bluuebunny/crossref_metadata_2025_split huggingface dataset:
Monocytes express the serine protease granzyme B - potential involvement in antigen processing and presentation. (P5033)
Authors: Schuldhaus Christopher , Beyer Thamara , Kaltenmeier Christof , Lindner Stefanie , Schrezenmeier Hubert , Jahrsdörfer Bernd 
Published: January 2023

Abstract
In recent years, dendritic cells derived from monocytes (mo-DC) have been extensively studied as novel cell-therapeutic candidates for the treatment of various tumors. In order to elicit tumor-specific CTL responses, DC need to be capable of cross-presenting antigens. Recently, the serine protease granzyme B (GrB) was found to be crucially involved in cleavage and cross-presentation of antigens. We therefore hypothesized that monocytes may be able to express GrB under certain circumstances, comparable to other DC precursors including mDC and pDC. Using various methods including FACS analysis, ELISpot and Western immunoblot we found that monocytes can express GrB depending on various external stimuli. Importantly, we found that the TLR4 ligand LPS appears to play a central role in the induction of GrB in monocytes, and that the presence of antigen-stimulated B cells synergistically enhances GrB expression in monocytes. Moreover, when maturing monocytes into mo-DC, the IL-2 family cytokine IL-7 further supported the expression of GrB in the emerging mo-DC population. This is the first report describing the expression of GrB protein in monocytes and mo-DC in response to various cytokine and TLR stimuli. Our results may open novel approaches to the improvement of mo-DC-related cellular vaccines based on the expression of certain proteases such as GrB.
Understanding MHCII-restricted T cell receptor cross-reactivity to foreign peptides (P5011)
Authors: Nelson Ryan , Beisang Dan , Taylor Justin , Jenkins Marc 
Published: January 2023

Abstract
CD4+ T cells bearing unique T cell receptors (TCRs) recognize antigens in the form of peptides bound to major histocompatibility complex class II proteins (p:MHCII). In mice, structural studies of peptides bound to the MHCII molecule I-Ab have revealed that p:I-Ab complexes consist of a core peptide of at least 9 amino acids. Five of the positions within the nonamer core interact with the peptide binding groove of I-Ab and orient the 4 TCR contact amino acids so that they are accessible for TCR recognition. However, the rules that govern this TCR recognition and cross-reactivity for p:MHCII complexes are largely unknown. Using a p:MHCII-tetramer based approach, we tested the limits of MHCII-restricted TCR cross-reactivity by studying two nonamer peptides with 4 identical TCR contact amino acids but different I-Ab anchor residues. To our surprise, we found that 80% of T cell clones could not discriminate between the two peptides. When we expressed one of the peptides as a self peptide in a transgenic mouse model, we found that the T cell response to immunization with the other peptide was decreased by over 50%. These results could explain how TCR cross-reactivity can account for repertoire selection as well as autoimmunity induced by molecular mimicry.
HLA-F and MHC-I open conformers cooperate in an MHC-I antigen cross presentation pathway. (P5015)
Authors: Geraghty Daniel , Goodridge Jodie , Lee Ni , Burian Aura , Pyo Chul-woo , Tykodi Scott , Warren Edus , Yee Cassian , Riddell Stanley 
Published: January 2023

Abstract
Peptides that are presented by MHC class I (MHC-I) are processed from two potential sources - newly synthesized endogenous proteins for direct presentation on the surface of most nucleated cells and exogenous proteins for cross-presentation typically by professional antigen presenting cells. Here we present data that implicates the non-classical HLA-F and open conformers of MHC-I expressed on activated cells in a pathway for the presentation of exogenous proteins by MHC-I. This pathway is distinguished from the conventional endogenous pathway by its independence from TAP and Tapasin and its sensitivity to inhibitors of lysosomal enzymes, and further distinguished by its dependence on MHC-I allotype-specific epitope recognition for antigen uptake. Thus, our data from in vitro experiments collectively support a previously unrecognized model of antigen cross-presentation mediated by HLA-F and MHC-I open conformers on activated lymphocytes and monocytes, which may significantly contribute to the regulation of immune system functions and the immune defense.
HIV-1 envelope glycoprotein variable loop 4 and 5 are indispensable for envelope structural integrity (P5017)
Authors: Tingting Yuan , Zhang Mei-Yun , Li JingJing 
Published: January 2023

Abstract
HIV-1 envelope glycoprotein (Env) is a trimer of non-covalently linked heterodimer of gp120 and gp41 subunits. Gp120 is composed of five conserved regions (C1-5) that are interspersed with 5 variable regions (V1-5). Despite less conserved nature of the sequences, variable loops may be functionally important for virus entry and constitute neutralization determinants. To investigate the importance of loops for Env biology, we generated a series of loop deletion mutants and investigated the effect of each loop deletion on Env structural integrity, and on Env expression, cell surface display, virus packaging and entry into permissive cells. We found that loop V4 and V5 were important for envelope structural integrity. Replacement of V4 or V5 with a flexible linker led to loss of the binding of CD4 binding site antibodies and CD4-induced antibodies to the Env, but enhanced the exposure of the membrane-proximal external region. Although replacement of V4 or V5 with the flexible linker did not affect Env expression in cells, it significantly affected Env display on cell surface, leading to the failure in virus packaging and subsequent entry into permissive cells. HIV-1 Env variable loop V4 and V5 are indispensable for Env structural integrity. Deletion of V4 and V5 significantly affected Env cell surface display, virus packaging and subsequent virus entry into the cells.
Low GILT expression is associated with poor survival in diffuse large B cell lymphoma (P5057)
Authors: Phipps-Yonas Hannah , Cui Haiyan , Haddock Ellen , Deymier Martin , Lybarger Lonnie , Roe Denise , Hastings Karen 
Published: January 2023

Abstract
Diffuse large B-cell lymphoma (DLBCL) is the most common form of aggressive non-Hodgkin lymphoma. Since low MHC class II expression is associated with poor survival in DLBCL, we examined whether expression of other components in the MHC class II antigen processing pathway may be important in DLBCL biology. Gamma-interferon-inducible lysosomal thiol reductase (GILT) reduces protein disulfide bonds in the endocytic compartment exposing additional epitopes for class II binding and facilitating antigen presentation. In four independent gene expression profiling cohorts with a total of 585 DLBCL patients, low GILT expression was significantly associated with poor overall survival. In contrast, low expression of MARCH1, an E3 ligase that regulates class II trafficking, and HLA-DRA, a classical MHC class II gene, were associated with poor survival in one of four cohorts. The association of low GILT expression with poor survival is independent of established clinical and molecular prognostic factors, the International Prognostic Index and cell of origin classification, respectively. GILT protein expression was detected in both tumor cells and tumor-infiltrating antigen presenting cells. These studies demonstrate that GILT expression levels correlate with clinical outcome and underscore that antigen processing is critical to patient survival in DLBCL.
Identification and functional characterization of the antigen presenting cells recognized by tumor-associated regulatory T cells in genetically engineered mouse models of prostate cancer (P5065)
Authors: Shen Lynn , Nishi Saki , Savage Peter 
Published: January 2023

Abstract
The enrichment of Foxp3+ regulatory T cells (Tregs) constitutes a central mechanism of immune regulation, but has also been associated with poor patient prognosis in a variety of human cancers. Previous studies have suggested that Treg development, specificity, and mechanism of action are dependent upon antigen recognition; however, little is known about the identity of the antigen presenting cells (APCs) that are directly recognized by Tregs in vivo. Previously, we have identified an endogenously occurring monospecific Treg population, termed “MJ23 Tregs,” that is highly enriched in the prostate tumors of TRAMP mice. Using MJ23 T cells as a probe, we have determined that despite the presence of multiple MHC class II-expressing cell types within tumor lesions, the antigen recognized by MJ23 Tregs is exclusively presented by a distinct subset of dendritic cells (DCs). In order to determine the functional significance of this interaction, ongoing work aims to determine the impact of DC ablation on Treg localization and function, and on prostate cancer development. In all, our work will determine the extent to which the activity of Tregs within tumor lesions is coordinated in trans by the APC.
Transcriptional and functional conservation between human Langerhans cells and mouse thymic DCs (P5067)
Authors: Klechevsky Eynav , Artyomov Maxim , Munk Adiel , Cella Marina , Tung Thomas , Lam Samuel , Schreiber Robert , Klechevsky Eynav 
Published: January 2023

Abstract
The characterization of human DC subsets is essential for the design of new vaccines and for better translation of mouse immunological data to the clinic. Previously, we showed that human epidermal Langerhans cells (LCs) were highly efficient at priming effector CD8+ T cell responses. However, the ability of mouse LCs to cross-present antigens and drive potent CTL responses is controversial. We used expression profiling to find the human LC equivalent in the mouse. Our studies suggest that the mouse equivalent to the human LC are the two mouse thymic DC subsets. Our studies also reveal a distinct genetic signature of over 25 genes, that could identify and predict which DC subsets can cross-present. The cross-presentation signature was present in the human blood CD141+ DCs and correctly identified the ability of other distinct human and mouse DC subsets to cross present. We confirmed these predictions with the functional ability of DCs to efficiently induce antigen-specific effector CD8+ T cells. Our studies may help bridge differences between mouse and human DCs and facilitate the application of these data to the clinic.
Intracellular detection of antibody-bound viruses and bacteria by TRIM21 (P4159)
Authors: McEwan William , Tam Jerry , Watkinson Ruth , Bidgood Susanna , Hauler Felix , Mallery Donna , James Leo 
Published: January 2023

Abstract
Antibodies are a key component of the adaptive immune response but their activity has previously thought to be limited to the extracellular environment. We have demonstrated that pathogens traffic surface-bound antibodies to the intracellular compartment where they are recognised and neutralized by the high affinity cytosolic Fc receptor TRIM21. In this study we demonstrate that following detection of pathogen-antibody complexes, TRIM21 is able to synthesise K63-linked ubiquitin chains resulting in signalling via NF-κB, AP-1 and IRF3/5/7 pathways. Detection by TRIM21 is sufficient to induce the production of cytokines including CXCL10, IL-6 and IFN-β. Furthermore a wide range of intracellular pathogens, including Salmonella, non-enveloped DNA viruses and RNA viruses can be detected by TRIM21. TRIM21 therefore provides context-dependent detection of intracellular antibody, mediating potent neutralization and signalling functions.
Abnormal neutrophils present in peripheral blood of Chronic Atypical Neutrophilic Dermatosis with Lipodystrophy and Elevated Temperature (CANDLE) syndrome patients. (P4173)
Authors: Biancotto Angelique , Liu Yin , Pelletier Martin , Goldbach-Mansky Raphaela , McCoy J. Philip 
Published: January 2023

Abstract
CANDLE syndrome (CS) is an autoinflammatory disease caused by autosomal recessive mutations in PSMB8. CANDLE involves dysregulation of the IFN signaling pathway and skin infiltrates of immature neutrophils and other cells. We investigated circulating neutrophils from patients with CS for changes in activation or homing markers and quantified the circulating low density granulocytes.. Compared with healthy donors (HD), or matched, paired unaffected parents (PP) carrying one copy of the mutated gene CS patients had increased proportions of immature CD10- neutrophils (7% in CS vs 2.6% in PP and vs 2.4% in HD). In addition, in CS, the reduced proportion of CD10+ mature neutrophils presented an activated phenotype based on expression of CD64 (8.6% vs 4.5% in PP vs 0.9% in HD). We illustrated changes in the maturation activation pattern of neutrophil by calculating the CD10+/CD10- ratio, and showed reduced ratio in CS patients, ratio=13.3 vs 40.1 in PP vs 44.4 in HD. We observed a reduction of CD62L and CD11b/CD18 expression on mature, and increased expression on the immature population. We observed higher circulating LDGs in PBMC fraction of CS (2%) compared to PP (1.1%) or HD (0.7%). The abnormal phenotype of circulating neutrophils, could explain the migration of immature neutrophils to inflammatory skin tissues; however, the overlap of this population with the increased circulating LDG population and their capacity to generate functional responses, remains still unclear.
Evidence for renewal and reconstitution of splenic marginal zone macrophages in young and aged mice (P4181)
Authors: Witte Pamela , Bahamon Erika , Birjandi Shirin 
Published: January 2023

Abstract
Previously, we showed that the spleens of old mice have reduced frequency of MZM and less ability to clear blood-borne particles. One reason for the demise of MZM with age may be lack of renewal, but little is known about turnover of MZM. Here, turnover of MZM was assessed after giving BrdU (injection or in drinking water). Double staining for MARCO and BrdU in spleens from young mice showed that MZM were turning over, either proliferating in situ or derived from dividing precursors. Next, flow cytometry was used to compare the frequencies of BrdU+ MZM per total MZM, from young and old mice. The frequency of BrdU+ MZM was less in aged mice, suggesting that MZM renew more slowly in old than in young. We are interested in the possibility that MZM can be re-established in the aged spleen by cell transfer. Since CCL21 is required to establish MZM, we first compared young and old splenic tissue for expression and staining patterns of CCL21. The distribution was reduced in the PALS and variable in other areas of old spleens; but, total expression was similar between young and old mice, suggesting that sufficient CCL21 may be available in old spleens. We then asked if young bone marrow cells, transferred to intact old mice, could reconstitute MZM in the spleens of old mice. BrdU-labeled young bone marrow cells were used for transfer. The results showed evidence that a low frequency of MZM, derived from young marrow, could establish in intact old mice.
Selenoprotein K interacts with ASAP2 in macrophages to promote phagocytosis (P4151)
Authors: Norton Robert , Huang Zhi , Fay Jeffrey , Hoffmann Fukun , Hoffmann Peter 
Published: January 2023

Abstract
Selenium is a mineral micronutrient that is essential in a variety of biological systems, including immune responses. Selenium is used for biosynthesis of the amino acid selenocysteine, which is used by selenoproteins to carry out biological functions. In humans, 25 selenoproteins have been identified and Selenoprotein K (SelK) was recently identified as an endoplasmic reticulum transmembrane protein important for calcium flux during the activation of immune cells. ASAP2 is an ARF-GAP that localizes to the phagocytic cup when a macrophage engulfs a pathogen. Implementation of the SH3 hunter software predicted that the SH3-binding domain of SelK associates with SH3 domain containing proteins. Furthermore, in an unbiased screen for SelK binding partners we found that ASAP2 immunoprecipitates with SelK. When we tested mutants of SelK with alterations in the SH3 binding domain, we discovered that this interaction was abolished. This indicates that SelK has a functional SH3 binding domain that interacts directly with ASAP2. It has also been established by our lab that SelK KO macrophages exhibit notably impaired phagocytosis of opsonized beads. Studies are underway to determine if the lack of SelK prevents ASAP2 from localizing to the phagocytic cup.
Nectin and nectin-like molecules: immune regulator, adhesion molecule and virus receptors (P1001)
Authors: Gao George 
Published: January 2023

Abstract
Nectin and nectin-like proteins are cell adhesion molecules that mediate the formation of cell adherens junctions by forming homo- or hetero-dimers. Some members of this protein family can also be used by immune receptors to mediate immune recognition. For instance, nectin-like 2 (Necl-2) is used as a ligand for the immune system by interaction with the immune receptor CRTAM (class-I MHC restricted T-cell associated molecule), which is mainly expressed on the surface of cytotoxic lymphocyte cells. However, the Necl-2/CRTAM binding mode and its relationship to cell adhesion are not known. Here, we report a Necl-2/CRTAM complex structure, demonstrating that Necl-2 binding to CRTAM competes with the dimerization of CRTAM and possibly Necl-2. Necl-2 occupies the CRTAM homodimer interface, making homodimerization impossible. Mutational and functional analyses identified key amino acids (double "lock-and-key") responsible for the binding. Our work illustrates how the cell adhesion molecule Necl-2 competitively binds the immune receptor CRTAM. Otherwise, the nectin proteins can also be employed as the virus receptors, such as herpes simplex virus and measles virus.
Regulation of TNFR:TNFRL interactions mediates CD8+ T cell clonal competiton (P1013)
Authors: Burchill Matthew , Tamburini Beth , Marrack Pippa , Kedl Ross 
Published: January 2023

Abstract
The ability to respond to self and foreign antigens requires a network of signals between antigen presenting cells (APCs) and responding T lymphocytes. In our studies, we demonstrate that access to TNF-ligands confer a competitive advantage to CD8+ T cells in response to foreign antigen. Previous work has demonstrated that immunization of mice deficient in CD27, the receptor for CD70, results in a severely restricted antigen-specific CD8 T cell repertoire. We show that adoptively transferred CD8+ T cells are able to compete against endogenous antigen-specific CD8+ T cells more effectively than CD27-deficient CD8+ T cells. To dissect the mechanism by which CD27 expression confers a competitive advantage to CD8+ T cells, we were able to demonstrate that upon engagement of CD27 by CD70, CD27 is lost from the surface of CD8+ T cells and captured by CD70 expressing dendritic cells, effectively blocking access to CD70. These data demonstrate a novel mechanism by which CD8+ T cells of the same specificity can compete against one another by regulating access to TNF-ligands on APCs. Furthermore, multiphoton microscopy revealed CD27 expression is critical to maintain stable T cell:APC interactions. Collectively, our data demonstrate that T cells compete against each other for access to the TNF-ligands, an interaction which affects the duration and potency of T cell:DC interactions and thus influences the repertoire of responding CD8+ T cells to self or foreign antigens.
GITR potentiates anti-viral T cell immunity by limiting regulatory T cells (P1015)
Authors: Clouthier Derek , Wortzman Michael , Watts Tania 
Published: January 2023

Abstract
The immune system must be tightly balanced to control infection while avoiding immune pathology. We investigated the role of the glucocorticoid-induced tumour necrosis factor receptor (GITR) during infection of mice with persistent lymphocytic choriomeningitis virus (LCMV) clone 13 infection. Infection of wild-type (WT) and GITR-/- mice with LCMV revealed that GITR plays a critical role in T cell responses and viral control. At 8 days post-infection (dpi), GITR-/- mice showed 3-fold fewer LCMV-specific CD8+ T cells, and these cells expressed significantly higher levels of inhibitory receptors Tim-3 and PD-1. These defects became more striking at 45 dpi, when there was also a substantial deficit in multifunctional (IFNγ+CD107a+TNFα+) CD8+ T cells in GITR-/- relative to WT mice. GITR-/- mice had 35-fold higher viral load in the kidney 8 dpi and 10-fold higher at day 45. Depletion of CD4+ T cells ameliorated the immune defects observed in GITR-/- mice, suggesting that a CD4+ population largely contributed to the GITR-/- phenotype. Strikingly, there were 4- to 5-fold more CD4+Foxp3+ regulatory T cells (Tregs) in the spleen and lymph nodes of GITR-/- mice 8 dpi, and only slightly more at 45 dpi. The dramatic increase in Treg numbers in GITR-/- mice 8 dpi is accompanied by a more suppressive phenotype. These studies demonstrate that GITR plays an indirect, yet critical role in CD8+ T cell responses and viral control by limiting the accumulation and function of Foxp3+ Tregs.
Irradiation at a young age induces immune-modulation through NF-κB pathway on spleen cells in old age mice (P3044)
Authors: Yoshida Yasuhiro , Song Yuan , Okazaki Ryuji 
Published: January 2023

Abstract
It is reported that irradiation induces shortened lifespan in mice with dose-dependent. We also previously reported that young-age irradiated mice induces shorten lifespan compared to non-irradiated mice. In addition, the number of lymphocytes in the S- and G2/M- phases was significantly increased in the irradiated mice. However, the detail mechanism is still not fully understood. In the present study, we demonstrated that irradiation at young age induces immune-modulation of splenocytes in old age mice. The p53+/- mice were exposed to 3 Gy at 8 weeks of whole-body irradiation and were sacrificed at about 54 weeks of age. The expression of CDK2 was increased in the splenocytes of the mice irradiated at 8 weeks. Electrophoretic mobility shift assay demonstrated increased activated-NF-κB in the splenocytes of the mice irradiated at 8 weeks but not at 17 and 30 weeks mice. Cell viability assay shows constant activation of splenocytes in the mice irradiated at 8 weeks both female and male mice compared to non-irradiated mice. In contrast to this, splenocytes of the mice irradiated at 17 and 30 weeks were similar activities to non-irradiated mice. Finally, IL-6 production from splenocytes was measured by ELISA and irradiated mice have high production of IL-6. Taken together, these results suggest that young age irradiation induced immune-modulated response in the second lymphoid organ, which may relate to be activation of NF-κB.