bluuebunny/crossref_metadata_2025_split huggingface dataset:
Expression and Function of P-selectin and its ligand PSGL1 on hematopoietic progenitors (36.4)
Authors: Sultana Dil , Zlotoff Daniel A , Bhandoola Avinash 
Published: January 2023

Abstract
T cells develop in the thymus from bone marrow-derived hematopoietic progenitors that settle the thymus via the blood. The molecular basis for progenitor entry into the thymus is poorly understood, but p-selectin and P-selectin glycoprotein ligand 1 (PSGL1) are suggested to be involved. We investigated the expression of functional PSGL1 able to bind p-selectin. Our preliminary results suggest that functional PSGL1 is expressed at lower levels on primitive hematopoietic stem cells and downstream multipotential progenitors, but at higher levels on downstream early lymphoid progenitors in the bone marrow. These data indicate that P selectin binding is developmentally regulated. Using competitive thymus reconstitution assays we confirmed that PSGL1 is a functionally important component of the thymic homing process. Our current experiments are focused on understanding the mechanism by which PSGL1 is selectively upregulated on thymus homing progenitors.
Smoking cessation reverses cigarette smoke-induced impairment of B cell development and skewed CD4:CD8 T cell ratios in mice (36.43)
Authors: Swanson Patrick , Fusby Jenny , Kassmeier Michele , Palmer Victoria , Perry Greg , Anderson Dirk , Hackfort Bryan , Alvarez Gwen , Akhter Mohammed , Cullen Diane 
Published: January 2023

Abstract
Cigarette smoking is a risk factor for developing osteoporosis, and previous studies suggest lymphocytes are required for normal bone homeostasis and peak bone mass. We hypothesized that lymphocyte development is adversely affected by smoke exposure. If so, this outcome would provide a mechanism to partly explain how cigarette smoking promotes osteoporosis. To test this possibility, we investigated how the duration and cessation of cigarette smoke exposure affected the development, distribution, and function of lymphocytes normal mice. Consistent with the hypothesis, 3-12 weeks of smoke exposure significantly diminished bone marrow B220+CD43- B cell subsets, but, interestingly, did not significantly affect earlier progenitor B220+CD43+ B cells or thymic T cell subsets. In the spleen, by contrast, we find that individual splenic B cell populations, including transitional, marginal zone, and follicular mature B cell subsets, were largely unaffected by smoke exposure, but smoking did skew splenic CD4+:CD8+ T cell ratio to favor CD8+ T cells compared to sham controls. However, smoke exposure also had little or no effect on lymphocyte function ex vivo. Interestingly, smoking-induced alterations in lymphocyte populations observed at 12 weeks were lost when smoke exposure was stopped for six weeks. These data provide evidence that smoke exposure causes significant changes in lymphocyte populations that can largely be reversed after six weeks without smoking.
Hierarchy of T cell lineage decision is regulated by thymic self-reactive signaling (36.45)
Authors: Marcus Assaf , Friedmann-Morvinski Dinorah , Elinav Eran , Waks Tova , Eshhar Zelig 
Published: January 2023

Abstract
During T cell development, thymic recognition of self antigens leads to negative selection of effector T cells with high TCR avidity. Similar interactions are implicated with emergence of regulatory subsets, including Tregs, NKT, and CD8αα cells. How the degree of self-reactive signaling coordinates the development of the effector and regulatory subpopulations is not fully understood. To elucidate this, we employed transgenic mice, featuring gradually increasing self-reactivity by expression of different levels of a cross-reactive tripartite chimeric receptor targeting 2,4,6-trinitrophenol (TNP). In these mice, increasing cell self-reactivity inversely correlated with effector cell numbers, and led to skewing towards CD4 phenotype, compatible with the kinetic signaling model. In parallel, coreceptor levels of expression were diminished in correlation with gradually increasing self-reactivity, reflecting coreceptor tuning. Higher levels of self-reactive signaling promoted the thymic expansion of CD8αα and NKT cells. T cells with the highest self-reactive TPCR featured defective TCR rearrangement stemming from down regulation of RAG1, RAG2 and PTα. Altogether, we demonstrate a hierarchical order in coping of the immune system with auto-reactivity. In case of weak self-reactivity, coreceptor tuning is implemented, while in stronger self-reactivity, regulatory subsets develop, as possible means of modulating dangerous autoreactive cells into protective guardians of host.
Expanded γδ T cell populations in absence of transcription factor PU.1 (36.49)
Authors: Jabeen Rukhsana , Chang Hua-Chen , Nutt Stephen , Kaplan Mark 
Published: January 2023

Abstract
T cell development is characterized by a succession of developmental stages that lead to the generation of mature αβ and γδ T cells. γδ T cells are considered innate cells that critically contribute to host defense. PU.1, an Ets family transcription factor, also identified as the spleen focus forming virus proviral integration site-1 (Sfpi-1) is essential for early stages of T cell development and is down regulated during the pro T-cell stage. PU.1 is expressed in Th2 cells but not Th1 cells. Expression of PU.1 in other T cell subsets has not been studied extensively. In this study, we show that PU.1 is expressed in γδ T cells, and in mice that specifically lack PU.1 in T cells using an lck-Cre transgene with a conditional Sfpi1 allele (Sfpilck-/-) there are increased numbers of γδ T cells in spleen, thymus and in the intestine when compared to wild type mice. The increase in γδ T cell numbers in PU.1 deficient mice is reflected in several subsets examined (Vγ2T, Vγ3T and Vδ4T). In mice where PU.1 was deleted using a CD4-Cre transgene, the expansion of γδ T cell numbers was restricted to the intestinal population. PU.1-deficient γδ T cells secrete higher levels of IL-17 than wild type cells, but similar levels of IFN-γ. Thus, our data show that PU.1 is expressed in γδ T cells and that deletion of PU.1 results in γδ T cell expansion. This suggests that PU.1 has a negative influence on γδ T cell development or expansion.
Bcl11b: a novel regulator of T-lineage commitment (36.50)
Authors: Li Long , Rothenberg Ellen 
Published: January 2023

Abstract
Commitment of HSC to a T-lineage fate is driven by a network of transcription factors and environment cues. Transcription factor Bcl11b is expected to be a crucial component of the network. Bcl11b is an essential regulator for T-cell development. However, little is known about how Bcl11b works in the commitment stage of T-cell development. Using an in vitro growth system, we have found that under certain conditions Bcl11b-deficient pre-T cells fail to pass the DN2/DN3 transition, which is the lineage commitment step in T-cell development. Instead, Bcl11b-deficient cells continuously grow at DN1-like and DN2A-like stages for more than twenty days, while wild-type controls can develop normally to DN3 and DN4 cells. Unlike their wild-type counterparts, the long-term Bcl11b-deficient cells still possess developmental plasticity with an IKDC-like population growing out from the cells. Gene expression profile reveals that Bcl11b-deficient cells express T-cell identity genes including Cd3e and Lck, and continue to silence some important genes associated with major developmental alternatives, such as B-cell factors; however, they fail to turn off stem cell genes and some lineage-regulators, such as Scl, Lyl1, Gfi1b, Id2, Il2rb, Zbtb16 and Bcl11a. The results indicate that Bcl11b plays a major role in T-lineage commitment by controlling the correct exit of T-cell precursors from a progenitor cell state. No other factor has been shown to have this distinctive function.
Membrane localization of the avian chB6 alloantigen (36.62)
Authors: Funk Phillip , Sanderson Bailey , Cheatham Terah 
Published: January 2023

Abstract
Chickens are one of the classic models of vertebrate immunity. We have been interested in the role of the alloantigen chB6 (formerly called BU1) in the development of B cells within the bursa and have presented evidence that chB6 can trigger apoptosis. Furthermore, the pathway that triggers apoptosis is similar to that triggered by FAS, with caspase 8 as an initiator, caspases 9 and 3 as later caspases, and bcl-xl functioning as an inhibitor of apoptosis. We have been unable to demonstrate a steady state association of chB6 and caspase 8 in DT40, so the mechanism of caspase 8 activation remains unclear. Other investigators have shown that FAS segregates into lipid rafts in type I cells and this is correlated with death signaling. In addition, FAS ligation leads to the formation of distinct signaling complexes termed SPOTS. Using immunofluorescence, we observed that chB6, when cross-linked by secondary antibodies, is found in patchy areas on DT40 cells reminiscent of SPOTS. By double labeling with fluorescent cholera toxin B, we show that chB6 co-localizes with lipid raft areas of the DT40 membrane and will be internalized by the cells. This suggests an active distribution of chB6 in the membrane and it may be preferentially loaded into lipid rafts along with BCR in avian cells. This work offers a new insight into the signaling via chB6. This work supported by a grant from the DePaul University Research Council.
Basis for lineage-specific control of PTEN expression by Rpl22 (36.64)
Authors: Stadanlick Jason , Lee Sang-Yun , Wiest David 
Published: January 2023

Abstract
Mutations in a number of ribosomal proteins impair erythropoiesis (e.g., Rps19 mutations in Diamond Blackfan Anemia); however, such mutations have not been reported to disrupt T cell development. We have shown that ablation of ribosomal protein L22 (Rpl22) results in a strikingly specific defect in T cell development, selectively arresting αβ lineage cells through translational de-repression of the tumor suppressor p53 while sparing cells of the γδ-lineage. We performed comparative analysis of Rpl22-/- αβ and γδ precursors to assess the basis for lineage restriction of the blockade. Initial studies revealed a marked decrease in expression of PTEN in mixed-lineage CD4-8- (DN) progenitors from Rpl22-/- mice. This result is paradoxical, as PTEN is a positive regulator of p53 expression, yet its expression is reduced in cells where p53 is elevated. We hypothesized that the reduction in PTEN and the increase in p53 were actually occurring in distinct populations within the DN pool. Indeed, we found that PTEN levels were not reduced in purified αβ-lineage DN3 thymocytes from Rpl22-/- mice, suggesting the loss of PTEN occurs specifically in γδ lineage cells. In agreement, real-time PCR analysis revealed that PTEN mRNA levels are reduced in Rpl22-/- γδ T cells. Taken together, these data indicate that one important factor contributing to the sparing of γδ lineage development in Rpl22-/- mice is the selective reduction in γδ lineage cells of PTEN expression, which destabilizes p53.
Antecedent influenza virus infection enhances the innate immune response to secondary Haemophilus infection in a porcine co-infection model. (37.11)
Authors: Loving Crystal , Brockmeier Susan , Vincent Amy 
Published: January 2023

Abstract
The increasing number of annual influenza (Flu) cases, coupled with the recent Flu pandemic, has amplified concerns about the impact of Flu on human and animal health. It is appreciated that Flu is complicated by secondary bacterial infection. Tracheal epithelial cells (TEC) and pulmonary macrophages (Mac) respond to infection with proinflammatory cytokines for controlling pathogen spread; however, exacerbated responses can lead to immunopathology that may be detrimental to the host. The extent to which antecedent Flu alters TEC and Mac responses to secondary stimulation is poorly understood. Pigs serve as a model for Flu infection, and secondary infection with Haemophilus parasuis (Hps) provides a useful co-infection model for evaluating host responses. Groups of pigs were infected with Flu virus and 5-days later infected with Hps (Flu/Hps). Non-infected, Flu-only and Hps-only groups served as controls. Pigs were necropsied 1 day following Hps inoculation and results show Hps colonization was higher in the nose and lungs of Flu/Hps pigs compared to Hps-only pigs. In Flu/Hps pigs, IL-8, IL-6 and IL-1β protein levels were increased in the lung, and TEC and Mac cytokine mRNA expression levels were significantly increased over Flu-only and Hps-only pigs. Also, TEC and Mac from 5-day post-Flu pigs exhibited dysregulated innate immune responses to secondary Hps exposure in vitro, providing additional evidence that Flu infection alters host responses to secondary stimulation.
New mechanism of innate immunity mediated by human defensin α-1 against Trypanosoma cruzi (37.2)
Authors: Cardenas Tatiana , Kleshchenko Yuliya , Madison M. , Nde Pius , Johnson Candice , Furtak Vyacheslav , Lima Maria , Villalta Fernando 
Published: January 2023

Abstract
The mechanisms of innate immunity against protozoan parasites that cause significant diseases are very limited. Here we show that human defensin α-1 plays a fundamental role in the initiation of innate immune responses to Trypanosoma cruzi. We demonstrate that human epithelial cells respond to early T. cruzi infection by up-regulating the expression and secretion of defensin α-1, which inhibits T. cruzi motility and prevents cellular infection. Human defensin α-1 inhibits trypomastigote motility of T. cruzi and infection at low micromolar concentrations, and this requires direct association of the defensin α-1 with the invasive trypanosome, which causes membrane depolarization and pore formation in the flagellar membrane. Moreover, defensin α-1 alters the flagellar axonemes, breaks both the flagellar membrane that attaches the flagellum to the trypanosome body and the flagellum thereby restricting trypanosome motility, which is required for trypanosome membrane penetration during cell entry. This is the first report showing that defensin α-1 disrupts the T. cruzi flagellum to compromise trypanosome motility and prevents cellular infection. Thus, defensin α-1 possess remarkably distinct modes of activity against protozoan parasites than bacteria and viruses, and their function may provide insights for the development of new antitrypanosomal strategies (supported by NIH grants AI AI080580 and AI007281)
Leishmania mexicana infection induces antibody responses to parasite surface glycolipids that can induce IL-10 and suppress IL-12 from macrophages (37.25)
Authors: Buxbaum Laurence 
Published: January 2023

Abstract
Chronic disease of mice caused by the protozoan parasite Leishmania mexicana requires IL-10 and FcγRIII. Immune complexes consisting of IgG bound to the surface of Leishmania amastigotes can induce IL-10 and suppress IL-12 production from macrophages. However, the targets of these antibodies and the kinetics of their production are not known. Several groups have attempted, without success, to identify surface proteins on the amastigote form of the parasite to which IgG can bind. Using ELISA and thin layer chromatography (TLC) immunoblot methods we now show that parasite glycoinositol phospholipids (GIPLs) of L. mexicana are recognized by IgG1 by 6 weeks of infection with a rapid increase between 14-16 wks, consistent with the timing of chronic disease in C57BL/6 mice vs. healing in FcγRIII KO mice. We found that a single prominent spot on TLC is recognized by mouse serum of infected mice and that the glycolipid has a glycosyl phosphatidylinositol (GPI) structure as assessed by GPI-PLC and GPI-PLD susceptibility. Alpha-mannosidase treatment changed the mobility of the recognized glycolipid, indicating that a branched mannose occurs in the structure, but is not required for IgG binding. Further characterization of the target glycolipids will have important implications for vaccine development as well as elucidating the poorly understood role of glycolipids in immunology. Funded by VA Merit, the University of Pennsylvania, and NIH R01-AI081717.
Characterizing mast cell clearance of Yersinia pestis (37.29)
Authors: Lambert Nathaniel , Langefitt Deanna , Nilles Matthew , Bradley David 
Published: January 2023

Abstract
Mast cells have been implicated in protective responses to infectious agents. Yersinia pestis is the causative agent of plague and considered a bioterrorism threat. We have previously demonstrated that B10.T(6R) mice were significantly more resistant to Y. pestis infection compared to Swiss Webster mice. Cromolyn sodium, an inhibitor of mast cell degranulation, abolishes resistance to Y. pestis infection in B10.T(6R) mice, suggesting a protective role for mast cells during Y. pestis infection. The ability of mast cells to internalize Y. pestis was assessed in P815 cells, a murine mast cell-like clone. Both wild-type and type three secretion system mutant strains of Y. pestis were not internalized. There was no visible degranulation of P815 cells cultured with Y. pestis compared to heavily degranulation with compound 48/80 treatment. To determine if Y. pestis may be inducing the release of preformed cytokines without visible degranulation, TNF-α levels were measured in supernatants from P815 cells infected with Y. pestis and S. typhimurium.Y. pestis did not induce any increase in TNF- α (&lt;8 ng/ml), while TNF-α levels were increased with S. typhimurium infection by 30 min and reached 21 ng/ml by 4 h. These findings provide an excellent model to investigate responses by mast cells to various bacteria, and possible functional differences in mast cells from different strains of mice.
Intravital imaging of Borrelia burgdorferi and murine innate immune cells during early cutaneous infection. (37.42)
Authors: Lavik John-Paul , Shukla Vipul , Wooten R. Mark 
Published: January 2023

Abstract
After tick transmission, the spirochete, Borrelia burgdorferi (Bb), remains at the skin inoculation site for up to 48 hours before spreading and causing Lyme disease. Bb surface agonists should elicit potent inflammation and clearance in skin. However, the ID50 is &lt;50 Bb, indicating efficient immunoevasion and suggesting that traditional in vitro models are inadequate for accurately characterizing Bb pathogenesis (i.e. most models display efficient Bb clearance by phagocytes). Thus, we have devised a confocal microscopy method for visualizing infectious fluorescent Bb in situ and in real-time. Here, we inject Bb into ear skin of anesthetized mice and collect four-dimensional data regarding Bb motility during natural infection. This data is complemented by quantitative PCR and histological analyses of the temporal fall and rise of spirochete numbers in vivo. By 4h, the majority of Bb at the injection site are immobile, while Bb adjacent to the site are highly motile. Two movement types are seen: 1) a back and forth shift that may aid Bb in finding an optimal migration path and 2) a directed run that navigates dermal structures. Analysis indicates an average Bb velocity of ≥100 um per minute in skin, which is &gt;10x faster than any immune cell velocities observed in our model. This suggests that Bb motility is a primary mechanism for host cell evasion and indicates our imaging techniques will allow true delineation of host-Bb interactions critical for Lyme disease development.
Mouse Beta-Defensin-1 Plays a Role in Influenza Innate Immunity (37.49)
Authors: Ryan Lisa , Diamond Gill 
Published: January 2023

Abstract
Beta-defensins (BD) are antimicrobial peptides that play a role in bridging innate and adaptive immune responses to infection. The most widely studied is hBD-2, which increases upon stimulation of epithelial cells with lipopolysaccharide (LPS). hBD-1 remains constitutively produced in spite of cytokine or LPS stimulation, but is stimulated by influenza virus in monocytes and plasmacytoid dendritic cells. C57Bl/6 male 8-12 week old mice (WT) and mice with mBD-1 (hBD-1 homologue) deleted (mBD-1-/- KO) were intranasally infected with 300 pfu/50µl of mouse-adapted Hong Kong 1968 influenza A H3N2 virus. Initially, KO mice lost significantly more weight than WT mice until day 5 when KO mice began to die (p ≤ 0.05). Most of the WT deaths occurred on days 8-16. KO mice died sooner, on days 5-10. At day 10, only 15% of KO mice survived compared with 45% of WT mice. After day 16, 10% of KO mice survived versus 18.2% of WT. Mortality of KO mice was significantly greater than that of WT mice (p = 0.028). UV-inactivated virus did not cause body weight loss or mortality in either strain. Although virus titers were equal 24 hr after infection, 3 days following infection the inflammatory cell influx was greater in KO mice compared with WT mice. By day 6, histology in these two strains was comparable, with a large lymphocytic infiltrate and hemorrhage in both strains, suggesting that beta-defensin-1 is important in controlling inflammation early in viral infection.
Combating pulmonary Coxiella burnetii infection: The role of innate immunity. (37.54)
Authors: Calverley Matthew , Read Amanda , Harmsen Allen 
Published: January 2023

Abstract
The innate immune system provides first line host defense. However, within the immune privileged site of the lung, immune response must be closely regulated. As a result, tissue resident alveolar macrophages (AM) are typically immunosuppressed. The intracellular bacteria Coxiella burnetii has been observed within AM during infection and little is known about the role of AM in C. burnetii infection. Therefore, the AM deserves focused study. We hypothesized that, due to the immunosuppressed state of resident AM, these macrophages are particularly susceptible to C. burnetii infection and provide a required niche for infection. Dye labeling techniques were employed to discriminate AM and C. burnetii, allowing for the determination of resident and infected cell populations. These techniques were corroborated with antibody labeling and the various populations were analyzed. We report here that resident AM are infected, even at low infective doses. Interestingly, a heterogeneous population of infected cells is also identifiable. This population is comprised of resident CD11c+ AM expressing CD11b and recruited CD11b+ cells expressing CD11c. These findings suggest CD11c expression serves as a marker of cells susceptible to C. burnetii infection. Identification of this susceptible population may aid vaccine development and prove relevant for treatment of other intracellular bacteria, such as, Mycobacterium tuberculosis and Legionella pneumophila.
CD56+ gamma delta T cells in the peripheral blood during HCV infection (38.15)
Authors: Epie Nicolas , Talwani Rohit , Armstrong Cheryl , Pauza C.David 
Published: January 2023

Abstract
Hepatitis C virus (HCV) is a chronic persistent infection that can cause hepatitis and hepatocellular carcinoma. HCV infection is less responsive to therapy among African Americans compared to Caucasians suggesting that underlying differences may impact disease progression. γδ T cells are present at levels differing by 5-fold among healthy Caucasian and African American, such differences might contribute to the outcomes disparity. We collected blood from African American adults with HCV infection and characterized γδ T cells in this group. Compared to controls, the HCV+ group had &gt; 2-fold higher levels of circulating γδ T cells of the Vδ+ subset, suggesting they were actively involved in the immune response to HCV. Surprisingly, the γδ T cells in HCV+ African Americans were lower than controls for the percentage of cells expressing CD56, a marker associated with cytotoxic effector function in this cell type. The patterns of γδ T cells in African Americans with HCV infection suggest that they participate in an active immune response against virus and that the CD56+ subset may be sequestered in tissue in an effort to block virus replication. Thus, γδ T cells may participate in the complex immune responses to HCV and their lower levels provide one potential explanation for the outcomes disparity among African Americans and Caucasians with HCV infection and liver disease.