bluuebunny/crossref_metadata_2025_split huggingface dataset:
Activated human CD25+B cells are able to induce cell cycle arrest and apoptosis in CD4+T‐Helper cells
Authors: Tretter Theresa , Venigalla Ram Kumar , Eckstein Volker , Saffrich Rainer , Hanns‐Martin Lorenz 
Published: June 2021

B cells play an important role as APC. However several hints indicating an additional regulatory role remain to be elucidatedMethods: CD19+B and CD4+T cells were separated from human PBMC by MACS. B cells were prestimulated with SAC or αIgM/IgG, irradiated and cocultured with CD4+T cells and αCD3+IL‐2 or αCD3+αCD28. T cell proliferation was determined by 3H Thymidine incorporation or PKH‐26 and apoptosis by AnnexinVResults: T cell proliferation and cytokine production (IL‐10, IFNg) under optimal stimulatory conditions was inhibited by more than 70% in presence of preactivated, FACS‐sorted, large CD25+B cells vs. small CD25‐B cells. Suppression was strictly dependent on cell‐contact and constant presence of B cells as determined by cell culture inserts and reconstitution of cell division after removal from B cells. Blocking IL‐2Rα/β on B cells abolished suppression by about 50%, as did decreasing concentrations of IL‐2, suggesting that B cell suppressor activity is determined by the amount of IL‐2 available. Further, B cells induced apoptosis in a subpopulation of T cells (37% vs 17% after 24h) independent from blocking the CD95‐CD95L pathwayConclusions: Polyclonally activated CD25+B cells are able to costimulate or suppress T cell mediated responses, depending on activation status and environmental conditions. Future experiments deal with the mechanisms behind and their pathophysiological impact.
DNA breaks in immunoglobulin Class Switch Recombination that depend on UNG but not AID
Authors: Max Edward E. , Arudchandran Arulvathani , Bernstein Ralph M. 
Published: June 2021

B lymphocytes switch from secreting IgM to secreting IgG, IgA or IgE through a DNA recombination, Class Switch Recombination. CSR is thought to be triggered by Activation Induced Deaminase (AID), which is believed to deaminate cytosines to uracil in Switch region DNA. Excision of uracils by uracil DNA glycosylase (product of the UNG gene) generates abasic sites, which are targeted for the DNA cleavage required for CSR. Consistent with this model, CSR‐related double‐strand breaks (dsbs) – detected by Ligation Mediated PCR (LMPCR) ‐‐ have been reported to be dramatically reduced in either AID−/− or UNG−/− B‐cells. Here we examine single‐strand breaks (ssbs) using LMPCR and report, surprisingly, that CSR‐related antisense‐strand breaks in Sμ and Sγ regions are dependent on UNG but not AID, suggesting participation of a cytosine deaminase other than AID. This conclusion is supported by the sequences at these DNA breaks, which show a bias for a consensus sequence different from that reported for AID. The ssbs appear to be part of the normal CSR pathway, since in B cells in which CSR is blocked by deletion of Sμ, the content of Sγ ssbs is elevated, as though ssbs persist in the absence of a recombination partner for completing μ‐to‐γ CSR. These results suggest a narrower role for AID in CSR than previously recognized, and prompt a search for a putative alternative cytosine deaminase participating in CSR.Supported by FDA funds.
Influence of IgA expression on T‐Dependent and T‐Independent antibody responses
Authors: Kirimanjeswara Girish Soorappa , Salmon Sharon , Metzger Dennis W 
Published: June 2021

Individuals with selective IgA deficiency are competent in producing IgG antibodies but often suffer from recurrent respiratory infections with encapsulated bacteria. We examined the immunological basis for this hyper‐susceptibility using an IgA deficient (IgA KO) mouse model. Following i.m. vaccination, WT and IgA KO mice produced similar levels of all antibody isotypes (other than IgA) against T‐dependent antigens, including CRM197 and Influenza HA and NA. However, IgA KO mice were severely defective in producing IgG antibody against T‐independent (TI) antigens such as polysaccharides, polysaccharides conjugated to carrier proteins, although they did produce normal levels of IgM. Inoculation of IL‐12 as an adjuvant during vaccination increased IgG antibody levels in both wild‐type and IgA KO mice to the same relative degree, suggesting a quantitative rather than qualitative defect in TI antigen‐responsive cells in IgA KO mice. Indeed, flow cytometric analyses revealed that IgA KO mice contained significantly fewer peritoneal B‐1a B cells, the cell type thought to be primarily responsible for TI antibody responses. These results could explain the frequent failure of conjugate vaccines to induce protective immunity in IgA‐deficient patients. Further investigations are underway to elucidate the molecular basis for the defective class switching by IgA KO mice in response to TI antigens.RO1 AI41715
An anti‐viral immune response clears virally infected neurons from the mouse brain through cytotoxic mechanisms involving IFN‐γ, perforin, and TNFα.
Authors: Lowenstein Pedro R , Bergeron Josee , Zirger Jeffery , Barrett Robert , Liu Chunyan , Castro Maria G 
Published: June 2021

The mechanisms by which the immune system eliminates virally infected cells from the brain remain unknown. We utilized a replication‐defective adenovirus to avoid direct viral‐induced cytotoxicty. A marker gene (HSV1‐TK) expressed from the adenoviral vector was used to label, characterize and quantitate infected mouse brain cells. Upon systemic immunization against adenovirus, a CD4+ and CD8+ T cell‐dependent immune response reduced the number of infected cells by >50%. Using specific knockout mice we determined that IFNy, perforin and TNFa, were necessary for eliminating virally infected cells. To demonstrate whether the immune system eliminates transgene expression through killing of transduced cells, or functional inhibition of expression from the viral genome, we developed a method that simultaneously measures gene expression from infected cells, and the number of infected cells' genomes. Using ROSA26 mice and adenoviral vectors expressing Cre, we demonstrated that the immune system abolished expression from both the viral genome and the cellular genome. Our results suggest that CD4+ and CD8+ T cells eliminate viral gene expression from the brain through cytotoxic mechanisms involving IFN‐γ, perforin, and TNFα.This work was funded by grants from NINDS, NIH.
Herpes Simplex Virus 2 infection up‐regulates TLRs expression and activates NF‐kB in human cervical epithelial cells
Authors: Li Hui , Tan Yun , Wei Yun , Zuo Zehua , Wu Xinxing 
Published: June 2021

Toll‐like receptors (TLRs) play a crucial role in the innate immune response against microbial infections, engaging differential signaling pathways, leading to activation of T cell and therefore triggering acquired immunity. Herpes Simplex Virus type 2 (HSV‐2) is one of the most common sexually transmitted pathogen and can establish lifelong latency infection. HSV‐2 is a significant co‐factor in the transmission and acquisition of HIV‐1. To determine the effect of HSV‐2 infection on TLRs expression pattern and to investigate the TLR‐mediated innate immune reponse to HSV‐2 in human cervical cells, we infected immortalized human cervical epithelial cells (HECs) with HSV‐2 (G strain) as a model in this study. The results showed that normal HECs expressed TLR1, 2, 3, 4,5, 6,9 and HSV‐2 infection up‐regulated TLRs expression at mRNA and protein level. TLR9 was dramatically elevated at late phage 36hr post‐infection by Real‐time RT‐PCR analysis. The NF‐kB and MAP Kinase p38 were rapidly activated as early as 1hr post‐infection. Different proinflammatory cytokines and interferons were also determined during the course of HSV‐2 infection. Thus, HECs possess the ability to sensor HSV‐2 infection and activate the host innate immune response through TLRs.This work was supported by grants from the National Natural Science Foundation of China (No. 30500465) and China Wuhan Chenguang Science Foundation.
mPDCA‐1 Ag reveals a novel antigen presenting cell modulating Th2 type immune responses against influenza virus infection
Authors: Yoo Jae‐Kwang , Fish Eleanor 
Published: June 2021

Objectives:Here, we have identified a novel immune cell population expressing mPDCA‐1 Ag in lymphoid tissues, which are mPDCA1+CD11c−TcRß−B220−. Studies were conducted to investigate the in vivo function of this cell population in the context of influenza virus infection.Methods:B6 mice were infected with A/WSN/33 influenza virus by intranasal inoculation. The subsequent cellular responses of the mPDCA1+CD11c−TcRß−B220− cells were monitored by FACS‐analysis.Results:Study revealed that these cells are APCs responding to viral infection. Pulmonary infection with A/WSN/33 virus stimulated these cells to up‐regulate the surface expression of MHC‐II and co‐stimulatory molecules. Influenza virus infection induced the migration of this cell into infected lungs, spleen and DLN. In the DLN, mPDCA1+CD11c−TcRß−B220− cells presented viral antigens to CD4+ T cells. Influenza virus activated mPDCA1+CD11c−TcRß−B220− cells also produced cytokines including IL‐25, IL‐2 and IL‐4 in lungs and DLN. Notably, ex vivo studies revealed that influenza virus activated mPDCA1+CD11c−TcRß−B220− cells induced the generation of Th2 effector T cells from antigen primed CD4+ T cells in the DLN.Conclusion:These results suggest that a newly described mPDCA1+CD11c−TcRß−B220− cell population may regulate a Th2 type immune response against pulmonary influenza virus infection.
The role of CD4 T cell help in restoring function of exhausted CD8 T cells during chronic infection
Authors: Aubert Rachael D , Sarkar Surojit , Ahmed Rafi 
Published: June 2021

Exhaustion of CD8 T cell function is a hallmark of chronic viral infections. Although much advance has been made in understanding the mechanisms mediating this dysfunction, little is known about the functional role of CD4 T cell help in this process. In the current study we investigated the effect newly primed antigen specific CD4 T cells may have on CD8 T cell exhaustion and disease outcome in the murine model of chronic viral infection LCMV Clone‐13. We show that adoptive transfer of monoclonal CD4 T cells during the late stages of an ongoing chronic infection can potentially restore function of virus specific CD8 T cells and lead to reduced viral levels. Furthermore, we demonstrate that blocking the PD‐1 (Programmed Death Recptor‐1) inhibitory pathway following the CD4 T cell transfer results in a synergistic effect in terms of both functional rescue of CD8 T cells and viral control. Our data provides new evidence that delivery of CD4 T cell help during ongoing chronic infection may lead to restoration of CD8 T cell function and allow favorable disease outcome.Funding for this work is through NIH grants to R. Ahmed.
Correlates of protection efficacy induced by VACV‐specific CD8+ T cell epitopes in the murine intranasal challenge model
Authors: Moutaftsi Magdalini , Salek‐Ardakani Shahram , Croft Michael , Grey Howard , Sette Alessandro 
Published: June 2021

Vaccinia virus (VACV) was used to eradicate smallpox and is considered the gold standard of vaccines. Elucidating the immunobiology of protection will reveal vaccinology principles that can be applied to future vaccine development. The identification of 49 VACV‐specific CD8+ T cell epitopes offers a unique opportunity to systematically analyze the correlation between protective efficacy and the characteristics of T cell responses.All epitopes were tested for their ability to protect peptide‐immunized C57Bl/6 mice from lethal intranasal challenge with VACV‐WR. The epitopes varied significantly in their capacity to confer protection; 15 were 75–00% protective, 22 were 25–5% protective and 12 were less than 25% protective. Measurement of IFN‐ γ following peptide immunization demonstrated that induction of high IFN‐γ correlated with high protection efficacy, whereas low IFN‐γt confer any protection. However, for some epitopes the IFN‐γtion did not correlate with protective efficacy. Ongoing studies aim to identify the underlying mechanisms that induce protective immunity by characterizing the T cell responses elicited by epitope immunization and infection.These issues are relevant for the development of new vaccine constructs, in which inclusion of isolated antigens associated with detrimental responses could jeopardize vaccine efficacy.Grant Support: NO1‐AI40024
Recalls, Records, and “Random” error: A comparison of estimates of daily energy intake variation by commonly used dietary intake methodologies
Authors: Jahns Lisa , Sieber Jessica , Carriquiry Alicia 
Published: June 2021

Objective: To compare estimates of within‐ (WIV) and between‐(BIV) individual variance (also reported as coefficients of variation) and ratios of WIV/BIV in energy intake using different dietary intake techniques and number of days of collection.Methods: Random effects models were used to calculate WIV and BIV and estimated coefficients of variation (CVw, CVb) in energy intake using 7 day food records (7FR) (n = 105), 2 day food records (2FR) (random sample of 1 weekend, 1 weekday) from the same sample, and 2 day 24HR from NHANES 2003–04 data (n = 486) (2‐24HR) in 18–19 females (F) and males (M).Results: Overall, CVw was greatest among M (n = 220) and F (n = 266) in 2–24HR NHANES data (37.5, 33.7%, respectively) compared to 2FR (M, 31.4, F, 30.9%) and 7FR (M, 29.0, F, 31.7%). CVb was lowest in the 2FR for both M and F. Ratios of WIV/BIV was greatest among F 2FR (2.8) followed by F 7FR (1.9), M 2–24HR (1.4) M 2FR (1.4), M 7FR (1.2), and F 2–24HR (1.1).Conclusion: The larger CVw found in the NHANES data is to be expected as the FR samples were collected on a university campus with more homogeneity in eating options than those available to the NHANES population. The relationship between energy intake and overweight or other nutrition‐related non‐communicable diseases may be difficult to detect in observational studies such as these when the WIV/BIV ratio exceeds unity.
Removal of glutamate from the diet enhanced postprandial leucine oxidation in the gut: evidence for nutritional significance of dietary glutamate to spare dietary leucine
Authors: Sakai Ryosei , Kuwahara Tomomi , Kawamata Yasuko , Kodama Riho , Yoneda Junya , Torii Kunio 
Published: June 2021

Glutamate (Glu), one of the most abundant amino acids in food proteins, plays crucial roles in the gut as major energy source and so on. Recently, we found that postprandial net‐release of branched chain amino acids (BCAAs) from the gut decreased in rats fed Glu‐free diet. Therefore, the present study aimed to clarify roles of dietary Glu on BCAA metabolism using [1‐13C]leucine (Leu).Amino acid defined diet containing 4% Glu (control diet) in accordance with NRC recommendation and diet in which all Glu was replaced with cornstarch (Glu‐free diet) were prepared using [1‐13C]Leu. Fisher strain male rats aged at 9 wks were given control or Glu‐free diets (2g/rat) after 12h fasting. Postprandial breath samples were collected for 7h to monitor 13CO2 production, and arterial and portal blood were collected 1, 2, 3 and 9h after the meal to measure concentrations of 13CO2 and [1‐13C]Leu.Postprandial net release of 13CO2 in expired air increased in rats fed Glu‐free diet by 20%. This increase was accompanied with the increase in portal 13CO2 appearance. Portal‐arterial differences in plasma [1‐13C]Leu concentration indicated decrease in postprandial release of ingested Leu from the gut in rats fed Glu‐free diet. These results suggest that dietary Glu substantially increases availability of ingested Leu for whole body by reducing its oxidation in the Gut. This is the first evidence suggesting sparing of Leu by dietary Glu.
Impairment of skin wound healing in mice fed with glutamate free diets: evidences for nutritional significance of dietary glutamate
Authors: Yoneda Junya , Kawamata Yasuko , Chin Keigi , Torii Kunio , Sakai Ryosei 
Published: June 2021

Background:Glutamate is one of the most abundant amino acids in food proteins. It has been shown that dietary glutamate plays crucial role as source of intestinal energy and so on, however, nutritional significance of dietary glutamate for whole body is not recognized well, because dietary glutamate is exclusively metabolized in the gut.Objective:The aim of this study is to investigate the nutritional significance of dietary glutamate in the whole body by using wound model miceMethod:Male Balb/c mice (6–0 weeks) were fed either control or glutamate‐free diets for 16 days. Seven days after the start of feeding, the mice were inserted 2 sponges into individual subcutaneous pockets and sacrificed 9 days after the operation.Results:Mice fed glutamate‐free diets displayed delayed cutaneous wound healing compared with mice fed control diet, which was recovered by ingestion of 2% monosodium glutamate (MSG) in tapping water. The delay was characterized by decrease in cytokine levels, lymphocyte recruitment to the wound site, and granulation. The delay of healing was associated with decreased local and systemic concentration of essential amino acids, such as BCAA and Phenylalanine.Conclusion:These results suggested that dietary glutamate substantially contributes to the promotion of normal wound healing presumably by maintaining certain amino acid levels in the body.
Arginine is synthesized from proline not glutamate in enterally fed preterm human infants
Authors: Tomlinson Christopher , Rafii Mahroukh , Sgro Michael , Ball Ron , Pencharz Paul 
Published: June 2021

Our laboratory recently showed in piglets that proline was the only precursor for de novo synthesis of arginine although in vitro evidence supported glutamate in this role. We performed a multitracer stable isotope study to investigate the immediate precursor for arginine in human neonates. Primed, and intermittent infusion of labeled arginine (M+2), proline (M+1) and glutamate (M+3) were given enterally to four stable, growing preterm infants at 2 weeks of age. Plasma was sampled at 8 and 12 hours during the feeding protocol with urine samples providing the baseline enrichment. The conversion of these amino acids to arginine was measured by LC‐Tandem MS to determine the contribution of each to arginine synthesis.Plateau enrichment of arginine and proline tracers was measured in plasma. Plasma glutamate enrichment was negligible. Significant conversion from proline to arginine was detected. However, the M+3 isotopomer of arginine, which would have been synthesized from glutamate, was not detected. We conclude that, like the piglet, the human neonate only synthesizes arginine from proline, and glutamate is not an arginine precursor in vivo. CIHR supported.
Tracing of glycine carbons in healthy men and women using primed, constant infusion of [1‐13C1]glycine or [1,2‐13C2]glycine and [2H3]leucine
Authors: Lamers Yvonne , Williamson Jerry , Gilbert Lesa R. , Keeling Christine , Stacpoole Peter W. , Gregory Jesse F. 
Published: June 2021

Glycine undergoes decarboxylation in the glycine cleavage system (GCS) to yield CO2, NH3, and a one‐carbon unit. CO2 also can be generated from the 2‐carbon of glycine by 10‐formyltetrahydrofolate‐dehydrogenase and, after glycine‐to‐serine conversion by serine hydroxymethyltransferase (SHMT), from the TCA cycle.To evaluate the relative fates of glycine carbons in CO2 generation in healthy volunteers (3 male, 3 female; aged 21–26y), primed, constant infusions were conducted using 9.26 μmol/(kg*h) of [1,2‐13C2]glycine and 1.87 μmol/(kg*h) of [5,5,5‐2H3]leucine, followed by an infusion protocol using [1–13C1]glycine as the glycine tracer.The rate of serine synthesis via SHMT was 186 ± 10 μmol/(kg*h) (mean ± SEM) after infusion of [1‐13C1]glycine and 185 ± 18 μmol/(kg*h) after infusion of [1,2‐13C2]glycine. Using the [1‐13C1]glycine tracer, breath CO2 data showed a glycine decarboxylation rate of 96 ± 3 μmol/(kg*h), which indicated that GCS accounted for 22 ± 1% of whole body glycine flux. Infusion of [1,2‐13C2]glycine yielded a glycine‐to‐CO2 flux of 146 ± 15 μmol/(kg*h). By difference, this implies a rate of CO2 formation from the glycine 2‐carbon of 51 ± 16 μmol/(kg*h), which accounts for ~35% of the CO2 generated in glycine catabolism. The results from the [1‐13C1]glycine tracer indicate an equally high rate (~96 μmol/(kg*h)) of production of one‐carbon units by the GCS.Supported by NIH grant DK072398 and GCRC grant M01‐RR00082
Isonitrogenous protein sources with different leucine contents differentially effect translation initiation and protein synthesis in skeletal muscle
Authors: Norton Layne Eiseman , Rupassar Indu , Layman Donald K. , Garlick Peter J. 
Published: June 2021

Leucine has been shown to stimulate phosphorylation of the initiation factors 4E‐BP1 and p70S6K (S6K) and activate skeletal muscle protein synthesis (MPS) in a dose‐dependant response (J. Nutr. 135:376–382, 2005). It is unclear if protein sources with different levels of leucine will produce the same response. This study examined 3 levels of protein intake (10%, 20% and 30% of energy) from 2 sources (whey vs wheat) that differ in leucine content (~13% vs. ~7%) on the potential to activate translation factors and MPS. Male rats (250g) were trained for 5d to eat 3 meals/d consisting of 14/56/30% calories from protein, carbohydrates and fats. Rats were sacrificed on experiment day 90 min after consuming one of the meals or fasted. Measurements include plasma insulin and amino acids, MPS via D5‐Phe incooperation, and phosphorylation of translation factors 4E‐BP1 and S6K. Whey ingestion caused a significantly greater phosphorylation of S6K and 4E‐BP1 than wheat in 10% and 20% protein groups, with no difference between the two at 30%. MPS followed a similar pattern. Phosphorylation of the translation factors and MPS were similar for 10% whey and 20% wheat and similar for 20% whey and 30% wheat. These findings are consistent with the role of leucine as a regulatory substrate for MPS and suggest that leucine content of protein sources is a major determinant of protein quality for maximizing MPS.Support: National Dairy Council
p63 Induces Key Target Genes Required for Epidermal Morphogenesis
Authors: Koster Maranke , Dai Daisy , Marinari Barbara , Costanzo Antonio , Karin Michael , Roop Dennis 
Published: June 2021

Epidermal morphogenesis is controlled by p63, a transcription factor that can be expressed as multiple isoforms. Of these, ΔNp63 isoforms are the predominantly expressed isoforms in late embryonic and postnatal epidermis. To determine the role of ΔNp63 proteins, we generated an epidermal‐specific inducible ΔNp63 knockdown mouse model. We found that downregulating ΔNp63 expression caused severe epidermal defects, including aberrant keratinocyte differentiation and impaired basement membrane formation, culminating in the development of severe skin erosions. Interestingly, these lesions were indistinguishable from lesions that develop in patients with AEC, a skin fragility disorder caused by mutations in ΔNp63α. We found that, during epidermal morphogenesis, ΔNp63α initially induces expression of Fras1, which is required for maintaining the integrity of the epidermal‐dermal interface at the basement membrane. Subsequently, ΔNp63α initiates epidermal terminal differentiation by inducing IKKα. Together, our data provide novel insights into the role of ΔNp63α in epidermal morphogenesis and homeostasis, and may contribute to our understanding of the pathogenic mechanisms underlying disorders caused by p63 mutations.This work was supported by grants from the NIH and the National Foundation for Ectodermal Dysplasias.