by
June E. Pais;
Nan Dai;
Esta Tamanaha;
Romualdas Vaisvila;
Alexey I. Fomenkov;
Jurate Bitinaite;
Zhiyi Sun;
Shengxi Guan;
Ivan Correa;
Christopher J. Noren;
Xiaodong Cheng;
Richard J. Roberts;
Yu Zheng;
Lana Saleh
Modified DNA bases in mammalian genomes, such as 5-methylcytosine (<sup>5m</sup>C) and its oxidized forms, are implicated in important epigenetic regulation processes. In human or mouse, successive enzymatic conversion of <sup>5m</sup>C to its oxidized forms is carried out by the ten-eleven translocation (TET) proteins. Previously we reported the structure of a TET-like <sup>5m</sup>C oxygenase (NgTET1) from Naegleria gruberi, a single-celled protist evolutionarily distant from vertebrates. Here we show that NgTET1 is a 5-methylpyrimidine oxygenase, with activity on both <sup>5m</sup>C (major activity) and thymidine (T) (minor activity) in all DNA forms tested, and provide unprecedented evidence for the formation of 5-formyluridine (<sup>5f</sup>U) and 5-carboxyuridine (<sup>5ca</sup>U) in vitro. Mutagenesis studies reveal a delicate balance between choice of <sup>5m</sup>C or T as the preferred substrate. Furthermore, our results suggest substrate preference by NgTET1 to <sup>5m</sup>CpG and TpG dinucleotide sites in DNA. Intriguingly, NgTET1 displays higher T-oxidation activity in vitro than mammalian TET1, supporting a closer evolutionary relationship between NgTET1 and the base J-binding proteins from trypanosomes. Finally, we demonstrate that NgTET1 can be readily used as a tool in <sup>5m</sup>C sequencing technologies such as single molecule, realtime sequencing to map <sup>5m</sup>C in bacterial genomes at base resolution.
by
Pablo Penaloza-MacMaster;
Daniel L. Barber;
E. John Wherry;
Nicholas M. Provine;
Jeffrey E. Teigler;
Lily Parenteau;
Stephen Blackmore;
Erica N. Borducchi;
Rafael A. Larocca;
Kathleen B. Yates;
Hao Shen;
W. Nicholas Haining;
Rami Sommerstein;
Daniel D. Pinschewer;
Rafi Ahmed;
Dan. H. Barouch
CD4 T cells promote innate and adaptive immune responses, but how vaccine-elicited CD4 T cells contribute to immune protection remains unclear. We evaluated whether induction of virus-specific CD4 T cells by vaccination would protect mice against infection with chronic lymphocytic choriomeningitis virus (LCMV). Immunization with vaccines that selectively induced CD4 T cell responses resulted in catastrophic inflammation and mortality after challenge with a persistent strain of LCMV. Immunopathology required antigen-specific CD4 T cells and was associated with a cytokine storm, generalized inflammation, and multi-organ system failure. Virus-specific CD8 T cells or antibodies abrogated the pathology. These data demonstrate that vaccine-elicited CD4 T cells in the absence of effective antiviral immune responses can trigger lethal immunopathology.
Fragile X syndrome (FXS) results in intellectual disability (ID) most often caused by silencing of the fragile X mental retardation 1 (FMR1) gene. The resulting absence of fragile X mental retardation protein 1 (FMRP) leads to both pre- and postsynaptic defects, yet whether the pre- and postsynaptic functions of FMRP are independent and have distinct roles in FXS neuropathology remain poorly understood. Here, we demonstrate an independent presynaptic function for FMRP through the study of an ID patient with an FMR1 missense mutation. This mutation, c.413G > A (R138Q), preserves FMRP's canonical functions in RNA binding and translational regulation, which are traditionally associated with postsynaptic compartments. However, neuronally driven expression of the mutant FMRP is unable to rescue structural defects at the neuromuscular junction in fragile x mental retardation 1 (dfmr1)-deficient Drosophila, suggesting a presynaptic-specific impairment. Furthermore, mutant FMRP loses the ability to rescue presynaptic action potential (AP) broadening in Fmr1 KO mice. The R138Q mutation also disrupts FMRP's interactionwith the large-conductance calciumactivated potassium (BK) channels that modulate AP width. These results reveal a presynaptic- and translation-independent function of FMRP that is linked to a specific subset of FXS phenotypes.
by
Lu Xu;
Hongyu Guo;
Christopher M. Boyd;
Mitchel Klein;
Aikaterini Bougiatioti;
Kate M. Cerully;
James R. Hite;
Gabriel Isaacman-VanWertz;
Nathan M. Kreisberg;
Christoph Knote;
Kevin Olson;
Abigail Koss;
Allen H. Goldstein;
Susanne V. Hering;
Joost de Gouw;
Karsten Baumann;
Shan-Hu Lee;
Athanasios Nenes;
Rodney J. Weber;
Nga Lee Ng
Secondary organic aerosol (SOA) constitutes a substantial fraction of fine particulate matter and has important impacts on climate and human health. The extent to which human activities alter SOA formation from biogenic emissions in the atmosphere is largely undetermined. Here, we present direct observational evidence on the magnitude of anthropogenic influence on biogenic SOA formation based on comprehensive ambient measurements in the southeastern United States (US). Multiple high-time-resolution mass spectrometry organic aerosol measurements were made during different seasons at various locations, including urban and rural sites in the greater Atlanta area and Centreville in rural Alabama. Our results provide a quantitative understanding of the roles of anthropogenic SO2 and NOx in ambient SOA formation. We show that isoprene-derived SOA is directly mediated by the abundance of sulfate, instead of the particle water content and/or particle acidity as suggested by prior laboratory studies. Anthropogenic NOx is shown to enhance nighttime SOA formation via nitrate radical oxidation of monoterpenes, resulting in the formation of condensable organic nitrates. Together, anthropogenic sulfate and NOx can mediate 43-70% of total measured organic aerosol (29-49% of submicron particulate matter, PM1) in the southeastern US during summer. These measurements imply that future reduction in SO2 and NOx emissions can considerably reduce the SOA burden in the southeastern US. Updating current modeling frameworks with these observational constraints will also lead to more accurate treatment of aerosol formation for regions with substantial anthropogenic-biogenic interactions and consequently improve air quality and climate simulations.
Couples HIV Testing and Counseling (CHTC) has been used as an HIV prevention strategy in Africa for over 20 years where the HIV epidemic is largely concentrated among sexually active heterosexuals. In recent years, CHTC has been adapted for men who have sex with men (MSM) in the US. A central element of the CHTC intervention as adapted for male couples in the US is the discussion of sexual agreements by the dyad during the CHTC session. Given the success of CHTC for heterosexual couples in Africa, it seems appropriate that CHTC could also be provided to heterosexual couples in the US. However, little is known about heterosexual’s willingness to utilize CHTC services including discussion of sexual agreements. This small, preliminary qualitative study sheds new light on the potential for CHTC adoption among heterosexuals in the US. Four focus groups were conducted with heterosexual men and women attending a publicly-funded STI clinic, to explore the potential feasibility and acceptability of CHTC with heterosexuals. The results are similar to those seen for MSM: high levels of willingness to use CHTC, perceptions of the advantages of using CHTC, and willingness to discuss sexual agreements; all necessary conditions for the successful roll-out of CHTC. Further work is now needed with larger samples of high-risk heterosexuals to more completely understand the typologies of sexual agreements and the common language used for sexual agreements in heterosexual relationships. These early data show great promise that CHTC can achieve the same levels of willingness, fit, and acceptability among heterosexual couples as currently experienced by male couples in the US.
CD8 T cells are a potent tool for eliminating intracellular pathogens and tumor cells. Thus, eliciting robust CD8 T-cell immunity is the basis for many vaccines under development. However, the relationship between antigen load and the magnitude of the CD8 T-cell response is not well-described in a human immune response. Here we address this issue by quantifying viral load and the CD8 T-cell response in a cohort of 80 individuals immunized with the live attenuated yellow fever vaccine (YFV-17D) by sampling peripheral blood at days 0, 1, 2, 3, 5, 7, 9, 11, 14, 30, and 90.
When the virus load was below a threshold (peak virus load < 225 genomes per mL, or integrated virus load < 400 genome days per mL), the magnitude of the CD8 T-cell response correlated strongly with the virus load (R2 ∼ 0.63). As the virus load increased above this threshold, the magnitude of the CD8 T-cell responses saturated. Recent advances in CD8 T-cell-based vaccines have focused on replication-incompetent or single-cycle vectors. However, these approaches deliver relatively limited amounts of antigen after immunization. Our results highlight the requirement that T-cell-based vaccines should deliver sufficient antigen during the initial period of the immune response to elicit a large number of CD8 T cells that may be needed for protection.
by
Kaval Kaur;
Nai-Ying Zheng;
Kenneth Smith;
Min Huang;
Lie Li;
Noel T. Pauli;
Carole J. Henry Dunand;
Jane-Hwei Lee;
Michael Morrissey;
Yixuan Wu;
Michelle L. Joachims;
Melissa E. Munroe;
Denise Lau;
Xinyan Qu;
Florian Krammer;
Jens Wrammert;
Peter Palese;
Rafi Ahmed;
Judith A. James;
Patrick C. Wilson
Breakdown of B cell tolerance is a cardinal feature of systemic lupus erythematosus (SLE). Increased numbers of autoreactive mature naïve B cells have been described in SLE patients and autoantibodies have been shown to arise from autoreactive and non-autoreactive precursors. How these defects, in the regulation of B cell tolerance and selection, influence germinal center (GC) reactions that are directed towards foreign antigens has yet to be investigated. Here, we examined the characteristics of post-GC foreign antigen-specific B cells from SLE patients and healthy controls by analyzing monoclonal antibodies generated from plasmablasts induced specifically by influenza vaccination. We report that many of the SLE patients had anti-influenza antibodies with higher binding affinity and neutralization capacity than those from controls. Although overall frequencies of autoreactivity in the influenza-specific plasmablasts were similar for SLE patients and controls, the variable gene repertoire of influenza-specific plasmablasts from SLE patients was altered, with increased usage of JH6 and long heavy chain CDR3 segments. We found that high affinity anti-influenza antibodies generally characterize the plasmablast responses of SLE patients with low levels of autoreactivity; however, certain exceptions were noted. The high-avidity antibody responses in SLE patients may also be correlated with cytokines that are abnormally expressed in lupus. These findings provide insights into the effects of dysregulated immunity on the quality of antibody responses following influenza vaccination and further our understanding of the underlying abnormalities of lupus.
False discovery rate (FDR) control is an important tool of statistical inference in feature selection. In mass spectrometry-based metabolomics data, features can be measured at different levels of reliability and false features are often detected in untargeted metabolite profiling as chemical and/or bioinformatics noise. The traditional false discovery rate methods treat all features equally, which can cause substantial loss of statistical power to detect differentially expressed features. We propose a reliability index for mass spectrometry-based metabolomics data with repeated measurements, which is quantified using a composite measure. We then present a new method to estimate the local false discovery rate (lfdr) that incorporates feature reliability. In simulations, our proposed method achieved better balance between sensitivity and controlling false discovery, as compared to traditional lfdr estimation. We applied our method to a real metabolomics dataset and were able to detect more differentially expressed metabolites that were biologically meaningful.
Disease incidences increase with age, but the molecular characteristics of ageing that lead to increased disease susceptibility remain inadequately understood. Here we perform a whole-blood gene expression meta-analysis in 14,983 individuals of European ancestry (including replication) and identify 1,497 genes that are differentially expressed with chronological age. The age-associated genes do not harbor more age-associated CpG-methylation sites than other genes, but are instead enriched for the presence of potentially functional CpG-methylation sites in enhancer and insulator regions that associate with both chronological age and gene expression levels. We further used the gene expression profiles to calculate the 'transcriptomic age' of an individual, and show that differences between transcriptomic age and chronological age are associated with biological features linked to ageing, such as blood pressure, cholesterol levels, fasting glucose, and body mass index. The transcriptomic prediction model adds biological relevance and complements existing epigenetic prediction models, and can be used by others to calculate transcriptomic age in external cohorts.
Background and Purpose: Diffusion-weighted imaging (DWI) and perfusion MRI were used to examine the spatiotemporal evolution of stroke lesions in adult macaques with ischemic occlusion. Methods: Permanent MCA occlusion was induced with silk sutures through an interventional approach via the femoral artery in adult rhesus monkeys (n = 8, 10-21 years old). The stroke lesions were examined with high-resolution DWI and perfusion MRI, and T2-weighted imaging (T2W) on a clinical 3T scanner at 1-6, 48, and 96 hours post occlusion and validated with H&E staining. Results: The stroke infarct evolved via a natural logarithmic pattern with the mean infarct growth rate = 1.38 ± 1.32 ml per logarithmic time scale (hours) (n = 7) in the hyperacute phase (1-6 hours). The mean infarct volume after 6 hours post occlusion was 3.6±2.8 ml (n = 7, by DWI) and increased to 3.9±2.9 ml (n = 5, by T2W) after 48 hours, and to 4.7±2.2ml (n = 3, by T2W) after 96 hours post occlusion. The infarct volumes predicted by the natural logarithmic function were correlated significantly with the T2W-derived lesion volumes (n = 5, r = 0.92, p = 0.01) at 48 hours post occlusion. The final infarct volumes derived from T2W were correlated significantly with those from H&E staining (r = 0.999, p < 0.0001, n = 4). In addition, the diffusion-perfusion mismatch was visible generally at 6 hours but nearly diminished at 48 hours post occlusion. Conclusion: The infarct evolution follows a natural logarithmic pattern in the hyperacute phase of stroke. The logarithmic pattern of evolution could last up to 48 hours after stroke onset and may be used to predict the infarct volume growth during the acute phase of ischemic stroke. The nonhuman primate model, MRI protocols, and post data processing strategy may provide an excellent platform for characterizing the evolution of acute stroke lesion in mechanistic studies and therapeutic interventions of stroke disease.