bluuebunny/crossref_metadata_2025_split huggingface dataset:
Unravelling CD4 T cell Dysfunction During Chronic Infection (39.17)
Authors: Crawford Alison , Wherry E John 
Published: January 2023

Abstract
Chronic infections are a major cause of mortality and morbidity worldwide and are often associated with CD8 T cell exhaustion. T cell dysfunction in these settings is likely a major reason for failed control of infection. In many chronic infections, CD4 T cells are also of major importance (e.g., HIV, HCV and LCMV). Compared to CD8 T cells, however, there is relatively little information on dysfunction of virus-specific CD4 T cell responses. This prompted us to ask whether CD4 T cells also become dysfunctional and how the differentiation of virus-specific CD4 T cells during chronic viral infection compares to CD8 T cells. We have defined the pattern of differentiation, hierarchy of dysfunction and diversity of costimulatory and inhibitory pathways involved in CD4 T cells exhaustion by comparing responses during acute and chronic LCMV infection. The results show that while CD4 T cells do become exhausted, they do not follow the exhaustive profile that has been established for CD8 T cells. While CD4 T cells do upregulate multiple inhibitory receptors during chronic infection, the inhibitory receptors they upregulate and their expression profile differs from CD8 T cells. These studies highlight that the well-characterized phenotype of CD8 T cell exhaustion cannot be broadly applied to CD4 T cells and suggests that CD4 and CD8 T cells may require different therapeutic treatments to rescue exhaustion.
Quantifying the magnitude of antigen-specific CD4 T cell responses (39.27)
Authors: McDermott Daniel , Varga Steven 
Published: January 2023

Abstract
CD4 T cells play a vital role in orchestrating adaptive immune responses. Measuring the magnitude of the CD4 T cell response to a given pathogen is currently hindered by the lack of complete knowledge of all of the CD4 T cell epitopes. In cases where most or all of the CD4 T cell epitopes have been mapped, current estimates based on intracellular cytokine production for cytokines such as IFN-γ may also under-represent the frequency of antigen-specific CD4 T cells because of the high heterogeneity in cytokine production exhibited by differentiated effector CD4 T cells. Here we show that following lymphocytic choriomeningitis virus (LCMV) infection, T cell receptor-transgenic CD4 T cells specific to LCMV upregulate CD11a and CD49d and that expression of these adhesion molecules remains stable into memory. Expression of these integrins requires cognate antigen and is not modulated non-specifically by inflammatory signals such as stimulation with LPS or CPG. Additionally, CD11a and CD49d expression is upregulated on endogenous CD4 T cells following acute LCMV infection as well as all LCMV-specific CD4 T cells that respond to previously identified CD4 T cell epitopes. Using these markers we estimate the total magnitude of the virus-specific CD4 T cell response to multiple pathogens and our results indicate that the CD4 T cell response is substantially larger than previously thought.
Development of CD8 T-memory inflation after cytomegalovirus infection determined by initial viral burden (39.28)
Authors: Kincaid Michelle , Thomas Alicia , Zimmerman Peter , Klenerman Paul , Bergdall Valerie , Hickman-Davis Judy , Trgovcich Joanne , Cook Charles 
Published: January 2023

Abstract
Both mice and humans can develop large “inflated” populations of CD8 effector memory T-cells after cytomegalovirus (CMV) infection, and such memory inflation has been associated with immune senescence. Not all humans develop CD8 memory inflation after CMV infection, so we hypothesized that memory inflation might be predicated by the initial viral burden. Because it is impossible to know an individuals CMV inoculum during natural infection, we infected mice with murine CMV (MCMV) titers ranging from 102 to 106 PFU. After infection, peripheral blood was evaluated monthly for MCMV-specific CD8 T-cells and antibody. Using MCMV-specific MHC class I tetramers we confirm that high titer infections induce inflationary T-memory responses. In contrast, low titer infections induce significantly less inflation over time. Serum ELISA for MCMV-antibody responses showed a similar pattern. DNA from lung tissues evaluated 16 weeks after infection confirmed successful infection in all mice. Quantitative PCR showed that latent viral load in lungs correlated well with eventual lung resident T-memory responses (R2=0.96). We therefore conclude that an individual’s initial infectious burden determines their latent viral load and eventual development of memory inflation after cytomegalovirus infection, possibly explaining the wide variability in T-cell responses to CMV observed in humans.
Differential gene expression patterns associated with disease resistance in the MAIDS model (39.29)
Authors: Bakkour Sonia , Kolhatkar Nikita , Karki Sophiya , Herman Nicole , Ursu Oana , Raghavan Vidya , Stranford Sharon 
Published: January 2023

Abstract
Infection of susceptible strains of mice such as C57BL/6 (B6) with the LP-BM5 isolate of murine leukemia virus (MuLV) leads to an immunodeficiency syndrome similar to HIV-induced AIDS, known as MAIDS. However, other MAIDS-resistant strains such as BALB/c develop protective immunity against the virus after infection. Recently, we used DNA microarray analysis to compare lymphoid organ gene expression in these two mouse strains during the first week post infection. We identified a specific set of proteases and certain chemokines that are highly differentially expressed in BALB/c versus B6 mice after infection. This suggested to us that early changes in lymphoid organ architecture and/or cellular recruitment might help shape the early immune response to the virus. In follow-up experiments using real-time PCR and protein-based assays, we now show that neither protease expression nor lymphatic vascular architecture changes appear to be specifically associated with resistance to MAIDS. This despite the fact that these animals very rapidly control the viral load, showing significantly reduced viremia by five days after infection. In B6 mice, the viral load exponentially rises over the same time-course, with strongly divergent patterns apparent by day 5. We do find that certain chemokines are upregulated in the MAIDS-resistant mice at approximately one week after infection. These findings suggest that differences in cell trafficking might influence disease in this AIDS model system.
MyD88 expressing T cells are required for neuropathogenesis of Tacaribe virus. (39.6)
Authors: Tami Cecilia , Pedras-Vasconcelos Joao , Puig Montserrat , Wang Vivian , Butts Cherie , Verthelyi Daniela 
Published: January 2023

Abstract
Immune responses play a key role in the pathogenesis of viral encephalitis. Infection of neonatal C57Bl/6 (B6) mice with neurotropic arenavirus Tacaribe (TCRV) results in encephalitis, paralysis and death within 15 days of challenge. Analysis of the expression of 96 immune related genes using a mouse Taqman Low Density Array (TLDA) showed a strong inflammatory response in the brain characterized by high levels of inflammatory chemokines, mainly CXCL10/IP-10, IL1β, Granzyme, IFNγ and TNFα and T cell infiltration. In contrast, CD3ϵ-/- mice which lack T cells (CD3ϵKO) show 100% survival and minimal inflammatory response despite having similar viral loads in the brain. Transfer of either CD4+ or CD8+ T cells from B6 to CD3ϵKO mice resulted in encephalitis and death. Disease was independent of TLR2, 3, 7 or 9, whereas 90% of MyD88-/- mice survived challenge. Brains of MyD88-/- mice showed minimal inflammation and T cell infiltration but had reduced viral titers when compared to B6 or CD3ϵKO mice. MYD88 does not directly affect TCRV replication since infection of B6 and MYD88-/- primary neuro cultures in vitro rendered similar virus titers. However, T cells from MyD88-/- mice were unable to mediate encephalitis when transferred to infected CD3ϵKO. These data show that T cells mediate disease and death in TCRV infected neonates without affecting viral replication and brain tropism and suggest a critical role of MYD88 expression on T cell in the pathology.
Improved T cell restoration by depletion of T regulatory (Treg) cells followed by PD-1 blockade during chronic infection (39.9)
Authors: Penaloza-MacMaster Pablo , Araki Koichi , Ahmed Rafi , West Erin , Freeman Gordon , Rudenski Alexander , Tan Wendy , Jin H. , Aubert Rachael , Omara Leigh , Iyer Smita 
Published: January 2023

Abstract
It remains unclear if chronic infection, and the resulting antigen-specific T cell exhaustion, is a process facilitated by Tregs, cells that are known to prevent autoimmunity and maintain self-tolerance. In a model of chronic lymphocytic choriomeningitis virus (LCMV) infection, we show that depletion of CD4 cells, or specific Treg depletion (in the FoxP3 DTR mouse model), followed by PD-1 blockade results in marked increase of T cell restoration, and enhanced reduction of viral loads compared to mice that received the PD-1 blockade regimen alone. Moreover, in the FoxP3/DTR mouse model, specific depletion of Tregs alone without any further treatment results in dramatic T cell restoration (increased numbers and cytokine expression), which was greater than PD-1 blockade alone. In addition, Treg depletion alone also resulted in re-expression of CD127, and PD-1 downregulation on antigen-specific T cells. These results suggest that brief manipulation of Treg function with or without PD-1 blockade may resuscitate exhausted CD8 T cells during many established chronic infections. Our data also demonstrate an unexpectedly dominant, suppressive role of Tregs during chronic infections, and identify these cells as potential targets for vaccines and prophylactic regimens.
Prolonged Salmonella persistence occurs in the Mesenteric Lymph Nodes of antibiotic treated mice. (40.15)
Authors: Griffin Amanda , McSorley Stephen 
Published: January 2023

Abstract
We have examined a new mouse model where virulent Salmonella infection can be treated using antibiotics. Despite the apparent rapid resolution of infection, withdrawal of antibiotics before 35 days causes recurrent infection. Antibiotic-treated mice resume bacterial shedding, bacteria can be detected in the spleen and liver, and mice eventually suffer fatal recurrent infection. Although the persistent bacteria are undetectable by conventional plating methods, we were able to detect bacterial persistence in the mesenteric lymph nodes (MLN) using a Salmonella-luciferase imaging approach in all tissues of infected mice. Whole organ broth cultures confirmed MLN localization and allowed an estimation of bacterial loads in the tissue. We are currently identifying the specific cell population that harbors these bacteria in infected MLNs. Together, these data demonstrate that Salmonella can evade antibiotic killing via long-term residence in the MLN.
Removal of Toxoplasma gondii cysts from the brain by perforin-mediated activity of CD8+ T cells (40.16)
Authors: Suzuki Yasuhiro , Wang Xisheng , Jortner Benard , Payne Laura , Ni Yanyan , Michie Sara , Xu Baohui , Kudo Tomoya , Perkins Sara 
Published: January 2023

Abstract
Chronic infection with Toxoplasma gondii is one of the most common parasitic infections in humans. Formation of tissue cysts is the basis of persistence of the parasite in infected hosts and this cyst stage has generally been regarded as untouchable. Here we provide the first evidence that the immune system can eliminate T. gondii cysts from the brains of infected hosts when immune T cells are transferred into infected immunodeficient animals that have already developed large numbers of the cysts. This T cell-mediated immune process was associated with accumulation of microglia and macrophages around tissue cysts. CD8+ immune T cells possess a potent activity to remove the cysts. The initiation of this process by CD8+ T cells does not require their production of IFN-γ, the major mediator to prevent proliferation of tachyzoites during acute infection, but does require perforin. These results suggest that CD8+ T cells induce elimination of T. gondii cysts through their perforin-mediated cytotoxic activity. Our findings provide a new mechanism of the immune system to fight against chronic infection with T. gondii and suggest a possibility of developing a novel vaccine to eliminate cysts from patients with chronic infection and to prevent the establishment of chronic infection after a newly acquired infection.
Constructing epitope specific MHC-II tetramers for visualization of CD4 T cells in gram negative bacteria infections (40.18)
Authors: Li Lin-Xi , Lee Seung-Joo , McLachlan James , Moon James , McSorley Stephen 
Published: January 2023

Abstract
MHC class II peptide tetramers can be used to evaluate antigen-specific CD4 T cell responses in models of infectious disease. Here we describe the construction and functional test of epitope specific MHC-II tetramers for use in Salmonella and Chlamydia infection models. Epitope peptide sequences were covalently linked to N-terminal of I-Ab β chain, which also had his-tag for purification, and E.coli BirA signal sequence was attached to C-terminal of I-Ab α chain, which allows for site-specific biotinylation and subsequent tetramerization with fluorochrome-labeled streptavidin. I-Ab α and β chains were co-expressed in Drosophila S2 cells. pMHCII monomers were purified from culture supernatant using a Nickel-charged affinity column, and purified monomer was tetramerized using fluorochrome-labled streptavidin. Functional test of these tetramers was performed by staining peripheral lymph node cells from mice that were immunized with peptide or using spleen cells from infected mice. Therefore, antigen-specific CD4 T cell responses can be efficiently visualized by these epitope-specific MHCII tetramers during Gram Negative bacteria infection.
OX40L mediates susceptibility to chronic Leishmania donovani infection (40.26)
Authors: Snider Heidi , Reville Patrick , Sharpe Arlene , Satoskar Abhay 
Published: January 2023

Abstract
OX40 is an antigen-specific T cell cosimulatory molecule belonging to the TNF receptor superfamily that is involved in both inflammatory and autoimmune responses. Its ligand, OX40L, is primarily expressed on antigen-presenting cells. The role of OX40-OX40L interactions during visceral leishmaniasis (VL) is currently unclear. Previous studies have reported that OX40-OX40L interactions contribute to increased parasite burdens and pathology of cutaneous leishmanias caused by L. major by increasing Th2 cytokine responses. However, numerous studies have found that during VL, mixed Th1/Th2 cytokine responses are key to disease resolution. In fact, one study has shown that OX40 agonist, in conjunction with anti-CTLA-4 treatment, enhances granuloma formation and parasite clearance during VL. In this study, we examined disease outcome in OX40L-deficient C57BL/6 mice infected with VL caused by L. donovani. We found that while these mice had similar parasite burdens in their livers and spleens early post-infection, they exhibited accelerated parasite clearance during late, chronic stages of disease. Ex vivo antigen stimulation of splenocytes showed that this rapid drop in parasite levels was associated with increased IFNγ production. We therefore propose that OX40-OX40L interactions play a role in the development and pathogenesis of chronic disease caused by visceral leishmaniasis, and their blockade may represent a viable therapeutic target during clinical disease.
PD-L1 is required for optimal protective immunity to Salmonella infection (40.8)
Authors: Lee Seung-Joo , McSorley Stephen 
Published: January 2023

Abstract
Robust antibody and CD4 T cell responses are required for protective immunity against Salmonella infection. Here we examined the role of programmed death ligand 1 (PD-L1) in resolution of primary Salmonella infection. Infected PD-L1-deficient mice had higher bacterial burdens in the spleen and liver at day 21 and day 35 compared to wild-type mice indicating that PD-L1 is required for optimal protective immunity to Salmonella. Although Salmonella specific IgM and IgG2a Ab responses were similar between PD-L1-deificent and wild-type mice, PD-L1-deficient mice displayed a deficiency in CD4 T cells. Specifically, infected PD-L1-deficient mice had a significantly lower percentage of IFNγ-, and TNF-producing CD4 T cells and expressed lower levels of T-bet than wild-type CD4 T cells. These data demonstrate that PD-L1 expression is required for the generation of effective Th1 responses to Salmonella and optimal protective immunity.
Comparison of the use of role-play in both large and small classes to teach the basic concepts of an immune response to undergraduate students (41.3)
Authors: Elliott Samantha 
Published: January 2023

Abstract
Active learning exercises are touted as superior teaching strategies, yet little work has been done to truly evaluate their effectiveness in the science classroom. Role-play is considered an especially strong tool to model concepts and show relationships between entities. The immune response is a particularly difficult topic for students to grasp, due to the myriad of cellular and protein interactions involved. This study looks at the use of role-play as a tool to teach the immune response to undergraduates in both small classes, where all students participate, and large classes where only a subset of students act for their peers. Learning was measured using a standard pre- and post-test format of multiple choice questions, and student perceptions of learning were collected using an anonymous written survey. No significant differences were found in overall learning based upon class size. Role-play participation did not have a significant impact on learning compared to students who did not participate in large classes. No significant differences were seen in learning based upon student learning styles. A full analysis of the efficacy of role-play as a replacement for or an addition to lecture will be presented. This research gives insight into the efficacy of role-play as a learning tool for teaching basic concepts in immunology.
Interleukin (IL)-21, but not IL-2, induces antiviral activity and costimulatory molecules in CD8 T cells without promoting HIV replication (42.15)
Authors: Parmigiani Anita , Pallin Maria , Lichtenheld Mathias , Pahwa Savita 
Published: January 2023

Abstract
Background: Chronic HIV infection is marked by defective cytotoxic T cell (CTL) effector function, skewed terminally-differentiated profile, and reduced expression of the costimulatory molecules CD27 and CD28. Incubation ex vivo of CTL from HIV infected persons with IL-21 augments cytotoxic effector molecules and function. In this study we analyzed IL-21 effects on CTL as compared to IL-2. Methods: Purified CD8 T cells from healthy donors were pre-activated with αCD3+αCD28 and cultured with IL-21 or IL-2 for 6 days. Phenotype and effector function were evaluated by flow cytometry, gene expression by real-time PCR, effect on HIV replication with the reporter cell line TZM-bl. Results: IL-21 induced higher CTL degranulation in response to TCR stimulation, as compared to IL-2. Co-culture of IL-21-treated CTL with autologous HIV infected CD4 T cells reduced HIV replication. Importantly, IL-21 did not induce viral replication when added to HIV infected CD4 T cells. Furthermore, TCR-activated CTL upreglated CD27 and CD28 and acquired a central memory phenotype when incubated with IL-21, but not with IL-2. IL-21 also selectively induced Bcl6, key transcription factor for memory T cells. Conclusions: Since IL-21 enhances CTL antiviral activity, promotes a central memory phenotype and induces costimulatory molecules, this cytokine has an appealing immunomodulatory profile and merits further consideration for cytokine-based therapies, alone or in combination with antiretroviral drugs.
Non-hematopoietic IL12p40-responsiveness is required for tubercular granuloma formation. (42.19)
Authors: Robinson Richard , Cooper Andrea 
Published: January 2023

Abstract
Genetic studies have repeatedly demonstrated that the control of mycobacterial infections, including M. tuberculosis, is tightly coupled with IL12Rβ1-dependent signaling. The explanation historically given for this close association is that IL12p40-dependent cytokines (e.g. IL12p70) are required to generate protective, IFNγ-producing T cells and NK cells; in the absence of IL12Rβ1, these IFNγ-producing cells fail to develop and M. tuberculosis grows unchecked. Here, we present data that suggest an alternative explanation for the association between IL12Rβ1-deficiency and mycobacterial susceptibility. Using a mouse model of tuberculosis we show that in addition to influencing hematopoietic cells, CD11c+-derived IL12p40 also acts on non-hematopoietic cells though IL12Rβ1 to control M. tuberculosis growth. Further examination demonstrated that while mice with il12rb1-deficient stroma accumulate numerous immune cell subsets in the lung following infection, these cells fail to properly organize into protective tubercular granulomas. Granuloma formation was not dependent on IL12Rβ2 or IL23, suggesting that either IL12p40 monomer or IL12(p40)2 was responsible for this effect. Thus, while the absence of hematopoietic IL12Rβ1 does compromise the ability of mice to control M. tuberculosis infection, our data suggests that the influence of IL12p40 on non-hematopoietic cells is equally important.
Interferon-γ controls Th17-mediated immunopathology during mouse hepatitis virus infection (42.2)
Authors: Qin Zhihai 
Published: January 2023

Abstract
Due to its lethality, fulminant hepatitis, the most severe form of viral infection in liver, is a global health concern. Here we examine the function of Th17 cells during the mouse hepatitis virus (MHV) induced hepatitis. We find that IL17 levels in serum are rapidly upregulated and positively correlated to liver damage and death of mice upon viral infection. The unresponsiveness of host cells to IFNγ significantly enhances virus-induced Th17 response. Unrestricted IL17 production accounts for severe liver damage as well as detrimental inflammation in infected IFNγ receptor deficient (IFNγR-/-) mice, since neutralization of IL17 effectively suppresses inflammation and protects mice from liver injury. IFNγ facilitates antigen-induced apoptosis of Th17 cells in vitro and adoptive transfer of IFNγR deficient, but not IFNγR competent CD4+ T cells leads to enhanced liver damage in wild-type mice. The results demonstrate an essential role of Th17 cells in MHV-induced immunopathology and indicate the importance of IFNγ in maintaining immune balance between Th1 and Th17 responses during the acute viral infection.