In the maternal decidua, natural killer (NK) cells, characterized by lack of CD16, are found in direct contact with the fetal extravillous trophoblasts (EVTs). It is yet unknown which factors contribute to the specific homing of this unique NK subset to the decidua. In this study we analyze the chemokine receptor repertoire on various NK populations derived from the peripheral blood and decidua. We show that CXCR4 and CXCR3 receptors are preferentially expressed on CD16 ؊ NK subsets derived either from the peripheral blood or the decidua and that these receptors are involved in migration of all NK subsets to their ligands. We further demonstrate in vivo that invading EVTs that eventually perform endovascular invasion express CXCL12, the ligand for CXCR4, but not ligands for CXCR3. Indeed, specific accumulation of the CD16 ؊ NK cells at the expense of CD16 ؉ cells was observed only when in vitro migration was performed with ligands for CXCR4. Finally, incubation of the peripheral blood CD16 ؊ NK cells with cytokines present in the decidua, especially interleukin 15 (IL-15), resulted in the expression of chemokine receptor repertoire similar to that observed on decidual NK cells, suggesting an additional important regulatory effect of local decidual cytokines.

DNA methylation is a fundamental epigenetic mark that governs gene expression and chromatin organization, thus providing a window into cellular identity and developmental processes1. Current datasets typically include only a fraction of methylation sites and are often based either on cell lines that underwent massive changes in culture or on tissues containing unspecified mixtures of cells2–5. Here we describe a human methylome atlas, based on deep whole-genome bisulfite sequencing, allowing fragment-level analysis across thousands of unique markers for 39 cell types sorted from 205 healthy tissue samples. Replicates of the same cell type are more than 99.5% identical, demonstrating the robustness of cell identity programmes to environmental perturbation. Unsupervised clustering of the atlas recapitulates key elements of tissue ontogeny and identifies methylation patterns retained since embryonic development. Loci uniquely unmethylated in an individual cell type often reside in transcriptional enhancers and contain DNA binding sites for tissue-specific transcriptional regulators. Uniquely hypermethylated loci are rare and are enriched for CpG islands, Polycomb targets and CTCF binding sites, suggesting a new role in shaping cell-type-specific chromatin looping. The atlas provides an essential resource for study of gene regulation and disease-associated genetic variants, and a wealth of potential tissue-specific biomarkers for use in liquid biopsies.

H epatic fibrosis associated with inflammatory cell infiltration is a prominent feature of persistent infection by hepatitis B virus (HBV) and hepatitis C virus (HCV). The hepatic stellate cell (HSC) has assumed a central role in this response after its activation by inflammatory cytokines and mediators. [1][2][3][4][5] The cellmediated immune response after viral hepatitis reflects the activity of CD4ϩ helper T and CD8ϩ cytotoxic T

Chronic hepatitis C virus (HCV) and hepatitis B virus (HBV) infection is accompanied by inflammation and fibrosis eventually leading to cirrhosis. The chemokine CXCL12 is involved in chronic inflammatory conditions. The role of the CXCL12/CXCR4 pathway in HCV-and HBV-associated liver inflammation and fibrosis was therefore studied. The levels and tissue localization of CXCL12 in liver and plasma of HCV and HBV patients were tested using immunohistochemistry and ELISA. The expression and function of CXCR4 on liver-infiltrating lymphocytes (LIL) were tested by FACS and transwell migration assays. We found that CXCL12 is expressed by bile duct epithelial cells in normal liver tissue. Bile duct proliferation and liver fibrosis in chronic HCV and HBV infection result in the anatomical re-distribution of CXCL12 in the liver. Moreover, CXCL12 is up-regulated in the endothelium of neo-bloodvessels formed in active inflammatory foci and is significantly elevated, compared with controls, in the plasma of patients with advanced liver fibrosis. Complementing these observations were others indicating that over 50% of LIL express CXCR4 and, in response to CXCL12, migrated and adhered to fibronectin. These observations suggest an important role for the CXCL12/CXCR4 pathway in recruitment and retention of immune cells in the liver during chronic HCV and HBV infection.