE) over PP includes M cells that transcytose particulate antigens. We have shown that RANKL, a TNF-related cytokine expressed by PP stromal cells, is required for M cell development. UEA-I+ M cells were reduced by &gt;98% in RANKL-/- mice, a defect corrected by s.c. injection of RANKL. We investigated whether acute depletion of RANKL by neutralizing monoclonal antibody (mAb) in BALB/c mice also led to M cell loss. Loss of 70% of UEA-I+ M cells was detected 4 days after every other day injections of 250 μg of rat anti-mouse RANKL mAb (IK22-5). Further loss of M cells occurred after longer treatment, with loss of 92% of M cells after 8 days. Anti-RANKL treatment also led to functional loss of M cell antigen sampling as measured by uptake of 200 nm diameter fluorescent beads. We conclude that continuous RANKL expression on PP stromal cells is essential for the normal differentiation of M cells from epithelial stem cells in crypts adjacent to PP domes.
Phospholipase A2 alters membrane lipid composition during ischemia/reperfusion (39.55)
Authors: Sparkes Byron Lloyd , Woods Keith , Roth Mary , Welti Ruth , Fleming Sherry D 
Published: January 2023

Abstract
Ischemia/reperfusion (IR) injury results in significant tissue damage. Naturally occurring anti-phospholipid antibodies (αPL Ab) induce intestinal prostaglandin E2 (PGE2) and damage when administered to IR resistant Rag-1-/- mice, suggesting involvement of a lipid antigen. Phospholipase A2 (PLA2) hydrolyzes phospholipids releasing lysophospholipid and arachadonic acid, a precursor to PGE2 production. We hypothesized that IR induced PLA2 expression, results in a lipid antigen recognized by αPL Ab. At multiple time points after Sham or IR treatment, lipids extracted from mouse intestinal sections were analyzed by mass spectrometry to determine concentrations of lipid species. Western blot analysis of additional intestinal samples detected specific PLA2 isoforms. Preliminary data indicate that lipid composition is conserved between wildtype and Rag-1-/- mice. However, within 15 min of reperfusion, IR induces significantly more lysophosphatidylcholine and lysophosphatidylethanolamine than Sham treatment. These results correlated with increased PLA2 expression. These data suggest that activation of PLA2 may create a phospholipid neoantigen which is recognized by αPL Ab and lead to tissue damage.