bluuebunny/crossref_metadata_2025_split huggingface dataset:
Characterization of an IgM linear epitope involved in interaction with the catfish soluble FcRI receptor (81.6)
Authors: Nayak Deepak K , Wilson Melanie , Miller Norman , Bengtén Eva 
Published: January 2023

Abstract
The IgM binding properties of a recently identified soluble Fc receptor (IpFcRI) from channel catfish, Ictalurus punctatus, were examined. Recombinant (r) IpFcRI protein was used to assess binding to native as well as reduced IgM in latex bead immunoassays and Western blot analyses. rIpFcRI was found to recognize catfish native IgM, as well as reduced IgM heavy (μ) chain. To map the IpFcRI docking site, IgM constant (Cμ) domains Cμ1, Cμ2, Cμ3, and Cμ4 were expressed in E. coli and only the rCμ3 and rCμ4 were found to retain IpFcRI binding properties. Subsequently, rCμ3 and rCμ4 were split into three sub-regions in order to locate the binding site residues. By sequence analyses an octapeptide (FxCxVxHE) present in both Cμ3 and Cμ4 was identified as the putative IpFcRI binding site. Using overlapping oligopeptides, IpFcRI was shown to bind this octapeptide motif in dot blot analyses. In addition, since this motif is also present in other vertebrate immunoglobulins (Ig), including rainbow trout, chicken and mouse, Igs from various species were examined, and IpFcRI binding was shown only in Igs that contained this specific motif. Supported by NIH grant R01 AI19530 and UMMC IRSP 59908.
Rag deletion in peripheral T cells prevents TCR revision (82.10)
Authors: Hale Scott , Fink Pamela J 
Published: January 2023

Abstract
In Vβ5 TCR transgenic (Tg) mice, CD4+Vβ5+ T cells are reactive to a peripherally expressed endogenous superantigen. Most self-reactive CD4+ T cells are deleted in the periphery, but through the process of TCR revision, some lose Vβ5 surface expression, re-express Rag genes, undergo rearrangement of endogenous TCRβ, and express a newly formed TCR. As Vβ5 Tg mice age, TCR revision results in the accumulation of post-revision CD4+TCRβ+Vβ5- cells.
We now show that post-revision CD4+ T cells undergo extensive homeostatic proliferation in lymphopenic hosts. MHC drives maximal proliferation. Additionally, post-revision CD4+ T cells in Vβ5 Tg mice generate an antigen-specific IFNγ response to Listeria infection.
To further investigate the importance of TCR revision, we devised a strategy for removing the Rag2 gene in peripheral T cells. Mice bearing a floxed Rag2 gene and a Cre transgene driven by the distal lck promoter were crossed to ROSA26 YFP reporter mice, in which YFP reports Cre activity. Adoptive transfer of sorted Vβ5+YFP+ T cells from control Rag+/+ mice results in the generation of post-revision T cells, while Vβ5+YFP+ T cells from Ragfl/fl mice remain Vβ5+.
Our results illustrate that TCR revision contributes to the ongoing immunocompetence of Vβ5 Tg mice, and that Rag expression in peripheral T cells is necessary for the generation of Vβ5-CD4+ T cells in Vβ5 Tg mice.
This work was funded by NIH RO1 Grant #AG13078.
The effects of an aged microenvironment on mature B cell homing and distribution of CXCL13 (82.13)
Authors: Minges Wols Heather A. , Ippolito Jill A. , Birjandi Shirin , Ziegler Nicole , Witte Pamela L. 
Published: January 2023

Abstract
The splenic architecture in many aged mice appears disrupted, with some similarities to the disorganization observed in mice lacking the chemokine, CXCL13. Particularly, small follicles and germinal centers are reported and the marginal zone (MZ) appears disrupted. Changes in the proportion of B cell subsets in bone marrow (BM) and secondary lymphoid tissue suggest that migration patterns may be altered. We tested the ability of young splenic B cells to migrate in an aged microenvironment. Of note, donor B cells significantly increased homing to BM in an old host. Nonetheless, similar numbers of donor follicular B cells were found in the spleens and localized to the follicles of aged vs. young recipients. However, fewer donor MZ B cells migrated into aged spleens. Unexpectedly, CXCL13 protein levels, assessed by ELISA, were greater in spleens from aged mice, but differences were apparent in the histological distribution of CXCL13 protein between young and old spleens. In old spleens, CXCL13 was unevenly distributed, concentrated in patches throughout the follicles, and reduced or absent at the follicular edge. The data suggest that CXCL13 expression may be dysregulated in aged mice. While the consequences of changes in CXCL13 distribution are under investigation, it appears not to directly affect follicular B cell migration and may have more impact on MZ B cells. NIH R01AG013874 and CCC Faculty Development Grant.
Foxo1 links trafficking and survival of naïve T cells through regulation of L-selectin, Ccr7 and IL-7Rα expression (82.17)
Authors: Kerdiles Yann M , Beisner Daniel R , Tinoco Roberto , Dejean Anne S , Castrillon Diego H , DePinho Ronald A , Hedrick Stephen M 
Published: January 2023

Abstract
Foxo transcription factors play an evolutionary conserved role in cellular and organismal adaptation to nutrients and growth factor availability. Here we show that, in accord with its preferential expression in lymphocytes, the transcription factor Foxo1 plays a non-redundant role in peripheral naïve T cell homeostasis. Our experiments demonstrate that in naïve T cells Foxo1 controls the expression of the homing receptors L-Selectin and Ccr7 as well as the transcription factor Klf2, and its deletion is sufficient to alter lymphocyte trafficking in vivo. In addition, Foxo1 deficiency is associated with a severe defect in IL-7Ra expression, correlated with the ability of Foxo1 to directly bind an evolutionarily conserved region upstream of the Il7ra transcriptional start site. Finally, in agreement with the regulatory mechanisms controlling Foxo activity, we show that growth factor withdrawal induces a specific Foxo1-dependent increase in L-selectin, Klf2 and IL7ra expression. Overall, these data support a model where the regulation of Foxo1 activity depending on growth factor availability regulates optimal homing and detection of survival signals.
Examining the Role of AP-1 in T cell Development Through Overexpression of BATF Transcription Factors (82.7)
Authors: Jordan Kimberly L , Betz Briana C , Logan Michael R , Taparowsky Elizabeth J 
Published: January 2023

Abstract
The classical AP-1 dimer of Jun and Fos binds to DNA in a sequence specific manner to activate target gene transcription. The BATF family of basic leucine zipper (bZIP) transcription factors form heterodimers preferentially with Jun proteins. These BATF:Jun dimers bind to the same DNA target sequence as the Jun:Fos heterodimer, but do not activate gene transcription. BATF1 and BATF3, two members of the BATF family, are expressed in lymphoid cells. Our lab has generated transgenic mice overexpressing BATF1 or BATF3 in T cells using the human CD2 promoter. The BATF1 and BATF3 transgenic mice demonstrate an increase in CD4+ T cells and a marked decrease in NKT cell numbers. Additionally, both BATF1 and BATF3 transgenic mice demonstrate a marked increase in circulating immunoglobulin levels. Interestingly, only BATF1 transgenic mice demonstrate decreased numbers of NK cells and increased IL-17 production. Our most recent findings reveal a high frequency (&gt;95%) of lymphoid tumors in BATF1, BATF3, and BATF1/3 transgenic mice. These results suggest that the phenotypes that occur as a result of chronic inhibition of AP-1 activity in the T cell lineage predisposes BATF mice to develop a lymphoproliferative disorder resembling T cell lymphoma.
In vitro derivation of marginal zone B cells from CD23- precursors (82.8)
Authors: Roundy Kirstin M , Weis John H 
Published: January 2023

Abstract
B cell development has been portrayed as proceeding in a linear fashion; specifically, newly formed B cells migrate from the bone marrow to the spleen where they develop into transitional B cells (T1 and T2), which give rise to marginal zone (MZ) and follicular mature (FM) B cells. Previously, we hypothesized that MZ B cells can develop from a T1 B cell without passing through a T2 developmental stage. We have developed an in vitro culture system that allows immature splenic and bone marrow cells, when cultured in the presence of B cell activating factor (BAFF) and Notch ligand, delta-like-1 (DL1), to develop into mature FM and MZ B cells. Cells cultured with only Notch or BAFF signaling did not assume a MZ phenotype. To further investigate the ability of immature B cells to develop into MZ B cells, we separated immature cells based on CD23 expression and cultured them in the presence of Notch and BAFF. CD23- populations isolated from total splenocytes or B220+ cells yielded the most MZ-like B cells in culture. When CD23+ cells were cultured, most cells retained expression of CD23 and failed to develop into MZ B cells. However, a small percentage of CD23+ cells decreased CD23 expression, yielding a population of cells with a MZ phenotype. These data suggest that the majority of MZ-like B cells in culture were derived from CD23- cells and support the hypothesis that many, if not all, MZ cells in vivo are derived from a CD23- T1-like intermediate.
The length of the secondary stimulus controls the magnitude of recall responses by CD4+ T cells (83.10)
Authors: Ravkov Eugene V , Williams Matthew A 
Published: January 2023

Abstract
The parameters controlling the generation of robust CD4+ T cell recall responses remain poorly defined. In this study we compared recall responses by CD4+ and CD8+ memory T cells following rechallenge. Homologous rechallenge of mice immune to either lymphocytic choriomeningitis virus (LCMV) or Listeria monocytogenes resulted in robust CD8+ T cell recall responses but poor boosting of CD4+ T cell recall responses in the same host. In contrast, heterologous rechallenge with a pathogen sharing only a CD4+ T cell epitope resulted in robust boosting of CD4+ T cell recall responses. Robust CD4+ and CD8+ T cell recall responses were simultaneously induced following rechallenge with peptide-pulsed dendritic cells, ruling out the possibility that the disparity in CD4+ and CD8+ T cell recall responses could be attributed to competition for growth factors or APCs. Instead, CD4+ T cell recall responses were dependant on the duration of the secondary challenge. Increasing the rechallenge dose resulted in more potent boosting of CD4+ T cell recall responses, and artificially limiting the duration of infection following heterologous rechallenge adversely impacted the magnitude of CD4+ T cell, but not CD8+ T cell, recall responses. These findings suggest that rapid pathogen clearance by secondary CTL following homologous rechallenge prevents optimal boosting of CD4+ T cell responses.
Clonotypic density and cross-reactivity of the CD8+ memory T cell repertoire in adults. (83.12)
Authors: Petrova Galina , Gorski Jack 
Published: January 2023

Abstract
Adult memory T cell repertoires are populated by clonotypes that correspond to an individual's history of antigen exposures. The population density of clonotypes in the memory repertoire is important in light of the greatly reduced production of naïve T cells by the involuted thymus and the continuing need to respond to novel pathogens. We measure clonotypic density by comparing the recall response to the influenza-derived, HLA-A2 restricted, M158-66 peptide, with those to peptides substituted at positions 63 and 65 (TCR contact residues). The PBMC were from individuals who show a complex repertoire in recall response to the M158-66 peptide. All samples were obtained under an IRB approved protocol. Peptide-specific responses were identified by CDR3 spectratype analysis, and the clonotypes identified by sequencing the CDR3. As the substitutions became more pronounced, the M158-66 repertoire was lost and new responding clonotypes were revealed. However, the number of new clonotypes identified was lower than observed for M158-66. Structurally similar substitutions revealed a limited cross-reactivity in M158-66 repertoire. These data indicate that the adult repertoire is populated by T cells that can recognize structurally related epitopes. However, these T cells are sparsely distributed for the peptide:MHC structures generated by our substitutions.
Caveolin-1 expression in CD8 T cells positively regulates CD8 T cell function and burst size (83.15)
Authors: Tomassian Tamar  Kathy , Liu Scot Daren , Miceli M. Carrie 
Published: January 2023

Abstract
Caveolin-1 (Cav-1) is a molecular scaffold involved in lipid raft organization as well as protein and membrane trafficking, cytoskeletal reorganization, and regulation of signal transduction in several cell types. Despite initial reports suggesting that cav-1 is not present in lymphocytes, we have identified cav-1 expression in murine T cells by immunoblotting lysates from purified primary T cell populations. We also show that cav-1 positively regulates TCR/CD28 induced CD8 T cell activation. CD8 T cells from cav-1 knockout (KO) mice hypoproliferate and undergo 2 to 3-fold fewer cell divisions in response to 48 hrs of TCR/CD28 engagement relative to wildtype (WT) CD8 cells. Indeed, cav-1 KO CD8 T cells had a lower percentage of live cells and more cells undergoing apoptosis after 48 and 72 hrs of stimulation. To determine if cav-1 regulates CD8 T cell responsiveness in vivo, WT and cav-1 KO mice were challenged with LCMV. We found that cav-1 KO mice have both a lower percentage and absolute number of virus specific CD8 cells, providing an in vivo correlate to our findings in vitro. Further, to determine if cav-1 function is T cell intrinsic, we adoptively transferred cav-1 KO OT-1 cells into WT hosts and challenged with LM-OVA. Our findings show that cav-1 KO donor cells expanded less than WT donor cells, suggesting that cav-1 expressed by CD8 cells regulates burst size. Currently we are working to assess cav-1 subcellular localization during T cell synaptogenesis and elucidate the molecular basis of its activity. These findings identify cav-1 as a novel positive regulator of CD8 T cell activation and cell survival.
T. Tomassian is predoctoral trainee recipient of the Microbial Pathogenesis Training Grant 2-T32-AI-07323.
Expression of the B cell-specific Src family kinase Blk in γδ T cells (85.13)
Authors: Laird Renee M , Hayes Sandra M 
Published: January 2023

Abstract
There are two T lineages, αβ and γδ, which are defined by the antigen-binding heterodimers contained within their antigen receptors. While it is still not known why two T lineages are conserved in all jawed vertebrates, years of study demonstrate that αβ and γδ T cells recognize different antigens and have unique roles in immunity. We have previously shown that αβ - and γδTCRs differ not only in the subunit composition of their signaling modules but also in their ability to transduce signals. We hypothesize that this difference in signal transduction is due to differences in the signaling pathways coupled to the αβ - and γδTCRs. To test this, we used global gene expression profiling to identify signaling molecules that are differentially expressed in αβ and γδ T cells. Unexpectedly, we found that Blk, a Src family kinase expressed in B cells, is expressed in γδ T cells but not in αβ T cells. We developed an intracellular flow cytometric assay to examine the pattern of Blk expression during T cell development. Using this assay, we detected Blk in CD25+ lineage-negative thymocytes, which contain precursors with the developmental potential to become either αβ or γδ T cells. Blk was also found to be expressed in γδ thymocytes but not in CD4+CD8+ thymocytes, suggesting that Blk expression is retained in γδ lineage cells but turned off in αβ lineage cells. We are currently investigating whether Blk plays a role in the development γδ T cells.
Age-related thymic involution is associated with loss of medullary epithelial subsets and regulated by Foxn1 (86.1)
Authors: Su Dong-Ming , Sun Liguang , Guo Jianfei , Cheng Lili , Tvinnerim Amy 
Published: January 2023

Abstract
Age-related thymic involution results from deterioration of the interaction between hematopoietic progenitors and non-hematopoietic thymic epithelial cells (TECs). The involution may be primarily triggered by deterioration of TECs. Therefore we focus on the role of TEC-autonomous gene Foxn1, which is largely undefined in postnatal thymic function and aging. We generated a conditional Foxn1 knockout mouse (fx). Through a tamoxifen-inducible ubiquitous Cre (uCreERT), a postnatal deletion of Foxn1 caused dramatically acute thymic involution within 5 days. The involution was associated with more impairment in medullary TECs (mTECs) than in cortical TECs, especially MHC-IIhiUEA-1hi and K5+ mTECs. The phenotypes were very similar to the naturally aged murine thymus, in which the MHC-IIhiUEA-1hi mTEC subset had a decrease correlated with age, and coincided with reported results showing that the K5+ mTECs were reduced in the naturally aged thymus (Gui. J. Int. Immuno. 07). A more physiologically relevant progressive loss of Foxn1 via a low level of spontaneous activation of the uCreERT transgene in CreERT-fx/fx and CreERT-fx/+ mice caused the similar effects, including acceleration of thymic involution, reduced K5+ mTECs and MHC-IIhiUEA-1hi mature mTECs with age, beginning at 3 months of age, which is much earlier than that in fx/fx and wild type mice. Combining with previous report that naturally aged mice have gradually reduced Foxn1 mRNA expression, we believe that Foxn1 is involved in age-related thymic involution through impairment of specific epithelial cell subpopulations. It causes deterioration of the postnatal thymic microenvironment, thereby triggers the thymic involution. (Partially supported by grants from NIAID/NIH to DMS).
Correlating expression of syndecan 1, a novel marker for certain thymocytes, with development into unique alpha/beta T cell lineages (86.3)
Authors: Hamad Abdel Rahim , Xiao Zuoxiang , Li Meng , Schneck Jonathan , Mohamood abdiaziz 
Published: January 2023

Abstract
Identification of specific markers of thymocytes that develop into specialized lineages is important for understanding thymic differentiation and lineage commitment. We have recently shown that double-negative (DN) but not conventional T cells express syndecan 1 (sdc1), a major heparan sulphate proteoglycan previously known to be expressed by intestinal epithelia and plasma cells. Here we show a highly restricted expression of sdc1 by a small subset of cells of the αβ lineage during thymic development. Unlike mainstream (sdc1-) thymocytes, sdc1+ thymocytes developed mainly into CD4-CD8-TCRαβ + DN T cells including NKT cells. Sdc1 expression on this small subset was first detected at the DN4 stage, indicating that it was not induced by TCR-MHC interactions. Distribution of sdc1+ thymocytes among the double-positive (DP) thymocyte pool was limited to distinct (TCRβlowCD4lowCD8low) cells. β2m-deficiency blocked maturation of sdc1+TCRαβ + DN cells without affecting the immature subset development. A few sdc1+ thymocytes were selected on MHC class II into CD4 T cells. The existence of phenotypically definable thymocytes such as sdc1-expressing cells within the immature (DN4 and DP) pool suggests that early thymocytes include unique lineage committed precursors that have not been previously identified due to the lack of specific markers.
Funding: NIH DK069279 and DK066039.
Interferon gamma-dependent alterations in the hematopoietic stem cell pool during infection (87.4)
Authors: MacNamara Katherine C , Oduro Kwadwo , Racine Rachael , Choi Kyunghee , Winslow Gary 
Published: January 2023

Abstract
Infection with Ehrlichia muris induces blood cytopenias and a decrease in bone marrow (BM) cellularity and function. Here we addressed whether infection altered hematopoietic stem cells (HSCs) and progenitor cells. We observed changes in the frequency of BM HSCs by day 8 post-infection; lineage-negative (Lin-), c-Kit-, Sca-1+ progenitor cells were absent, and the Lin- population was composed entirely of c-Kit+, Sca-1+ cells (LSK). In addition, common myeloid progenitors (Lin-, Sca-1-, c-Kit+, CD127-) were diminished and common lymphoid progenitors (LSK, CD127+) were increased. Competitive reconstitution experiments revealed that LSK cells isolated from infected mice gave rise to predominantly B lymphocytes, suggesting that infection favored lymphopoiesis. We next stained Lin- cells for expression of other markers for HSCs (CD150, CD48, and CD244) which revealed that the LSK population were likely true long-term reconstituting HSCs (CD150+, CD48-, CD244-) and multipotential progenitors (CD150-, CD244+, CD48-). We examined several knockout strains in our infection model and found that interferon gamma (IFNg)-deficient mice exhibited reduced CLPs after infection, suggesting that IFNg contributes to alterations in the HSC pool. Current research is aimed at understanding the specific requirement of IFNg in processes that govern HSC self-renewal, differentiation, and mobilization.
The concerted action of GM-CSF and Flt3-ligand on in vivo DC homeostasis (87.9)
Authors: Kingston Dior , Schmid Michael A , Onai Nobu , Obata-Onai Aya , Baumjohann Dirk , Manz Markus G 
Published: January 2023

Abstract
Dendritic cell (DC) development is efficiently supported by Flt3-ligand (FL) or GM-CSF in vitro, and lymphoid-organ DC maintenance in vivo is critically dependent on FL. However, the importance of GM-CSF or both cytokines for non-lymphoid organ DC homeostasis is not well defined. Here, we show that Gm-csfr and Flt3 expression in progenitor and myeloid cells correlate with the phenotype seen in the cytokine knock-out (KO) mice. Compared to wild-type, DC progenitor numbers are similar or only slightly decreased in GM-CSF-KO mice, but two-fold decreased in FL-KO mice. Spleen and lymph node cDCs are two- to three-fold reduced in GM-CSF and ten-fold reduced in FL-KO mice, while pDC numbers are only affected by FL deficiency. Epidermal DCs are equally moderately reduced, while dermal DCs are reduced to about two thirds in GM-CSF-KO and half in FL-KO mice. Compared to FL-KO mice, combined lack of GM-CSF and FL leads to a further significant reduction of DC progenitors and dermal DCs. In line with reduction of respective DCs, proliferative T cell and specific IgG responses are reduced progressively from wild-type to GM-CSF- to FL- to double-deficient mice. These data demonstrate the concerted action of GM-CSF and FL on DC maintenance.
This work was supported by the Swiss National Science Foundation and the European Commission FP6 Network of Excellence initiative (DC-THERA and MUGEN).