bluuebunny/crossref_metadata_2025_split huggingface dataset:
The downstream enhancer, Ed, positively regulates Ig kappa gene expression and somatic hypermutation
Authors: Xiang Yougui , Garrard William T. 
Published: June 2021

The mouse Ig kappa locus has three known enhancers: the MAR/intronic enhancer (MEi), the 3′enhancer (E3′) and the further downstream enhancer (Ed). Previous studies have shown that both MEi and E3′ enhancers are required for maximal gene rearrangement of the locus, and that E3′ is also required for maximal expression and somatic hypermutation (SHM). To functionally elucidate Ed in vivo, we generated knockout mice with a targeted germ line deletion of Ed. Ed deleted homozygous mice (Ed−/−) have moderately reduced numbers of kappa expressing B cells and correspondingly increased numbers of lambda expressing B cells in spleen. Ed−/− mice also have decreased kappa mRNA expression in resting and T‐cell dependent activated splenic B cells and reduced kappa chains in sera. However, our analysis indicates that kappa gene rearrangement is normal in Ed−/− mice. In addition, our results show that Ed−/− mice exhibit reduced SHM in the kappa gene J‐C intronic region in Peyer's patch germinal center B cells. We conclude that Ed positively regulates Ig kappa gene expression and SHM, but not gene rearrangement.Research supported by grants GM29935 and AI067906 from NIH and I‐0823 from the Robert A. Welch Foundation.
Are the KIR genes actively silenced prior to their tissue‐specific activation? A KIR intronic promoter produces spliced antisense transcripts in human ES cells
Authors: Anderson Stephen Kent , Li Hongchuan , Sharma Neeraj , Wright Paul W , Woll Petter , Kaufman Dan 
Published: June 2021

The KIR genes are in a silent methylated state in NK progenitors prior to their selective activation by developing NK cells. We have recently identified an additional antisense transcript originating in the second KIR intron. The KIR2DL1 antisense transcript is composed of three exons that contain: (1) a segment from intron 2; (2) exon 2 plus flanking intron sequences; (3) exon 1 plus the bidirectional promoter region. The composition of the spliced antisense KIR transcript (KIRaS) suggests that it functions to silence KIR gene expression. KIRaS was detected in human embryonic stem (ES) cells, an embryonal carcinoma (EC) cell line (Ntera2), and the HEK293 cell line, but not NK, T, or B cell lines. In vitro promoter analysis revealed that KIRaS promoter activity is only detected in the cell lines where transcript is present. Promoter activity is controlled by the MZF‐1 transcription factor that is expressed in totipotent hematopoieticcells and myeloid progenitors. KIR gene activation appears to be under the control of four distinct promoter units: distal forward; proximal forward or reverse; distal antisense. The potential interplay of the multiple KIR promoters and the timing of their expression during development will be discussed.Funded by NCI Contract N01‐CO‐12400
In situ imaging studies reveal different responses by naïve and memory CD8 T cells to late antigen presentation by lymph node DC after influenza infection
Authors: Cauley Linda S. , Khanna Kamal M. , Lefrancois Leo 
Published: June 2021

The lung draining lymph nodes (DLN) remain reactive for several weeks after pulmonary influenza virus infection while processed viral antigens continue to be presented to virus‐specific CD8 T cells. Scanning confocal microscopy has been used to analyze the response of naïve and memory influenza‐specific CD8 T cells to early and late antigen presentation. Naïve CD8 T cells responded to antigen that was in the DLN until at least 60 days after infection, but lost the ability to become fully differentiated effector cells as the time after infection increased. Many of the responding naïve T cells formed large stable clusters of dividing cells in the paracortex of the DLN where they remained in close association with DCs for up to a week after transfer. Central/memory cells also reached the DLN after the day 30 transfers, but showed no sign of a response to late antigen presentation in vivo or in vitro. In contrast endogenous NP‐specific CD8 T cells in the DLN exhibited signs of a response to late antigen presentation, but were phenotypically consistent with effector/memory cells that had been recruited to the DLN earlier in the response. These data show that naïve and memory CD8 T cells use distinct mechanisms to detect antigen‐bearing APC in some situations and that viral antigen continues to play an instructive in T cell migration long after infectious virus has been eliminated. The local changes in T cell migration have important implications for protective immunity since some acutely activated T cells can be retained near the site of infection, while other virus‐specific central/memory CD8 T cells are protected from exhaustion during late antigen‐presentation.This work was supported by the Damon Runyon Foundation (KMK) and National Institutes of Health grants AI065895 and AI071213. (LSC), DK45260 and AI41576 (LL).
Impairment of lung dendritic cell antigen presenting capacity by human paramyxovirus infections
Authors: Guerrero‐Plata Maria Antonieta , Kolli Deepthi , Ivanciuc Teodora , Casola Antonella , Garofalo Roberto P. 
Published: June 2021

Respiratory syncytial virus (RSV) and human metapneumovirus (hMPV) are major etiologic agents of severe respiratory tract infections. We have recently shown that both CD4+ and CD8+ T cells are virtually absent in lung of fatal cases of RSV‐positive lower respiratory tract infections, suggesting that this pathogen can severely inhibit T cell responses. Pulmonary dendritic cells (DC) are critical in regulating T cell‐mediated immune response in the respiratory tract. Therefore, we examined the effect of RSV and hMPV infections on the capacity of lung dendritic cells to stimulate T cells. RSV and hMPV induced a peak of CD11C+/MHC‐II+ DC recruitment (>3×106) to the lung by day 8 and 10, respectively. DC remained elevated by day 18 (1×106), when no virus is detected, compared to DC recruited in control mice (1×105). The capacity of lung DC to present antigen to T cells was impaired by RSV or hMPV infection as DC from infected mice showed a reduced capacity (> 65%) to present OVA peptide to CD4+ T cells, compared to DC from control mice. The impairment was observed despite the fact that MHC‐II and CD80 were upregulated. Importantly, we observed that expression of the negative T cell regulator PDL‐1 was also upregulated on DC from infected mice. In conclusion, this study demonstrates that RSV and hMPV may evade immune response by suppressing DC‐mediated T cell proliferation.NIH P01 062885, Flight Attendant Medical Research Institute
Characterizations of the virus‐induced differentiation of bone marrow plasmacytoid dendritic cells into CD11b+ dendritic cells
Authors: Liou Li‐Ying , Zuniga Elina I. , Oldstone Michael B.A. 
Published: June 2021

Plasmacytoid dendritic cells (pDCs), so called natural interferon‐producing cells (IPCs), can produce large amount of type‐I interferon (IFN‐I) upon virus infection. Intensive studies have shown that pDCs are also involved in activation and modulation of adaptive immunity. However, less is known about the regulation of their developmental plasticity during virus infection.Recently we demonstrated that bone marrow (BM) pDCs isolated from lymphocytic choriomeningitis virus (LCMV) infected mice differentiated into CD11b+ DCs in vitro. Here we provide in vivo evidence to prove the biological significance of our in vitro finding. We accomplished this by adoptive transferring pDCs isolated from LCMV infected mice and analyzing the immunoglobulin D‐J rearrangements (a genetic marker of pDCs) in CD11b+ DCs isolated from LCMV infected mice. Additionally, we demonstrated that the differentiation of pDCs into CD11b+ DCs does not rely on the infection of BM pDCs by LCMV, instead, is mediated by IFN‐I signaling. In preliminary studies we used pDC specific monoclonal antibodies against Ly49Q and Siglec‐H to characterize the pDC subtypes that differentiate into CD11b+ DCs. Collectively, our work indicates that BM pDCs constitute an important source for CD11b+ DCs during viral infection and further delineates the biological and phenotypic features of this novel DC developmental pathway.This work was supported by US. Public Health Service grant (AI 045927) and a training grant (NS041219) to L.L. from the National Institutes of Health.
Mechanisms of social stress enhancement of virus‐specific immune memory
Authors: Mays Jacqueline Wiesehan , Powell Nicole Damico , Bailey Michael T , Padgett David A , Sheridan John Francis 
Published: June 2021

Murine studies have demonstrated that the experience of social defeat (social disruption stress, SDR) before a primary influenza virus challenge augmented memory CD8+T cell responses to viral re‐challenge. Patterning of immune memory is established by the immune response to a primary infection, and the present study was designed to investigate potential mechanisms for memory enhancement during a primary challenge. C57BL/6 mice underwent 2 hrs of SDR per night for 6 nights (SDR‐INF group), which entailed introducing an aggressive mouse that physically defeated all resident mice. After night 6 of SDR, mice were intranasally infected with 1 HAU of influenza A/PR/8. Clonal expansion was significantly enhanced in the SDR‐INF group (p<0.05) for the immunodominant DbNP366+T cell subset, but not the DbPA224+ subset. SDR‐INF mice terminated viral replication significantly earlier than INF mice, and expressed more IFNγ mRNA prior to and during A/PR/8 infection. This study suggests that social defeat‐induced enhancement of virus‐specific immune memory occurs at the activation/clonal expansion phase of a primary infection, and is mediated by both cellular and environmental factors.Supported by NIH grants F30DE17068‐02, RO1MH46801‐13, T32DE014320‐04.
Tolerance to rat liver allograft after total lymphoid irradiation is mediated by CD4+CD25+ regulatory T cells
Authors: Fujiki Masato , Esquivel Carlos O , Martinez Olivia M , Strober Samuel , Krams Sheri M 
Published: June 2021

We have previously determined that post transplant total lymphoid Irradiation (TLI) induces tolerance in an experimental model of liver transplantation. The purpose of this study is to characterize the mechanism of TLI induced tolerance.TLI significantly prolonged survival in Lewis recipients of fully‐histoincompatible DA liver allografts with 88% of the recipients surviving long‐term (>100 days). CD4+CD25+Foxp3+ T cells were markedly increased in the liver grafts, PBMC, and spleen by day 35 post‐transplant and remained high in the spleen >100 days post‐transplant. Splenocytes from long‐term surviving recipients have a reduced alloresponse in MLR. Moreover, isolated splenic CD4+CD25+ T cells inhibited the MLR of naive Lewis splenocytes to DA splenocytes. Importantly, adoptive transfer of whole splenocytes into naive Lewis recipients of DA heart grafts significantly prolonged cardiac graft survival (MST whole splenocytes 33 days vs. control 18.5 days:p<0.01), whereas depletion of CD4+CD25+ T cells from splenocytes completely abrogated the prolongation of cardiac allograft survival (MST 16 days; p<0.01, vs. whole splenocytes).TLI induces tolerance to liver allografts via a mechanism involving CD4+CD25+Foxp3+ T cells that accumulate in the liver early after transplant and remain in the spleen >100 days. Studies using TLI to induce tolerance in clinical liver transplantation are currently underway.
Pancreatic Islets Engineered to Display on Their Surface an Exogenous FasL Protein Survive Indefinitely in Allogeneic Recipients
Authors: Zhao Hong , Yolcu Esma S. , Bandura‐Morgan Laura , Lacelle Chantale , Askenasy Nadir , Shirwan Haval 
Published: June 2021

Objective: To engineer pancreatic islets in a rapid and efficient manner with a novel form of FasL protein and test the efficacy of engineered islets for long‐term survival in allogeneic hosts.Methods: BALB/c islets were engineered by cell surface modification with biotin followed by the display of a chimeric form of FasL protein with core streptavidin (SA‐FasL). SA‐FasL‐engineered islets were transplanted into streptozotocin diabetic C57BL/6 mice under transient cover of rapamycin.Results: All the islets showed effective engineering with SA‐FasL, which persisted on the surface of islets for weeks in vitro as assessed by confocal microscopy. All the islets (n=23) with SA‐FasL survived over 100–360 days without detectable signs of rejection. In marked contrast, all the unmodified (n=9) and SA‐engineered (n=14) islets underwent acute rejection within 40 days. The observed tolerance was localized to the engineered islets as unmodified second set of islets transplanted under contralateral kidney of long‐term (>90 days) graft recipients were rejected in a normal tempo (MST=17 ± 9 days) without any effect on the survival of primary islets.Conclusion: Engineering pancreatic islets with exogenous immunomodulatory molecules, such as SA‐FasL, in a rapid and efficient manner represents a novel means of immunomodulation with considerable therapeutic potential. NIH (R21 DK61333, R01 AI47864, R21 AI057903, R21 HL080108), JDRF (1‐2001‐328), and ADA (1‐05‐JF‐56).
Vascularized bone marrow transplant (VBMT) serves as a novel surgical approach to stem cell transplantation and stimulates normal repopulation of lymphocytes in the spleens of irradiated (XRT) rat hosts
Authors: Licata Lauren , Rojavin Yuri , Patel Mitul , Tai Chau , Strande Louise , Matthews Martha , Hewitt Charles 
Published: June 2021

Our lab demonstrated that VBMT, the microsurgical transplantation of a femur with its vascular pedicle, can induce immune tolerance across a semi‐allogeneic barrier without graft versus host‐disease. We hypothesized that VBMT alone is potentially superior to cellular stem cell transplantation and sufficient to induce normal repopulation of the spleens of XRT rat recipients.Lewis Brown Norway rats received 9 Gy radiation. Rats then received either a conventional cellular (cBMT, n=5) or VBMT (n=4) bone marrow transplant from Lewis donors. Control groups were: non‐transplanted, non‐irradiated (CT, n= 5) or XRT only (n= 4). Stained histologic sections of spleens were analyzed with digital image analysis (DIA).XRT rats died 9±1 days post irradiation. Other groups were sacrificed: cBMT at 110 days; VBMT at 102 ±1 days. Compared to CT, XRT spleens showed white pulp atrophy; cBMT had less white pulp but appeared hypercellular and VBMT spleens appeared normal. DIA results can be seen in the table below:VBMT is capable of reconstituting spleens of XRT semi‐allogeneic recipients similar in appearance to normal rats. This model has clinical relevance for both stem cell transplantation and solid organ transplantation, in that VBMT induces chimerism and tolerance.
ST2L upregulation promotes maturation resistance in rapamycin‐conditioned dendritic cells
Authors: Turnquist Heth Roderick , Sumpter Tina L. , Nau Gerard J. , Thomson Angus W. 
Published: June 2021

Objective: Maturation resistance and tolerogenicity can be conferred on dendritic cells (DC), ‐crucial regulators of T cells, by exposure to rapamycin (RAPA), a tolerance‐sparing immunosuppressant. The mechanisms underlying this acquired unresponsiveness, typified by diminished responses to Toll‐like receptor (TLR) ligation, have not been identified. Thus, our objective was to elucidate a molecular basis for RAPA‐induced DC maturation resistance.Methods: RAPA administration was used to condition splenic DC in vivo and bone‐marrow derived DC in vitro. DC maturation was monitored by assessment of co‐stimulatory molecule expression and allostimulatory capacity. To identify negative regulators of maturation, microarray analysis and quantitative RT‐PCR was completed, and findings confirmed via Western and flow cytometric analyses.Results: DC conditioning with RAPA promotes overexpression of the IL‐1 receptor(R) family member, ST2L, and enhances its surface expression. ST2L is the receptor for IL‐33 and has also been implicated as a negative regulator of TLR signaling. Consistent with this regulatory function, induced ST2L expression suppressed the responsiveness of RAPA‐DC to TLR ligation.Conclusion: This work identifies a novel mechanism by which a clinically‐important immunosuppressant impedes the capacity of DC to mature and consequently stimulate effector/adaptive T cell responses.
The Evolution and Diversity of IGG
Authors: Butler John , Wertz Nancy , Kacskovics Imre 
Published: June 2021

Immunoglobulin G (IgG) is the flagship mammalian antibody with evolutionary roots in amphibian IgF. Cartilaginous and bony fish have only two antibody isotypes; IgM and IgD. IgD is structurally diverse and seems to have disappeared in birds, in egg‐laying and marsupial mammals and even some eutherian mammals. Meanwhile, IgG emerged as the “mammalian antibody”. Like is often true, evolutionary emergence is associated with evolutionary divergence making mammalian IgG an interesting topic for studies on the evolutionary diversification of a gene family. Gene duplication produced an array of IgG subclasses ranging from only one (rabbits) to seven (horses) with all other possibilities in between. Swine have six putative subclasses of IgG with at least two alleles known for five of these. IgG3 is monomorphic and closest to the “stem IgG lineage” among mammals. Alternative splicing is common in the CH2 domain, potentially allowing swine to express >20 different IgG antibodies.Understanding the evolution of IgG among mammals has practical implications. Since speciation preceded subclass diversification investigators should not extrapolate the function of e.g. IgG1 in one species to an IgG of the same name in another. All of this begs the question as to why this antibody class evolved and diversified exclusively among mammals. Perhaps it is their ability to utilize Fc receptor‐mediated events like opsonization, ADCC, transepithelial transport or cellular re‐cycling which protects IgG from catabolism extending its half‐life. All of these provide survival advantage to especially offspring that have not yet developed their own adaptive immune response.
Infection of dendritic cells with the American, but not the European, PRRSv genotype induces Treg (Foxp3+CD25+) cells.
Authors: Hernandez Jesus , Silva Erika , Reséndiz Mónica , Flores Lilian , Fraile Lorenzo , Montoya Maria 
Published: June 2021

The potential of PRRSv‐infected dendritic cells (DCs) to induce Foxp3+CD25+ T‐regulatory cells was evaluated in vitro using two American and five European strains. Monocyte‐derived DCs were infected, cultured for 24 h and in some cultures were treated with IFN‐α. Infected DCs were co‐cultured with autologous non‐adherent cells for 5 days and some cells stained with CFSE. Cytokines were quantified by qPCR and by ELISA, whereas the expression of Foxp3+ and CD25+ was analyzed by FACS. Our results showed that American, but not European, type viruses reduced T cell proliferation. The addition of IFN‐α did not affect T cell proliferation but it inhibited the ability of PRRSv to replicate. DCs infected with American type increased the number of T cells expressing Foxp3+CD25+ phenotype and IFN‐α reduced the generation of this cells. Surprisingly, European type did not induce T cells with Foxp3+CD25+ phenotype. The expression of IL‐10 mRNA was 3 fold higher in DCs infected with American type as compared to DCs infected with the European type. Finally, American type increased the expression of TGF‐β; mRNA five fold. In conclusion, these results suggest that American, but not European type PRRSv, induce the expression of T‐regs cells (Foxp3+CD25+), and this induction could be dependent on TGF‐β.Funded by SEP‐CONACyT (43602) Mexico, and SMES (AGL2005‐07073‐C02‐02) Spain.
Comparative innate immune gene expression in chicken intestine after in vivo challenge with commensal (Campylobacter) and pathogenic (Salmonella) bacteria
Authors: Shaughnessy Ronan Gerard , Meade Kieran G. , Cahalane Sarah , Allan Brenda , Reiman Carla , Farrelly Cliona O' 
Published: June 2021

Campylobacter jejuni is a commensal bacterium in chickens and a major cause of food poisoning in humans. It is unknown whether the intestinal immune response has a role in establishing the commensal state. The innate immune responses of 4 week‐old broiler chickens to C. jejuni challenge (108 bacteria) were studied and compared with an avian pathogen, Salmonella enterica. Challenged and control birds were sacrificed 6 hours post‐challenge, RNA was extracted and cDNA synthesised. Selected genes involved in pathogen detection and innate immune response to bacterial infection were profiled in the caecum by quantitative real‐time PCR.A significant increase in the expression of TLR21 was observed after challenge with both types of bacteria (P < 0.05) compared to control birds. TLR4 expression was increased 4‐fold after C. jejuni challenge only (P = 0.02). IL6 was increased in response to both commensal and pathogenic challenges (P < 0.02). In contrast, IL8 mRNA expression was decreased 4‐fold in response to C. jejuni but increased 5‐fold to S. enterica challenge (P = 0). Antimicrobial peptides were differentially expressed in both models. Specifically, AvBD6 was increased by 24‐fold in response to S. enterica infection (P = 0).Results indicate that C. jejuni induces early innate immune gene expression changes, some similar to and others distinct from pathogenic challengeFunding: FIRM, Ireland
Model to estimate in vivo enrichment of beef muscle and liver with 14C‐vitamin B12 (14C‐B12)
Authors: Garrod Marjorie G , Johnson Heidi A , Calvert Christopher C , Allen Lindsay H , Green Ralph , Miller Joshua W 
Published: June 2021

Beef enriched in vivo with 14C‐B12 may be used for assessing B12 bioavailability and absorption in humans. However, B12 transfer rates between plasma and tissues in bovines are not well characterized. We created a model of B12 kinetics based on data collected from two 500 lb calves: calf 1 received two I.V. pulse doses of 14C‐B12 (7.5 μg, 250 nCi/dose) given 24h apart; calf 2 received a continuous infusion of 14C‐B12 (22.5 μg, 750 nCi) for 21d using an Alzet pump. 14C content of plasma, liver and muscle was determined by accelerator mass spectrometry. The model is composed of 4 state variables representing B12 pools in blood, liver, muscle, and other tissues. Exchanges between pools were predicted based on mass action kinetics. Using pulse dose data, uptake rates from plasma into muscle and liver were concentration dependent and estimated to be 5.5%/d and 3.9%/d, respectively. Using continuous infusion data, uptake rates from plasma into muscle and liver were concentration independent and estimated to be 0.072 nmol/d and 0.141 nmol/d, respectively. Model estimates of 14C‐B12 accumulation in liver and muscle were within 30% of measured values. SDs of the estimated exchange rates were low indicating rate predictions were unique. This model can provide estimates of B12 enrichment in meat and liver using different dosing protocols.Funding: National Cattlemen's Beef Association