bluuebunny/crossref_metadata_2025_split huggingface dataset:
Investigating signaling downstream of SLAM family members CD84 and Ly108 in thymocytes and activated T cells (99.4)
Authors: Ghai Mala , Cannons Jennifer , Schwartzberg Pamela 
Published: January 2023

Abstract
The SLAM family consists of 6 immunoregulatory receptors including CD84 and Ly108. SLAM receptors are expressed on T, B, NKT cells, DCs and macrophages and are self ligands that have intracellular binding sites for the adaptor molecule SAP. SAP recruits and activates the FynT kinase, resulting in signaling leading to cytokine production, cytotoxicity, enhanced cellular interactions and thereby immune regulation. Defective SAP expression is associated with the disease XLP, characterized by dysregulated hyperimmune response to EBV infection and impaired humoral responses. Both CD84 and Ly108 are highly expressed on developing thymocytes and activated T cells, including Tfh cells, which are important for germinal center responses. We have found that CD84 affects GC formation and that CD84 and Ly108 participate in T:B cell interactions. SAP and Ly108 signaling is also implicated in development of innate T cells, like NKTs. We find that Ly108 phosphorylation varies in different genotypes of mice. While thymi of SAP-/- mice, that lack NKT cells, demonstrate reduced pLy108, thymi from Itk-/- mice that develop increased numbers of innate T cells, demonstrate increased pLy108. As development of this increased innate T cell population in Itk-/- mice requires SAP, we hypothesize that SAP-associated Ly108 may be contributing to their development. We are further characterizing biochemical and cellular properties of these receptors, given their roles in these important T cell lineages.
Dec2 promotes Th2 cell differentiation by enhancing IL-2R signaling (99.6)
Authors: Sun Bing , Liu Zhiduo 
Published: January 2023

Abstract
Helper T cell (Th cell) differentiation is precisely regulated by thousands of genes at different stages. In the present study, we demonstrate that Dec2, a transcription factor belonging to the bHLH (basic helix-loop-helix) superfamily, is progressively induced during the course of Th2 differentiation, especially at the late stage. The up-regulated Dec2 can strongly promote Th2 development under Th2-inducing conditions, as evidenced by retrovirus-mediated gene transfer or transgenic manipulation. In addition, an enhancement of Th2 responses is also detectable in Dec2 transgenic mice in vivo. Conversely, RNAi-mediated suppression of endogenous Dec2 could attenuate Th2 differentiation. Finally, we show that the enhanced Th2 development is at least in part due to substantial up-regulation of CD25 expression elicited by Dec2, thereby resulting in hyperresponsiveness to IL-2 stimulation.
Gamma-interferon-inducible lysosomal thiol reductase diminishes cathepsin S expression and function (100.27)
Authors: Phipps-Yonas Hannah , Semik Vikki , Hastings K. 
Published: January 2023

Abstract
MHC class II-restricted processing requires protein degradation in the endosomal pathway for activation of CD4+ T cells. Gamma-interferon-inducible lysosomal thiol reductase (GILT) facilitates the processing of class II-restricted antigens by reducing protein disulfide bonds. Our previous work demonstrates that reductase active site mutants of GILT have diminished processing of precursor GILT to mature GILT, suggesting that GILT’s reductase active site may decrease the expression or activity of lysosomal proteases responsible for cleavage of GILT’s N- and C-terminal pro-peptides. Cathepsin S (CatS) is capable of processing precursor GILT to its mature form and mediates essential steps in class II-restricted processing, including proteolysis of large polypeptides and invariant chain cleavage. Therefore, we sought to determine whether GILT’s reductase activity regulates CatS expression and function. Our studies show GILT and CatS colocalize within lysosomes of murine B cells. GILT expression acts post-transcriptionally to decrease CatS steady state protein expression. GILT’s reductase active site is necessary for diminished CatS protein levels. However, GILT does not substantially alter the steady state protein expression of other lysosomal proteins, H2-M, H2-O or CatL. In addition, GILT expression decreases proteolysis of a CatS-selective substrate. Thus, GILT’s reductase activity is likely to fine tune class II-restricted antigen processing through decreasing CatS activity.
Distinct spatial localization of resident dendritic cell subsets in lymph nodes (100.30)
Authors: Gerner Michael , Ifrim Ina , Kastenmuller Wolfgang , Germain Ronald 
Published: January 2023

Abstract
Dendritic cells (DCs) are essential for uptake and presentation of antigens (Ags) for T cell activation and can be divided into subsets with varying Ag-presentation capacities. It is not clear whether intrinsic differences or variation in spatial localization and preferential Ag access both contribute to differential Ag-presentation by DC subsets. We thus developed a novel approach of combining multi-parameter (6 or 7 color) confocal microscopy with analytical masking to allow direct in-situ visualization of cellular populations identified by complex phenotypic surface markers. We determined the spatial localization of major resident lymph node (LN) DC subsets and observed preferential positioning of certain populations to distinct LN zones. Some DCs physically associated with lymphatic sinuses (LS) and extended dendrites directly into the LS. While small protein Ags can be directly delivered to resident DCs via LN conduits, particulate Ags are thought to be presented via migratory DCs arriving from peripheral sites. Using 2-photon microscopy, we observed the LS-associated DCs actively sampling the LS for particulate Ags and the formation of T cell clusters in zones proximal to the LS after particulate Ag injection. These results suggest the existence of specialized micro-domains for DC subsets within LN and suggest that LS-associated DC are important for T cell activation to particulate Ags. This research was supported by the Intramural Research Program of the NIH, NIAID.
LTβR signaling in Dendritic Cells induces a Type I IFN response that is required for optimal clonal expansion of CD8+ T cells (100.40)
Authors: Ng Dennis , Summers deLuca Leslie , Gao Yunfei , Wortzman Michael , Watts Tania , Gommerman Jennifer 
Published: January 2023

Abstract
During an acute infection, dendritic cells (DC) are triggered by pattern recognition receptors (PRR) to produce inflammatory molecules that are important for the expansion and function of CD8+ T lymphocytes in order to clear the infection. In contrast, tumours or autoimmune responses against tissue antigens produce very little inflammation, yet the immune response can proceed in the absence of obvious PRR activation. In these situations, DC require CD4+ T cell help to initiate CD8+ T cell-mediated immunity. Here we generated mixed chimeric mice lacking Lymphotoxin-β receptor (LTβR) specifically on the DC, and we found that they exhibit reduced CD8+ T cell expansion in a help-dependent response. In contrast, inhibition of the CD40 signaling only impaired CD8+ T cell interferon-γ (IFN-γ) production. Furthermore, we have identified that LTβR signaling in DC triggers IFN-α/β expression in the absence of any PRR ligand and is critical for antigen specific CD8+ T cell expansion. Therefore, this study demonstrates that different TNF family members provide integrative signals that shape the licensing potential of antigen-presenting DC.
Inhibition of antigen cross-presentation by intravenous immunoglobulins (100.41)
Authors: Bazin Renée , Trepanier Patrick 
Published: January 2023

Abstract
Intravenous immunoglobulins (IVIg) are therapeutic preparations of human IgG used to treat primary and secondary immunodeficiencies. In addition, IVIg exert anti-inflammatory effects in several autoimmune disorders, and the constant increase in their use exposes providers and patients to considerable risks of shortage. Understanding their numerous and complex mechanisms of action is required to develop appropriate substitutes. Our research group recently demonstrated that IVIg inhibited the in vitro and in vivo activation of CD4 T cells following interaction with dendritic cells (DC) (Aubin et al, Blood 2010). In the present work, we investigated whether IVIg could also interfere with the activation of CD8 T cells, which contribute to the persistence and severity of certain autoimmune conditions. C57BL/6 bone marrow-derived DC were treated with IVIg and used to cross-present ovalbumin to fluorescently labelled ova-specific OT-I CD8 T cells. Cell activation was assessed by measuring T cell fluorescence distribution by flow cytometry. Results showed that IVIg-treated DC were significantly less efficient in activating CD8 T cells. The inhibition correlated with a decrease in IL-2 and IFN-y pro-inflammatory cytokine secretion. These results support a novel immunomodulatory mechanism by which IVIg decrease DC capacity to cross-present antigens to CD8 T cells. The molecular mechanisms of this inhibition and its importance in vivo are currently being investigated.
Elf3 plays a role in regulating dendritic cell maturation and function (100.42)
Authors: Kushwah Rahul , Wu Jing , Oliver Jordan , Hu Jim 
Published: January 2023

Abstract
Elf3 belongs to the family of epithelium-specific Ets transcription factors and can be upregulated in non-epithelial cells upon cytokine stimulation. Among Ets family transcription factors, Elf3 is most highly induced during inflammation, yet its function is not well understood. Here we demonstrate an important role of Elf3 in regulating dendritic cell (DC) function. Intraperitoneal injection of ovalbumin (OVA)-Alum to Elf3-/- mice resulted in increased migration of DCs to the peritoneal space along with hypermaturation followed by increase in subsequent migration of DCs to the draining lymph nodes. In vitro cultured Elf3-/- DCs underwent spontaneous maturation in absence of any inflammatory stimuli and upon exposure to inflammatory stimuli underwent hypermaturation compared to Elf3+/+ DCs, indicating a role of Elf3 in regulation DC maturation. Elf3-/- mice had normal T cell development but mounted an exaggerated Th2 response upon OVA exposure. Naïve T cells cultured with Elf3-/- DCs showed impairment in Th1 and Th17 differentiation with an increased propensity for Th2 differentiation. This was mediated by an impairment of IL-6 and IL-12 production by Elf3-/- DCs. The impairment of IL-6 and IL-12 production was due to impairment of IL-6 and IL-12p40 gene induction in Elf3-/- DCs in response to inflammatory stimuli. Impairment of Th1 differentiation promoted Th2 differentiation. Taken together, our findings identify a role of Elf3 in regulating DC maturation and function.
Identification of a novel motif important for the activity of ring-type E3 ligases using MARCH1 as a model (100.52)
Authors: Bourgeois-Daigneault Marie-Claude , Thibodeau Jacques 
Published: January 2023

Abstract
The MARCH family of proteins are RING-CH type E3 ubiquitin ligases responsible for the ubiquitination and endocytosis of cell surface proteins related to immune response. We are particularty interested in MARCH1 and 8, two members of the family that are known to downregulate the cell surface expression of MHC II, CD86 , TfR and CD95. Canonical sorting motifs in the cytoplasmic portions of murine MARCH1 and human MARCH8 were identified and reported by others to be necessary for the function. We hypothesized that such motifs in human MARCH1 are important for it’s function. Methods: We used co-immunoprecipitations and FRET to monitor interaction of MARCH1 with various proteins. Protein expression, function and localization were determined by flow cytometry, confocal microscopy and western blotting. Results: Our results showed the presence of functional sorting motifs in both N- and C-terminal cytoplasmic portions of human MARCH1. However, these signals are not essential for the activity of MARCH1. We used a series of mutants to identify functional regions on MARCH1. Our results point to a novel motif. Interestingly, that motif is found in many other proteins and appears to be important for the function of other RING-type E3 ligases. Conclusions: Our results confirmed the presence of sorting motifs in MARCH1 and highlight important species-specific functional domains. The newly identified domain of MARCH1 will shed light on the structure of RING-type E3 ubiquitin ligases.
Structural basis of HLA-DO inhibition of HLA-DM catalyzed peptide exchange on MHC class II (100.53)
Authors: Guce Abigail , Mortimer Sarah , Mellins Elizabeth , Karlsson Lars , Stern Lawrence 
Published: January 2023

Abstract
HLA-DO (DO) is a non-polymorphic, non-classical MHC class II molecule that localizes to the lysosome with HLA-DM (DM). DO is known to inhibit MHC class II peptide loading mediated by DM. The mechanism of inhibition by DO as well as the interactions between DO and DM remain unknown. Here, we present the three-dimensional structure of the DM and DO complex determined by x-ray crystallography at 3.2 Å resolution which is also the first resolved structure of DO. DO exhibits close structural similarity to the MHC class II molecule, HLA-DR (DR), with an rmsd of 0.8 Å2 despite only 25% sequence homology.The crystal complex shows DO residues mainly at the N-terminal side of the α1 peptide-binding groove interact with DM residues located at a concave surface. Some interactions are also observed involving DO residues from the IgG-like domain . DM concave surface includes an acidic patch where residues in and surrounding this acidic patch and residues in the IgG-like domain interact with DO. Interestingly, the interaction surface on DM to DO is spatially close to DM’s interaction surface for DR that was suggested by molecular modeling and mutagenesis studies. The novel structure of the DM/DO complex presented here provides an insight on the possible mechanism of inhibition of DO on DM as well as the mechanism of how DM catalyzes peptide loading to peptide free DR.
Structural basis for antigenic peptide precursor processing by the endoplasmic reticulum aminopeptidase ERAP1 (100.57)
Authors: Nguyen Tina , Chang Shih-Chung , Evnouchidou Irini , York Ian , Rock Kenneth , Goldberg Alfred , Stratikos Efstratios , Stern Lawrence 
Published: January 2023

Abstract
ERAP1 trims antigen precursors to fit into MHC class I proteins. To perform this function, ERAP1 has unique substrate preferences, trimming long peptides while sparing shorter ones. To identify the structural basis for ERAP1’s unusual properties, we determined the X ray crystal structure of human ERAP1 bound to bestatin. The structure reveals an open conformation with a large interior compartment. An extended groove originating from the enzyme’s catalytic center can accommodate long peptides and has features that explain ERAP1’s broad specificity for antigenic peptide precursors. Structural and biochemical analysis suggest a mechanism for ERAP1’s length-dependent trimming activity, whereby binding of long but not short substrates induces a conformational change with reorientation of a key catalytic residue towards the active site. ERAP1’s unique structural elements suggest how a generic aminopeptidase structure has been adapted for the specialized function of trimming antigenic precursors.
Conformation and solvent-accessibility of an MHC-I alpha-1 domain segment provide insight into the peptide receptive transition state (100.6)
Authors: Mage Michael , Wang Rui , Boyd Lisa , Revilleza Maria , Natarajan Kannan , Hansen Ted , Margulies David 
Published: January 2023

Abstract
MHC class I (MHC-I) molecules bound to antigenic peptides form the molecular structures recognized by MHC-I-restricted CD8+ T lymphocytes. On binding an antigenic peptide, the newly synthesized MHC-I sequesters a previously exposed region of the alpha-1 domain including residues 46-52, is released from tapasin, and proceeds to the cell surface. However, the changes in shape of MHC-I on peptide binding and release from tapasin remain unclear. We have determined four X-ray structures (from 1.64Å to 1.87 Å resolution) of an overlapping family of peptides from the H-2Ld alpha-1 domain (including residues 46-52) bound to the Fab fragment of 64-3-7, a mAb that reacts with peptide-receptive (PR) but not with peptide-loaded (PL) H-2Ld MHC-I. Positional differences of backbone and sidechain atoms of this alpha-1 domain segment, compared to the same segment in PL H-2Ld, indicate a significant conformational change on peptide loading. Among other changes, the side chain of the invariant Trp51 residue, and of Met52, although buried in PL MHCI, form extensive noncovalent bonds with mAb 64-3-7, indicating an external (solvent exposed) location in PR MHC-I. Furthermore, the 3(10) helix present in this segment of PL MHC-I is also present in the free peptide bound to MAb 64-3-7, and hence in the PR molecule. These findings help to delineate and provide insight into the conformational changes in MHC-I that accompany peptide loading. Supported by the intramural research program of the NIAID.
The role of immunoproteasomes in antigen presentation and thymic selection (100.7)
Authors: Kincaid Eleanor , Che Jenny , Welsh Raymond , Karow Margaret , Murphy Andrew , Valenzuela David , Yancopoulo George , Rock Kenneth 
Published: January 2023

Abstract
Proteasomes, multisubunit complexes that degrade cellular proteins, are instrumental in forming epitopes for MHC class I antigen presentation. An alternate set of catalytic proteasome beta subunits are induced by IFN-gamma and expressed constitutively in dendritic cells, T-cells and B-cells. Immunoproteasomes containing these inducible subunits have increased chymotryptic and tryptic activities and decreased caspase-like activity, and are hypothesized to produce more peptides suitable for binding to MHC class I. To date mutant mice lacking one or two of the immunoproteasome subunits have been generated and have revealed some changes in MHC class I antigen presentation. However, the overall role of the immunoproteasome is unclear because mice that completely lack all three subunits have not been produced up until now. We have generated mice that completely lack immunoproteasomes. These animals have reduced presentation of MHC class I-presented peptides, and the peptides that are presented appear to be substantially different than those on cells from wild type mice. Moreover, the phenotype of these animals is distinct from mice lacking any individual immunoproteasome subunit. The loss of immunoproteasomes also affects T cell development in the thymus. The phenotype of these animals will be discussed.
Enhanced IL-9 receptor (IL-9R) expression in CNS resident cells in the pathogenesis of EAE (101.31)
Authors: Ding Xiaoli , Yan Yaping , Li Ke , Zhou Fang , Zhang Guang-xian , Rostami Abdolmohamad 
Published: January 2023

Abstract
IL-9, which was originally identified in mice as a T cell growth factor, has attracted renewed interest because of the identification of its expression by multiple T helper cell subsets, including Th2, Th9, Th17 and regulatory T cells. It has been reported that IL-9 functions through activating its receptor to promote the cross-phosphorylation of JAK1 and JAK3, leading to the activation of STAT1, STAT3 and STAT5 and upregulating the transcription of IL-9-inducible genes. It remains unknown whether IL-9, in addition to being a key mediator of encephalitogenicity of Th17 and Th9 cells, directly affects CNS cells. In this report, we show that IL-9R expression was significantly increased in brain and spinal cord during the development of experimental autoimmune encephalomyelitis (EAE), an animal model of human multiple sclerosis (MS). The expression pattern increased with disease severity, and expression was highest at disease peak. Immunocytochemical staining showed that IL-9R was expressed by neurons, astrocytes, microglia and oligodentrocyte progenitor cells (OPCs). Interestingly, except for neurons, IL-9R expression in astrocytes, microglia and OPCs was significantly induced during EAE. These results suggest that IL-9 may directly exert its effect on CNS residential cells and therefore that manipulating IL-9 responsiveness in CNS cells will have important implications for treatment of EAE/MS.
β-catenin as a diagnostic marker and therapeutic target for the treatment of Type I diabetes (101.33)
Authors: Zirnheld Arin , Parnell Sarah , Kosiewicz Michele , Alard Pascale 
Published: January 2023

Abstract
We have found that NOD BMDC exhibit overexpression of β-catenin when compared to cells from diabetes-resistant B6g7 mice. We have found that the high levels of β-catenin in NOD BM-DC lead to the excess inflammatory cytokine production, especially that of IL-12, observed in Type I diabetes. The role of β-catenin in the development of diabetes and the mechanism by which it accumulates in NOD BM-DC remains to be determined. We have examined the cellular location and level of expression of the protein, the stages of disease at which it is overexpressed, its rate of degradation, its interactions with E-cadherin, and the impact of a β-catenin inhibitor on disease incidence and blood glucose levels. Our data show that NOD DC exhibit excess β-catenin expression in both whole cell and nuclear fractions, even before disease onset. We have found that NOD β-catenin is less rapidly degraded at early time points than that from B6g7 cells, suggesting that a defect in proteasomal degradation may allow for the accumulation of β-catenin. Additionally, we have found that β-catenin in NOD cells precipitates less E-cadherin, suggesting there may be a defect in the interaction between β-catenin and E-cadherin at the cell membrane. Finally, quercetin, a β-catenin inhibitor, appears to reduce disease development in NOD mice. These data point to the importance of β-catenin as a potential diagnostic marker and therapeutic target for reducing the inflammation that leads to Type I diabetes.
On the role of IL-1β and CNS myeloid cells in EAE pathogenesis (101.34)
Authors: Ronchi Francesca , Reboldi Andrea , Basso Camilla , Lanzavecchia Antonio , Sallusto Federica 
Published: January 2023

Abstract
IL-1β has been shown to play a role in several inflammatory disorders including mouse experimental autoimmune encephalomyelitis (EAE). We found that mice deficient for the apoptosis-associated speck-like protein containing a caspase recruitment domain, or ASC, did not develop EAE following immunization with MOG in CFA and pertussis toxin (PT). Autoreactive T cells were primed in wild-type (WT) and ASC-/- mice but expanded poorly in ASC-/- mice with reduced capacity to produce simultaneously several inflammatory cytokines, such as IL-17, IL-22, IFNγ, and GM-CSF. The induction of these T cells in WT mice but not ASC-/- mice was dependent on the presence of PT. PT was found to induce IL-1β secretion from antigen-presenting cells, such as DCs and microglia. These data suggest that the disease-inducing effect of PT may be due to its ability to induce production of IL-1β which in turn triggers differentiation of pathogenic multifunctional T cells. In addition to its effect in the induction phase, we are testing whether IL-1β, or other inflammasome-related cytokines, may be required in the effector phases of EAE. We found that ASC-/- mice are resistant to passive EAE induction. In addition, bone marrow chimera experiments of mice transplanted with bone marrow cells from WT mice or ASC-/- mice, showed that IL-1β production by microglial cells, CNS-resident myeloid cells and CNS-migrating inflammatory monocytes is important for EAE pathogenesis.