bluuebunny/crossref_metadata_2025_split huggingface dataset:
Extracellular ST6Gal-1 calibrates B cell IgG production by cell non-autonomous extrinsic sialylation
Authors: Irons Eric Edward , Punch Patrick Raymond , Lau Joseph T.Y. 
Published: January 2023

Abstract
Cell surface glycans are well-positioned to modify receptor interactions and their downstream biological outcomes. Although canonical glycosylation occurs intracellularly, glycosyltransferases also exist in the blood and can catalyze extracellular reactions with platelet-derived sugars. We have recently reported that such extrinsic glycosylation by the sialyltransferase ST6Gal-1 enhances survival and BCR signaling in immature B cells. Here, we report that mice lacking extrinsic ST6Gal-1 had reduced total and antigen-specific IgG after bone marrow transplantation, despite unaltered IgG half-life and reconstitution of mature B cells and plasma cells. Rather, this deficiency was accompanied by reduced IgG+ splenic B cells and impaired per-cell IgG secretion after BCR stimulation. In vitro, extrinsic sialylation of immature B cells with recombinant ST6Gal-1 enhanced expression of IgM, IgD, and CD86, and potentiated IgG production upon stimulation. Surprisingly, this was not associated with increased IgG germline transcripts or isotype switching, but more robust antigen-induced proliferation, generating more IgG-producing cells. In vivo, hydrodynamic transfection with St6gal1 DNA resulted in an increase in total serum IgG. Finally, infusion of recombinant ST6Gal-1 enlarged splenic follicles and the follicular B cell population, highlighting therapeutic potential in modifying B cell development. Currently, vaccine adjuvants rely on mechanical or inflammatory properties to trigger an immune response. Our results suggest the manipulation of a bloodborne sialyltransferase may be a novel B cell-targeted, biological strategy to boost vaccine-induced and overall IgG production.
Investigating Transcriptional Regulators of Memory T Follicular Helper Cells
Authors: Deng Tianda , Shaw Laura , Yu Bingfei , Nguyen Quynh P , Hedrick Stephen M , Goldrath Ananda W 
Published: January 2023

Abstract
Generation of T-cell memory is crucial in conferring vaccine-induced immunity, particularly against pathogens where neutralizing antibodies alone are insufficient at providing long-term protection. While great advances have been made in understanding the generation and maintenance of memory CD8+ T cells and B cells, mechanisms underlying the generation of memory CD4+ T cells have remained relatively elusive. This limitation is in part due to the multi-potency and lineage plasticity exhibited by CD4+ T helper (TH) cells. Using the LCMV viral infection model, we show that the T follicular helper (TFH) subset are the predominant CD4+ memory T cell type based on its relative abundance following pathogen elimination as well as its multi-potent potential upon antigen re-challenge. This multi-potency of TFH memory cells during secondary challenge has also been observed in influenza infection and acute bacterial infection, suggesting that the TFH memory subset is most capable of providing a comprehensive and robust secondary response. From advancements in CD8+ memory T cell studies, it has become clear that transcription factors (TF) serve as crucial arbiters for the cell-fate decisions between short-lived effector and memory. To investigate the transcriptional mechanisms underlying TFH formation, we employed a novel bioinformatics analysis utilizing the PageRank algorithm that combines both RNA-seq and ATAC-seq and have identified putative transcriptional regulators of memory TFH differentiation. Further understanding of TFH memory formation will undoubtedly unveil new insights into CD4+ T cell memory in hopes of improving vaccine-based immunity.
Mechanistic investigations of Granzyme A-mediated γ9δ2 T cell TB protective effects
Authors: Rasi Valerio , Xia Mei , Wood David C , Eickhoff Christopher S , Hoft Daniel F 
Published: January 2023

Abstract
One fourth of the world population is infected with Mycobacterium tuberculosis (Mtb). Currently, BCG strains are the only vaccines available to protect against tuberculosis (TB). Our lab has identified γδ T cells that secrete Granzyme A (GzmA) with TB protective effects. GzmA when released by TB-specific γδ T cells has been shown to inhibit the intracellular replication of the pathogen. To elucidate the mechanism(s) involved in this inhibition, the lab has purified human GzmA. The effects of this highly purified GzmA on mycobacterial replication inside human macrophages are being investigated using systems biology. A 2D-DIGE proteomic approach of PBMC-adherent cells has been performed to identify putative pathways involved in the control of mycobacterial replication. Our preliminary analysis of two PPD+ volunteers indicates that ER-stress responses (HSPA5, HSP90B1, P4HB, PDIA3) and purinergic channel receptor activation (ATP5B/C1/D/H/O) may be important for GzmA-mediated intracellular mycobacterial inhibition. Verification of these results is being performed to confirm the overall mechanism, and to exclude unrelated signals. Elucidation of the detailed pathways involved in pathogen clearance could lead to the development of novel chemotherapeutic and/or immunotherapeutic approaches for control of Mtb infection.
Circulating Memory is sufficient for protective immunity to secondary infection with Chlamydia
Authors: Labuda Jasmine C , McSorley Stephen J 
Published: January 2023

Abstract
Chlamydia trachomatis is the most prevalent bacterial STI worldwide and yet no vaccine currently exists to protect the public from this reproductive tract pathogen. Recent reports suggest that Tissue Resident Memory (TRM) T cells are essential for vaccine-induced protection against Chlamydia trachomatis in a mouse infection model. TRM T cells have also been implicated in protective immunity to other reproductive tract pathogens, including Herpes Simplex Virus. Here, we examine a requirement for circulating versus resident memory in protection against secondary infection with Chlamydia muridarum (Cm). When FTY720 was used to block memory lymphocyte circulation, protection against secondary infection was unaltered, demonstrating that local resident mechanisms within the female reproductive tract are sufficient for secondary protection. However, parabiosis surgery of memory and naïve mice demonstrated that naïve mice receiving circulating memory were also fully protected from Cm challenge, indicating that TRM are dispensable for protection. Ongoing experiments are examining the protective capacity of both TRM T cells and circulating memory and whether memory lymphocyte cluster (MLC) formation within the reproductive tract is an essential component of naturally acquired or transferred protective memory. Understanding the differential contribution of resident versus circulating memory to protective responses is vital for the development of new vaccines against Chlamydia infection.
Drug treatment of tuberculosis diminishes but does not abolish the protection against secondary M. tuberculosis challenge
Authors: Ganchua Sharie Keanne C , Cadena Anthony M , Hopkins Forrest F , Fortune Sarah , Flynn JoAnne L 
Published: January 2023

Abstract
Early human studies found that individuals with latent M. tuberculosis (Mtb) infection are less likely to develop active tuberculosis (TB) compared to naïve individuals with similar levels of exposure. Using Mtb-barcoded libraries (Lib A - first infection; Lib B - second infection), we showed that an existing Mtb infection in cynomolgus macaques protects against the establishment and progression of a second Mtb challenge. Studies suggest that humans treated for active TB are at higher risk for developing disease following reinfection. Therefore we hypothesized that drug treatment would compromise the protection against a second Mtb infection. To test this hypothesis, we treated macaques infected with Lib A with anti-TB drugs for three months before infecting with Lib B. As a control, a group of macaques were infected with both Lib A and B following the same timeline but without drug treatment. In both groups, the number of granulomas arising from the second infection (Lib B) was significantly fewer than the number of granulomas from the first infection (Lib A). Comparing with the naïve group from our previous study, both drug and non-drug treated groups had significantly fewer live bacteria in the Lib B granulomas albeit the drug treated group had &gt;10x higher bacterial burden than the untreated group. The Lib B granulomas in both groups were smaller and less inflammed (determined by PET CT) compared to granulomas from the naïve animals. No difference in the T cell response in Lib B granulomas was found in both drug and non-drug treated groups. These data suggest that the protection conferred by the first infection to the secondary Mtb challenge remains intact and that bacteria from the second infection were rapidly controlled regardless of treatment.
Resistance to inflammasome-mediated nitric oxide production is involved in Diffuse Cutaneous Leishmaniasis
Authors: Quirino Gustavo Fernando Silva , Santos Leonardo Lima , Borges Valeria Matos , Zamboni Dario Simoes 
Published: January 2023

Abstract
Leishmania amazonensis is one of the etiological agents of Cutaneous Leishmaniasis in Brazil. Infected individuals can present different forms of the disease, such as the Localized Cutaneous Leishmaniasis (LCL), characterized by round papules in the skin and the Diffuse Cutaneous Leishmanisis (DCL), a more severe form of the disease, characterized by multiple nodules in the skin, which are full of parasites. We have reported the protective function of the NLRP3 inflammasome during L. amazonensis infection in mouse, thus we aimed to evaluate if the inflammasome is involved in the determination of the LCL or DCL disease. We observed that skin biopsies of patients with DCL lesions present upregulation of inflammasome genes such as ASC, CASP1 and IL18. However, IL-1b and IL-18 levels in the plasma of LCL and DCL patients were similar. We used in vitro and mouse models to evaluate if the inflammasome is involved in the determination of the LCL or DCL. Macrophages do not differ in their ability to produce inflammasome-dependent IL-1b after infection with LCL and DCL. The inflammasome is involved in the control of LCL proliferation, but DCL isolates bypass the restrictive function of this platform both in vitro and in vivo. Further analysis showed that DCL isolates are resistant to inflammasome-mediated nitric oxide production. These data suggest that the resistance to the inflammasome effector functions may underlie the development of controlled (LCL) or disseminated (DCL) Leishmaniasis. We conclude that parasite-intrinsic factors related to resistance to the inflammasome might determine the outcome L. amazonensis infection.
Alveolar macrophage maturation is required for efficient killing of GBS in the lung
Authors: Lund Sean J , Patras Kathryn A , Yamamura Asami , Hernandez Gilberto , Lakhdari Omar , Nizet Victor , Prince Lawrence S 
Published: January 2023

Abstract
Group B Streptococcus (GBS) is the most common pathogen in neonates but rarely causes disease in adults. GBS causes pneumonia in newborns, suggesting a defect in lung innate immunity at birth. Using a novel neonatal mouse model of GBS pneumonia, we showed that newborn mice have reduced killing of GBS in the lung and more severe and persistent lung injury. Here we test the hypothesis that defects in alveolar macrophage (AM) maturation in newborns leads to GBS susceptibility. Clodronate depletion of AM from adult mice prevented GBS killing, supporting the requirement of AM for GBS protection. AM maturation and function requires GM-CSF, which is abundantly expressed in the lung. While AM maturation occurred on day 4 in WT mice, GM-CSF knockout mice (Csf2−/−) failed to develop AM. Consistent with the role of AM in GBS immunity, neonatal Csf2−/− mice had reduced GBS killing and lung macrophages failed to phagocytose GBS. Csf2−/− macrophages also had reduced expression of multiple Siglecs, cell surface receptors implicated in protection against encapsulated bacteria. Newborn lung macrophages expressed primarily Siglec-E (SigE), whereas expression of other Siglecs were only detected in more mature AM. We used SigE−/− mice to test its role in neonatal GBS pneumonia. GBS killing in SigE−/− neonates was similar to WT. However SigE−/− macrophages appeared to phagocytose GBS more efficiently in vivo, suggesting GBS may employ SigE to avoid detection by neonatal macrophages. Our data show that mature alveolar macrophages are required for protection against pulmonary GBS infection and potentially implicate the developmental regulation of macrophage Siglec expression in neonatal lung immunity.
Exploiting the molecular mimicry of Non-typeable Haemophilus influenzae with ketodeoxynonulosonic acid: Confusing the bacterium in its own game
Authors: Saha Sudeshna , Coady Alison , Choudhury Biswa , Chen Xi , Ram Sanjay , Nizet Victor , Varki Ajit 
Published: January 2023

Abstract
The distinctly human mucosal commensal and opportunistic pathogen non-typeable Haemophilus influenzae (NTHi) is frequently responsible for acute exacerbations of chronic obstructive pulmonary disease (COPD) in adults, and causes otitis media in infants. A key tool in this organism’s pathogenic arsenal is its ability to mimic glycans on human cells, which like all vertebrate cells, display diverse glycans with terminal 9-carbon-backbone monosaccharides called sialic acids. NTHi pathogenesis is related to its remarkably efficient uptake of trace amounts of free host N-acetylneuraminic acid (Neu5Ac, the primary sialic acid in humans) allowing “cloaking” of surface glycans of lipooligosaccharides (LOS) with this monosaccharide. This helps evasion from host immune clearance by “self-mimicry”, while facilitating colonization and biofilm formation. Since the mechanism of NTHi sialic acid uptake evolved by convergent evolution and is not selective for Neu5Ac, we propose to exploit this mimicry using another sialic acid called 2-keto-3-deoxy-D-glycero-D-galacto-nononic acid (Kdn). While NTHi growth was unaffected by Kdn in media, we found glycosidically-bound Kdn in LOS, which made NTHi sensitive to human sera and whole blood killing. The role of sialylation in vivo was further explored using a novel mouse model, with a human-like sialic acid profile. This mouse showed better acute NTHi colonization of the respiratory tract following intranasal challenge compared to wild type mice. Since Kdn is a metabolic byproduct in humans and should be non-toxic, the possibility of using Kdn as a safe intervention against NTHi colonization and subsequent infection is currently being explored using this mouse model.
Probiotic exopolysaccharide protects mice from acute Staphylococcus aureus bloodstream infection, reducing bacterial burden and limiting inflammation
Authors: Paik Wonbeom , Alonzo Francis , Knight Katherine L 
Published: January 2023

Abstract
Staphylococcus aureus causes severe systemic infection with high mortality. We previously showed that the probiotic Bacillus subtilis, produces an exopolysaccharide (EPS) that induces anti-inflammatory M2 macrophages. We used a lethal S. aureus bloodstream infection model, and found that mice treated with EPS prior to infection survived, and had reduced bacterial burden in the liver and spleen, as well as reduced levels of inflammatory cytokines. We showed that the EPS-induced M2 macrophages inhibited the growth of S. aureus in vitro, and by using an inhibitor of reactive oxygen species (ROS), we found that the growth inhibition of S. aureus was mediated by ROS, an M1-like property. However, these macrophages retained the M2-like capacity to inhibit proinflammatory activation of T cells by S. aureus superantigen. To test if the reduction in proinflammatory cytokines in EPS-treated mice during infection is due to anti-inflammatory effects of EPS rather than to the reduced bacterial load, we isolated splenocytes from EPS-treated mice and stimulated them with S. aureus ex vivo. We found that levels of IFN-γ, KC, and IL-6 were decreased, whereas the production of IL-10 was increased, indicating that the decrease in inflammation by EPS is not solely due to reduction in bacterial load. We suggest that the EPS-induced M2 macrophages represent “hybrid” macrophages capable of both M1- and M2-like functions and could be used to protect hosts from lethal S. aureus infection by bolstering anti-bacterial immunity, while simultaneously limiting inflammation.
Adhesion requirements of methicillin-resistant Staphylococcus aureus in bacterial pneumonia and influenza super-infection
Authors: Grousd Jennifer A , Richardson Anthony , Cooper Vaughn , Alcorn John F 
Published: January 2023

Abstract
In the respiratory tract, Staphylococcus aureus is associated with infections ranging from asymptomatic colonization to severe necrotizing pneumonia. While staphylococcal pneumonia has always been highly associated with influenza infections in young children and the elderly, it has emerged as the major cause of pneumonia associated with influenza since the 2009 H1N1 pandemic. Despite the clinical relevance of methicillin-resistant S. aureus (MRSA), few studies have examined bacterial factors of MRSA in pneumonia and how preceding influenza may alter the behavior of MRSA in the lung. Successful establishment of infection by bacterial pathogens requires adhesion to host cells. Staphylococcal species express a broad range of surface proteins that are involved in adhesion to host cells, known as the MSCRAMM family. MSCRAMM proteins have known roles in upper respiratory tract colonization, however their role in the lung is unknown. Preliminary data suggest that the MSCRAMM family members are important within the lung as MRSA lacking all MSCRAMMs (ΔsrtA) has decreased immune infiltrate in influenza super-infection. Additionally, the MSCRAMM family member SdrD has a role in both bacterial adherence as well as epithelial integrity and immunity in MRSA pneumonia and super-infection. Mice infected with MRSA lacking SdrD (ΔsdrD) have lower bacterial burden and increased expression of epithelial antimicrobial peptides cathelicidin and Reg3g with no difference in overall inflammation measured by immune infiltrate and pro-inflammatory cytokine levels. This suggests that MSCRAMM family members play a role in infection within the lung in both MRSA pneumonia and super-infection and can alter the immune response.
ANTI-ASIALO GM1 TREATMENT DURING SECONDARY TOXOPLASMA GONDII INFECTION IS LETHAL AND DEPLETES T CELLS
Authors: Denton Stephen L , Ivanova Daria L , Gigley Jason P. 
Published: January 2023

Abstract
Anti-NK1.1 and anti-Asialo GM1 (ASGM1) antibodies are used to deplete NK cells. Many antibody depletion strategies in vivo can have off-target effects. In a vaccine challenge model of T. gondii infection, we observed treatment of mice with these antibodies resulted in different survival outcomes after lethal secondary infection. Anti-ASGM1 resulted in 100% death and greater parasite burden at the site of infection than anti-NK1.1 treatment. We also found that anti-ASGM1 treatment depleted T cells. While both CD8+ and CD4+ T cells were affected, CD8+ T cells were more susceptible to the anti-ASGM1 treatment. Surface ASGM1 of the T cells was expressed on a higher percentage of CD8+ T cells than CD4+ T cells. Not all CD8+ T cells expressed ASGM1. In immunized mice ASGM1 was highly enriched on the surface of effector memory (Tem) and central memory (Tcm) CD8+ T cells, with a greater effect on Tem cells. After secondary parasite challenge, Tem, Tcm, effector (Tef) and naïve (Tn) CD8+ T cells were positive for ASGM1. Anti-ASGM1 treatment during rechallenge resulted in greater depletion of activated IFNγ+, Granzyme B+, Tem and Tef than Tcm and Tn CD8+ T cells. In addition, anti-ASGM1 depleted IFNγ+ CD4+ T cells. Recombinant IFNγ supplementation prolonged the survival of anti-ASGM1 treated mice, demonstrating that anti-ASGM1 eliminated IFNγ-producing T and NK cells important for control of the parasite. Our results thus highlight that anti-ASGM1 is not an optimal choice for targeting only NK cells and more precise approaches should be used to target them. This study also uncovers ASGM1 as a marker of activated effector T cells and the potential importance of changes in sialylation in lipid rafts for T cell activation during T. gondii infection.
Arginine-polyamine biosynthesis pathway and mediate bacillary survival in macrophages
Authors: Rameshwaram Nagender Rao , Singh Parul , Mukhopadhyay Sangita 
Published: January 2023

Abstract
Macrophages play a major role in the immune system, both as antimicrobial effector cells and as immunoregulatory cells, which induce, suppress or modulate adaptive immune responses. These key aspects of macrophage biology are fundamentally driven by the phenotype of macrophage that is prevalent in an evolving or ongoing immune response. One of the PE family proteins, PE11 (LipX or Rv1169c), demonstrate esterase activity and specific to pathogenic mycobacteria is found to polarize the macrophage towards M2 phenotype. In this study, we report that in macrophages, Msmeg-PE11 down-regulates inducible NO synthase (iNOS) and antimicrobial NO production, but in parallel there is an induction of arginase-I via p38 MAPK activation, and of ornithine decarboxylase (ODC), the first and rate-limiting step in the polyamine synthesis. Furthermore, results revealed that arginase-I regulates Msmeg-PE11 growth directly by affecting the polyamine synthesis in macrophages. These results identify a novel mechanism of immune dysregulation induced by M. tuberculosis lipolytic enzyme PE11 and by targeting PE11 and/or host arginine-polyamine biosynthesis pathway with specific inhibitors could negatively affect M. tuberculosis growth and have a positive impact in the treatment of multi-drug resistant tuberculosis.
Polyfunctional CD4+ T cells specific for Trypanosoma cruzi can be restored after in vitro treatment with IL-7 and IL-27
Authors: Natale Maria Ailen , Minning Todd , Alvarez Maria Gabriela , Lococo Bruno , Albareda Maria Cecilia , Bertocchi Graciela , Tarleton Rick , Laucella Susana 
Published: January 2023

Abstract
Chronically Trypanosoma cruzi-infected subjects bear several features associated with immune exhaustion, including an impairment in the polyfunctionality of T cells over time and alterations in the IL-7/IL-7R and IL-27/IL-27R axis. Since IL-7 and IL-27 have several functions on different immune cells, gene expression analysis was conducted in total PBMCs in response to rhIL-7 and rhIL-27 in vitro. TBX21, EOMES, GZMB and MIG-cytokine-induced gene expression was low in patients with severe Chagas disease compared with those without cardiac involvement. IL-7-induced TBX21 expression positively correlated with the magnitude of T. cruzi-specific T-cell responses. We also assessed whether treatment of PBMCs of chronically T. cruzi infected subjects with IL-7/IL-27 could improve the quality of T. cruzi-specific T-cell responses. Polyfunctionality of CD4+ T cells was improved after treatment with IL-7 and IL-27, by increasing the production of IL-2 on CD4+ T cells producing two or three functions in response to T. cruzi antigens in patients with mild cardiac disease. These findings support that alterations in IL-7/IL-27 pathways in chronic Chagas disease are not only at the signal-transduction level but also at the transcriptional regulation level. In vitro treatment of PBMCs of patients in early clinical stages of chronic Chagas disease can restore T-cell function.