Although B cells expressing the IFNgR or the IFNg-inducible transcription factor T-bet drive autoimmunity in Systemic Lupus Erythematosus (SLE)-prone mouse models, the role for IFNg signaling in human antibody responses is unknown. We show that elevated levels of IFNg in SLE patients correlate with expansion of the T-bet expressing IgDnegCD27negCD11c+CXCR5neg (DN2) pre-antibody secreting cell (pre-ASC) subset. We demonstrate that naïve B cells form T-bethi pre-ASCs following stimulation with either Th1 cells or with IFNg, IL-2, anti-Ig and TLR7/8 ligand and that IL-21 dependent ASC formation is significantly enhanced by IFNg or IFNg-producing T cells. IFNg promotes ASC development by synergizing with IL-2 and TLR7/8 ligands to induce genome-wide epigenetic reprogramming of B cells, which results in increased chromatin accessibility surrounding IRF4 and BLIMP1 binding motifs and epigenetic remodeling of IL21R and PRDM1 loci. Finally, we show that IFNg signals poise B cells to differentiate by increasing their responsiveness to IL-21.
Sequencing data have been deposited in GEO under accession codes GSE95282 and GSE118984. All data generated or analyzed during this study are included in the manuscript and supporting files. Source data files for sequencing analysis are included as Supplementary Files 1 and 2 (excel files).
Chromatin accessibility of ex vivo derived Be-g2 cellsNCBI Gene Expression Omnibus, GSE119726.
Be1 and Be2 B cells are transcriptionally distinctNCBI Gene Expression Omnibus, GSE95282.
Gene expression studies of lupus and healthy B cell subsets through RNA sequencingNCBI Gene Expression Omnibus, GSE92387.
Molecular Signatures Database (MSigDB)Molecular Signatures Database.
- Travis Ptacek
- Trenton R Schoeb
- Frances E Lund
- Frances E Lund
- Jeremy Boss
- Jeremy M Boss
- Sanz Inaki
- Sanz Inaki
- Sara L Stone
- Maria I Danila
- Frances E Lund
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Animal experimentation: All procedures involving animals were approved by the UAB Institutional Animal Care and Use Committee and were conducted in accordance with the principles outlined by the National Research Council. UAB IACUC approval IACUC-09648 and IACUC-21203.
Human subjects: All subjects gave written informed consent for participation and provided peripheral blood for analysis. The UAB and Emory Human Subjects Institutional Review Board approved all study protocols for healthy donors and SLE patients. IRB protocols 160301002, X020805006, X140213002, and N140102003 for UAB and 58515 for Emory.
- Facundo D Batista, Ragon Institute of MGH, MIT and Harvard, United States
© 2019, Zumaquero et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
Age-associated DNA methylation in blood cells convey information on health status. However, the mechanisms that drive these changes in circulating cells and their relationships to gene regulation are unknown. We identified age-associated DNA methylation sites in six purified blood-borne immune cell types (naive B, naive CD4+ and CD8+ T cells, granulocytes, monocytes, and NK cells) collected from healthy individuals interspersed over a wide age range. Of the thousands of age-associated sites, only 350 sites were differentially methylated in the same direction in all cell types and validated in an independent longitudinal cohort. Genes close to age-associated hypomethylated sites were enriched for collagen biosynthesis and complement cascade pathways, while genes close to hypermethylated sites mapped to neuronal pathways. In silico analyses showed that in most cell types, the age-associated hypo- and hypermethylated sites were enriched for ARNT (HIF1β) and REST transcription factor (TF) motifs, respectively, which are both master regulators of hypoxia response. To conclude, despite spatial heterogeneity, there is a commonality in the putative regulatory role with respect to TF motifs and histone modifications at and around these sites. These features suggest that DNA methylation changes in healthy aging may be adaptive responses to fluctuations of oxygen availability.
Infection with Influenza A virus (IAV) causes the well-known symptoms of the flu, including fever, loss of appetite, and excessive sleepiness. These responses, mediated by the brain, will normally disappear once the virus is cleared from the system, but a severe respiratory virus infection may cause long-lasting neurological disturbances. These include encephalitis lethargica and narcolepsy. The mechanisms behind such long lasting changes are unknown. The hypothalamus is a central regulator of the homeostatic response during a viral challenge. To gain insight into the neuronal and non-neuronal molecular changes during an IAV infection, we intranasally infected mice with an H1N1 virus and extracted the brain at different time points. Using single-nucleus RNA sequencing (snRNA-seq) of the hypothalamus, we identify transcriptional effects in all identified cell populations. The snRNA-seq data showed the most pronounced transcriptional response at 3 days past infection, with a strong downregulation of genes across all cell types. General immune processes were mainly impacted in microglia, the brain resident immune cells, where we found increased numbers of cells expressing pro-inflammatory gene networks. In addition, we found that most neuronal cell populations downregulated genes contributing to the energy homeostasis in mitochondria and protein translation in the cytosol, indicating potential reduced cellular and neuronal activity. This might be a preventive mechanism in neuronal cells to avoid intracellular viral replication and attack by phagocytosing cells. The change of microglia gene activity suggest that this is complemented by a shift in microglia activity to provide increased surveillance of their surroundings.