bluuebunny/crossref_metadata_2025_split huggingface dataset:
PIK3IP1- A novel negative regulator of PI3K (IRM10P.743)
Authors: Uche Uzodinma , Kane Lawrence 
Published: January 2023

Abstract
Phosphatidylinositide-3-Kinases (PI3Ks) are a family of lipid kinases that play important intracellular signaling roles in cellular functions such as cell proliferation, motility, growth, intracellular trafficking, differentiation and survival. PI3K produces PIP3 which further facilitates the activation of downstream effectors such as Akt and PDK1. These effectors facilitate the cellular processes associated with PI3K activity. Conversely, because of the nature of PI3Ks roles, dysregulation of PI3K is implicated in many cancers. PTEN, SHIP and INPP4B are negative regulators of PI3K activity that function downstream of PI3K and have been shown to act as tumor suppressors. Recently, PI3K Interacting Protein 1 (PIK3IP1), a novel negative regulator that functions upstream and proximal to PI3K, has been identified. PIK3IP1, is a transmembrane protein that down-regulates PI3K activity, leading to reduced Akt phosphorylation. Our lab recently showed that PIK3IP1 can inhibit TCR signaling and TCR activation. To better understand the role of PIK3IP1 in T cells, we have begun to carefully define its expression pattern in various T cell subsets. In addition, we have developed a PIK3IP1 ecto-domain Fc fusion protein, which we are using to define possible ligands for PIK3IP1. Finally, we have obtained knockout mice lacking expression of PIK3IP1, to better define the requirements for PIK3IP1 in primary T cells.
Cytoskeletal stiffness controls the threshold of T cell activation (IRM10P.747)
Authors: Butte Manish , Bruce Marc , Thauland Timothy 
Published: January 2023

Abstract
T cells require a dynamic cytoskeleton to effectively scan antigen-presenting cells and become fully activated. To study the function of cytoskeletal changes as they occur in real time during T cell activation, we modified an atomic force microscope to deliver antigen via the cantilever, simultaneously ligating T-cell receptors (TCRs) and measuring changes in cytoskeletal mechanics. We show that antigenically naïve T cells are mechanically stiff and their cytoskeletal structures undergo rapid relaxation at the site of TCR ligation. In contrast, antigen-experienced memory and effector T cells are already soft prior to TCR triggering. We found that cytoskeletal relaxation is due to depolymerization of actin, is proportional to antigen dose, and requires proximal TCR signaling pathways but not ICAM-1:LFA-1 interaction. We identified pathways controlling the stiffness of naïve T cells, and blocking these pathways resulted in naïve T cells become soft even prior to TCR triggering. Moreover, these soft yet antigen-inexperienced T cells showed a reduced threshold for allo- and antigen-specific activation compared to controls. Our results highlight the functional importance of cytoskeletal stuctures in tuning T cell responses to spatially localized signals from APCs.
Down-modulation of tumor suppressor p53 by T cell receptor signaling is critical for antigen-specific T cell responses (IRM10P.737)
Authors: Watanabe Masashi , Moon Kyung duk , Vacchio Melanie , Hathcock Karen , Hodes Richard 
Published: January 2023

Abstract
We report here that antigen-specific proliferative responses of naïve and memory CD4 T cells require the down-modulation of tumor suppressor p53. In the absence of TCR signal, IL-2 induces a sustained increase in p53 protein, which prevents proliferative responses despite strong signaling through the IL-2 receptor. In contrast, TCR signaling results in early termination of p53 protein expression by decreasing p53 mRNA as well as by strong transcriptional induction of the p53-regulating protein Mdm2. Down-modulation of p53 in response to antigen stimulation is in fact critical for antigen-specific T cell proliferation; and preventing p53 degradation by inhibiting Mdm2 results in sustained p53 protein levels and prevents antigen-specific T cell proliferation. These studies elucidate a critical role of p53 as a negative regulator of T cell proliferation. It is the termination of p53 elevation by TCR signaling that allows proliferative responses to occur, enforcing antigen specificity.
Phosphatidylcholine as a metabolic cue for determining B cell fate and function (LYM6P.774)
Authors: Barrington Robert , Solodushko Viktoriya , Aragon Ileana , Brewer Joseph 
Published: January 2023

Abstract
In activated B cells, increased production of phosphatidylcholine (PtdCho), the most abundant cellular phospholipid, is handled primarily by the CDP-choline pathway. Previous studies revealed that CD19Cre-mediated deletion of CTP:phosphocholine cytidylyltransferase α (CCTα), the rate-limiting enzyme in the CDP-choline pathway, led to augmented IgM secretion and reduced IgG production, consistent with defective germinal center reactions. To more specifically assess the influence of PtdCho on B cell fate during germinal center and long-term humoral responses, we examined immune responses in Cγ1Cre CCTαflox mice. Serum IgG1 was undetectable in naïve Cγ1Cre CCTαflox mice, while levels of IgM and other IgG subclasses were similar in naïve Cγ1Cre CCTαflox and control mice. Following immunization with T cell-dependent antigen NP-KLH, control mice predictively generated high titer IgG anti-NP. In contrast, IgG anti-NP titers were markedly reduced in immunized Cγ1Cre CCTαflox mice. Interestingly, though antigen-specific IgM responses were comparable between Cγ1Cre CCTαflox and control mice, the IgM anti-NP response in Cγ1Cre CCTαflox mice failed to increase in affinity. Lastly, the frequency of antigen-experienced NP-specific B cells and antibody-secreting cells (ASC) were both reduced in Cγ1Cre CCTαflox mice compared with controls. These data indicate that PtdCho plays a pivotal role in the generation and persistence of both germinal center B cells and ASC.
First mitotic division programs naïve B cell for successive cell divisions (LYM6P.778)
Authors: Singh Amit , Zhang Yongqing , Wood William , Becker Kevin , Sen Ranjan 
Published: January 2023

Abstract
Transient activation via the B cell receptor (BCR) primes naïve B cells to respond more efficiently to CD40 signals, resulting in increased cell division over a 48hr time course. At this time point approximately 40% of primed B cells had undergone at least one division, as compared to 15% cells activated by anti-CD40 antibody alone. Cells that had divided once continued through several additional division cycles in the absence of exogenous stimuli, whereas cells that had not divided after the first 48hr required renewed anti-Ig signals to induce proliferation. These observations demonstrate that successful negotiation of the first mitosis make mature B cells permissive for signal-independent proliferation. Characteristics of once divided cells that give them this unique property will be presented and the implications for physiological responses of B cells will be discussed.
Dynamics of B cell subsets within the CNS during viral encephalomyelitis (LYM6P.779)
Authors: Disano Krista , Phares Timothy , Bergmann Cornelia 
Published: January 2023

Abstract
Central nervous system inflammation induced by viral infection and autoimmune disease results in the accumulation of plasmablasts. During neurotropic coronavirus infection, CD138+CD19+ plasmablasts are essential in preventing viral reemergence after initial T cell mediated control of infectious virus. This study characterizes the temporal dynamics and precursor relationships between B cell subsets within the infected central nervous system. Flow cytometry revealed that CD138- B cells recruited early displayed a naïve or early activated IgD+IgM+ phenotype. This population progressively declined coincident with an increase of IgD-IgM+ and isotype switched memory B cells and plasmablasts, suggesting early B cells differentiate locally or are replaced by newly recruited, more differentiated B cells. Ki-67 expression by CD138- B cells revealed proliferation in IgD+IgM+ B cells was minimal, while proliferation was substantially elevated in IgDloIgM+ and IgD-IgM+ cells, consistent with recruitment of peripherally proliferating B cells rather than local differentiation of naïve B cells. Nevertheless, a transient capacity of IgM+ and IgD+ B cells to enter the parenchyma early in infection suggests they may have an antibody independent role during central nervous system inflammation.
Long-term bone marrow IgM-producing plasmablasts are derived during acute infection and are maintained by active proliferation (LYM6P.767)
Authors: Papillion Amber , Winslow Gary 
Published: January 2023

Abstract
We have previously characterized a population of IgM-secreting B cells in the bone marrow (BM) of mice infected with the intracellular bacterium Ehrlichia muris (J. Immunol. 186:1011). The BM cells are responsible for IgM production, which is sufficient to maintain long-term immunity to fatal infection. In the present study, we have investigated the ontogeny and maintenance of the B cell population. We utilized AID-Cre-ERT2 X Rosa26loxP-EYFP mice (Nat. Immunol. 10:1292) to irreversibly mark activation-induced cytidine deaminase (AID)-expressing B cells. Following tamoxifen administration on day 10 post-infection, the time of peak spleen CD11c-positive plasmablast response, we detected EYFP+ CD138+ IgM+ BM cells for at least as long as 100 days post-infection; the EYFP+ cells were maintained at frequencies as high as 25% of the BM IgM+ B cells. These data indicated that the BM B cells were likely derived from T cell-independent spleen plasmablasts, and constituted a long-lived population. BrdU incorporation studies also demonstrated that the majority of the IgM+ cells were actively proliferating, indicating that B cells were plasmablasts. Finally, antibody-mediated blocking of CD40:CD40L signaling during acute infection did not impact the generation of the BM plasmablasts, indicating that the plasmablasts were likely generated in the absence of T cell help. These findings underscore the importance of BM IgM plasmablasts in long-term humoral immunity and host defense.
The macrophage-derived proteins murine RELMα and human resistin regulate host immunity to helminth infection (MPF3P.801)
Authors: Nair Meera 
Published: January 2023

Abstract
Th2 cells are essential for protective immunity to helminths but also contribute to chronic inflammation. Here we identify the REsistin-Like Molecules RELMα and Resistin as critical mediators of this balance between helminth Th2-mediated immunity and inflammation in both murine infection and human studies. Following infection with Nippostrongylus brasiliensis, we observed significant macrophage expression of RELMα in the lungs. When RELMα-/- mice were infected with N. brasiliensis, there were increased Th2-type responses, accelerated worm expulsion and exacerbated lung inflammation compared to wild-type mice, implicating a role for RELMα in dampening Th2 immune responses. Selective depletion of macrophages in RELMα-/- mice ameliorated N. brasiliensis-induced chronic lung inflammation, suggesting that RELMα modulates inflammation through effects on macrophages. In new translational studies, we investigated the function of human Resistin (hResistin) which shares sequence homology with RELMα. Employing transgenic mice that express hResistin, we observed increased macrophage expression of hResistin in N. brasiliensis-infected lungs. Moreover, hResistin inhibited Th2 immune responses and immunity to N. brasiliensis. Finally, we observed a strong correlation between parasite number and serum Resistin levels in a population of helminth-infected patients (n=46). Taken together, these studies identify a new RELM-mediated regulatory pathway in helminth immunity and inflammation.
Effect of CCL1 antisense oligodeoxynucleotides (ODN) on MRSA infection in subacutely burned mice (SB-mice) (MPF3P.810)
Authors: Kobayashi Makiko , Ito Ichiaki , Nishiguchi Tomoki , Herndon David , Suzuki Fujio 
Published: January 2023

Abstract
Staphylococcus aureus is frequently isolated from subacutely burned patients, and these infections easily develop into severe sepsis. M2bMφ have been characterized as the responsible cells on the increased susceptibility of SB-mice to staphylococcal infections, and SB-mice are carriers of M2bMφ. In this study, we tried to protect SB-mice (mice 10 to 30 days after burn injury) from a lethal dose infection of MRSA using CCL1 antisense ODN (an inhibitor of M2bMφ). Mice, 14 days after burn injury (20% total body surface area 3rd degree burns), were infected with 2 x 106 CFU/mouse of MRSA. Then, these mice were treated s.c. with 10 μg/mouse of CCL1 antisense ODN twice a day for 3 days (treated mice). As control mice, SB-mice were treated with scrambled ODN. The protective effect of the ODN against MRSA infection was evaluated by a reduction in the mortality rates of treated mice as compared with that of control mice. Also, bacterial growth in various organs of treated mice was compared with those of controls. In the results, all control mice died within 7 days of MRSA infection, while all treated mice were still alive after 7 days with the same infection. Bacteria grew in the liver, spleen and kidneys of control mice. However, the pathogen did not grow significantly in these organs of treated mice. These results indicate that sepsis caused by a lethal dose of MRSA infection in SB-mice is controlled by treatment with CCL1 antisense ODN.
Early in vivo infection dynamics in non-human primates infected with Mycobacterium tuberculosis (MPF3P.813)
Authors: Cadena Anthony , Martin Constance , Fortune Sarah , Flynn JoAnne 
Published: January 2023

Abstract
Tuberculosis (TB) continues to pose a significant health risk to morbidity and mortality worldwide. The vast majority of individuals infected with M. tuberculosis, the causative agent of TB, contain the infection as clinically asymptomatic latent TB. A small minority of people do not and either present with primary active disease or reactivate over their lifetime. By examining early events in infection at the local lesion level, we aim to uncover some of the basis for the observed spectrum of TB disease and host outcome. Using genetically barcoded M. tuberculosis, serial PET/CT lesion imaging, and tools to analyze each granuloma at the microbial and immunological level, we are tracking local lesion development and dissemination at various stages of infection in cynomolgus macaques. Background studies have revealed that granulomas are dynamic entities that largely arise from single bacteria. We hypothesize that early interactions between M. tuberculosis and host immune components contribute to lesion heterogeneity and that these initial events influence infection outcome. We performed a small reinfection experiment with M. tuberculosis barcoded strains. Our data suggests that primary infection limits secondary infection lesion development and dissemination. Further analysis of this study is ongoing. Probing the mechanisms that underlie the human TB spectrum will reveal crucial stages of infection that can be exploited for novel therapeutic design.
The TLR2 signaling pathway is activated by sporozoites and suppresses intrahepatic parasite development (MPF3P.815)
Authors: Xu Wenyue , Zheng Hong , Tan Zhangping , Zhou TaoLi 
Published: January 2023

Abstract
TLRs (Toll-like receptors) play an important role in the initiation of innate immune responses against invading microorganisms. Although several TLRs have been reported to be involved in the innate immune response against the blood-stage of malaria parasites, the role of TLRs in the development of the pre-erythrocytic stage is still largely unknown. Here, we find that sporozoite lysate can significantly activate TLR2. Further studies show that sporozoite lysate can be recognized by either TLR2 homodimers or TLR2/1 and TLR2/6 heterodimers and induce macrophages to release proinflammatory cytokines in a TLR2-dependent manner. Interestingly, the TLR2 signaling pathway can significantly suppress the development of the pre-erythrocytic stage, and the administration of TLR2 agonists greatly reduced the liver parasite load of mice challenged with sporozoites. Additionally, the observed higher level of parasite burden in TLR2-/- mice is found to be closely associated with a reduction in proinflammatory cytokines in the liver.Therefore, we provide the first evidence that sporozoites can activate the TLR2 signaling pathway, which in turn significantly inhibits the intrahepatic parasites. This may not only help us to understand the mechanism of the innate immune response against pre-erythrocytic stage of malaria parasite but may also provide us with novel clues to design preventive anti-malaria therapies.
The protective role of macrophages in Francisella tularensis infection (MPF3P.819)
Authors: Steiner Donald , Furuya Yoichi , Metzger Dennis 
Published: January 2023

Abstract
Francisella tularensis causes lethal pneumonia following infection of the lungs. F. tularensis is considered to be an intracellular pathogen that targets macrophages for replication. We therefore hypothesized that depletion of alveolar macrophages would impede bacterial replication and improve host survival. However, it was found that macrophages are essential for survival of F. tularensis infection and depletion of these cells reduced survival rates following infection. Mice with a macrophage-specific defect in interferon gamma (IFN-γ) signaling (MIIG mice) were also highly sensitive to infection, exhibiting reduced survival rates, reduced mean time to death, and increased bacterial burdens in lungs, liver, and spleen relative to wild-type mice. We have previously found that treatment with exogenous interleukin 12 (IL-12) protects against F. tularensis infection; this protection was lost in MIIG mice. MIIG mice also exhibited reduced neutrophil recruitment to the lungs following infection. Systemic neutrophil depletion was found to render mice highly sensitive to pneumonic F. tularensis infection. Furthermore, IL-12-mediated protection required NADPH activity. These results indicate that lung macrophages serve a critical protective role in pneumonic F. tularensis infection. Macrophages require IFN-γ signaling to mediate protection, which ultimately results in recruitment of neutrophils to further aid in survival from infection.
Mycobacterium tuberculosis early secreted antigenic target of 6 kDa (ESAT-6) induces IL-6 production by macrophages via STAT3 (MPF3P.820)
Authors: Jung Bock-Gie , Wang Xisheng , Yi Na , Barnes Peter , Samten Buka 
Published: January 2023

Abstract
Early secreted antigenic target of 6 kDa (ESAT-6) of Mycobacterium tuberculosis (Mtb) is a major virulence factor. Mtb-induced proinflammatory cytokine IL-6 inhibits macrophage responses to IFN-γ and contributes to the survival of Mtb. To explore the role of ESAT-6 in Mtb infection, we studied if ESAT-6 induces IL-6 production by macrophages. Incubation of mouse bone marrow-derived monocytes (BMDM) with ESAT-6 induced IL-6 production in dose and time dependent manner. However, culture filtrate protein of 10 kDa (CFP10) and antigen 85A (Ag85A) of Mtb did not induce IL-6 production, suggesting a specific effect of ESAT-6 on IL-6 production. Likewise, ESAT-6 but not CFP10 and Ag85A induced IL-6 secretion by human peripheral blood derived monocytes. Polymyxin B inhibited LPS but not ESAT-6 induced IL-6 secretion by macrophages refuting the possible role of LPS contamination in ESAT-6. ESAT-6 but not Pam3CSK4, a TLR2 agonist, stimulated IL-6 production by TLR2 knockout BMDM, indicating that this effect of ESAT-6 is TLR2 independent. To explore the signaling pathway of this, we examined the role of STAT3 since ESAT-6 induced activation of STAT3 in BMDM. Preincubation of cells with Stattic and S31-201, STAT3 inhibitors, but not rapamycin and DMSO (vehicle) inhibited ESAT-6 induced IL-6 expression by BMDM both at mRNA and protein level in a dose dependent manner without affecting cell viability. Thus, our results suggest that ESAT-6 induces IL-6 production in macrophages via STAT3.
Characterization of signaling pathways activated by helminth antigens in macrophages (MPF3P.808)
Authors: Valderrama-Carvajal Hector Francisco , Martínez-Saucedo Diana , Romero-Diaz Monica , Ruiz-Azuara Lena , Padilla-Viveros America , Padierna-Mota Laura , Canale-Zambrano Juan Carlos , Terrazas Luis I. 
Published: January 2023

Abstract
Helminths parasites modulate or escape their host’s immune response by different molecular and cellular strategies. One of these is through the interaction of different molecules from their surface with cellular membrane elements of immune cells, modulating signaling pathways. These parasites trigger, control and modulate the early response of macrophages and dendritic cells (DC). The aim of this study is to elucidate the macrophage signaling pathways that are activated in response to a Helminth Parasitic Antigen Fractions (HPAFs) in vitro. Our data show that HPAFs have a biological effect on macrophages. WB analysis using specific anti-phospho-antibodies, showed that the HPAFs can signalize in a time dependent manner. In addition, immunofluorescence experiments showed that HPAFs promote a significant change in macrophages morphology. Different reports indicate that the chemoattraction and change of morphology of the macrophages is an essential step in the host response to different infections. We evaluated the effect of HPAFs on the transcriptional regulation of downstream target genes. Our PCR studies showed that HPAFs-stimulated macrophages could regulate downstream target genes such as TLR-4, Arg-1, Ym-1 and iNOS, showing that HPAFs regulate important signaling pathways in macrophages. Our results suggest that HPAFs may contain molecules that could interact with membrane molecules, activating signaling pathways that are involved in the regulation of the immune response.
A Salmonella-encoded microRNA-like RNA facilitates bacterial invasion and intracellular replication via suppressing host cell inducible nitric oxide synthase (MPF3P.809)
Authors: Gu Hongwei , Zhang Tianfu , Li Donghai , Liu Fenyong , Zhang Chen-Yu , Zen Ke 
Published: January 2023

Abstract
Salmonella has developed a sophisticated machinery to promote virulence and survival. Here we show that Salmonella can hijack mammalian cell non-classical miRNA processing machinery to further process their non-coding RNAs into miRNA-like RNAs that modulate host cell function. Using Solexa deep sequencing, we detected a panel of 19-24nt Salmonella-derived ncRNA fragments in human colonic epithelial HT-29 cells following Salmonella infection. The fragment with the highest copy number, Sal-1, was validated by qRT-PCR and northern blot analysis. With seven copies in the S. enteritidis genome, Sal-1 has a stem structure-containing precursor with a free energy of ΔG= -26.1 kcal/mol. The processing of the Sal-1 “primary” /“precursor” to the mature Sal-1 in Salmonella-infected cells is Dicer-independent but Argonaute 2-dependent. Functionally, Sal-1 targets the expression of epithelial cell inducible nitric oxide synthase (iNOS) and thus reduces the NO production and bacterial resistance of host cells. Expression or depletion of Sal-1 in mouse colonic epithelium significantly enhanced or reduced Salmonella infection in mice, respectively. Finally, the enhancement of Salmonella infection in mice by Sal-1 was completely abolished by expressing a mutant iNOS isoform that had normal NO generation but could not be targeted by Sal-1. Our results show for the first time that Salmonella can produce functional miRNA-like RNAs, which may represent a novel class of virulence factors.