Apolipoprotein E controls Dectin-1-dependent development of monocyte-derived alveolar macrophages upon pulmonary ß-glucan-induced inflammatory adaptation.

The lung is constantly exposed to the outside world and optimal adaptation of immune responses is crucial for efficient pathogen clearance. However, mechanisms that lead to lung-associated macrophages' functional and developmental adaptation remain elusive. To reveal such mechanisms, we developed a reductionist model of environmental intranasal ß-glucan exposure, allowing for the detailed interrogation of molecular mechanisms of pulmonary macrophage adaptation. Employing single-cell transcriptomics, high-dimensional imaging and flow cytometric characterization paired with in vivo and ex vivo challenge models, we reveal that pulmonary low-grade inflammation results in the development of apolipoprotein E (ApoE)-dependent monocyte-derived alveolar macrophages (ApoE+CD11b+ AMs). ApoE+CD11b+ AMs expressed high levels of CD11b, ApoE, Gpnmb and Ccl6, were glycolytic, highly phagocytic and produced large amounts of interleukin-6 upon restimulation. Functional differences were cell intrinsic, and myeloid cell-specific ApoE ablation inhibited Ly6c+ monocyte to ApoE+CD11b+ AM differentiation dependent on macrophage colony-stimulating factor secretion, promoting ApoE+CD11b+ AM cell death and thus impeding ApoE+CD11b+ AM maintenance. In vivo, ß-glucan-elicited ApoE+CD11b+ AMs limited the bacterial burden of Legionella pneumophilia after infection and improved the disease outcome in vivo and ex vivo in a murine lung fibrosis model. Collectively these data identify ApoE+CD11b+ AMs generated upon environmental cues, under the control of ApoE signaling, as an essential determinant for lung adaptation enhancing tissue resilience.

Multiplex peptide-MHC tetramer staining using mass cytometry for deep analysis of the influenza-specific T-cell response in mice.

Antigen-specific T cells play a crucial role for the host protective immunity against viruses and other diseases. The use of mass cytometry together with a combinatorial multiplex tetramer staining has successfully been applied for probing and characterization of multiple antigen-specific CD8+ T cells in human blood samples. The present study shows that this approach can also be used to rapidly assess the magnitude of influenza-specific CD8+ T cell epitope dominance across lymph nodes and lungs in a murine model of a highly pathological influenza infection. Moreover, we show feasibility of extending this approach to include concurrent identification of virus-specific CD4+ T cells. By using a double coding approach, we probed for five influenza-specific MHCI-peptide complexes as well as one influenza-specific MHCII-peptide complex in the presence of irrelevant control peptides and show that this approach is capable of tracking antigen-specific T cells across individual lymph nodes and lungs. The simultaneous staining with 26 surface maker molecules further facilitated an in-depth characterization of T cells reacting with influenza epitopes and revealed tissue specific phenotypic differences between CD4+ T cells targeting the same pathogenic epitope. In conclusion, this approach provides the possibility for a rapid and comprehensive analysis of antigen-specific CD8+ and CD4+ T cells in different disease settings that might be advantageous for subsequent vaccine formulation strategies.

Morphine treatment affects the regulation of high mobility group I-type chromosomal phosphoproteins in C6 glioma cells.

High mobility group (HMG) I-type chromosomal phosphoproteins HMG I/Y and HMG I-C were investigated following morphine treatment of C6BU-1 glioma. Cells were labelled with [32P]-orthophosphoric acid. Electrophoretic profiles and autoradiograms of the control cells revealed the presence of HMG I and HMG I-C proteins. HMG Y was not detected. Northern blot analysis showed a single HMG I/Y transcript. Treatment with morphine lowered the [32P]-incorporation in HMG I and HMGI-C proteins and the level of the HMG I/Y transcript. However, it did not change the protein ratios on the Coomassie stained gels. These results suggest that morphine may trigger independent reaction pathways affecting either transcription regulation and/or postsynthetic phosphorylation of the preexisting HMG I-type proteins. In addition, opposing changes in the postsynthetic phosphorylation of HMG 14 and histones H1AB were also noticed.

Repair pattern in the beta-globin gene cluster of human fibroblasts after ultraviolet irradiation.

We have developed a novel technique to determine repair of structurally different DNA lesions. It was used to address the question of whether DNA repair in the absence of transcription occurs in a uniformly random manner or with preferences for certain regions. Human fibroblasts were exposed to ultraviolet light (3-10 J/m2) and treated with 7.5 mM hydroxyurea to inhibit replicative DNA synthesis. During the first hours after irradiation cells were treated with 5-bromodeoxyuridine to label the regions undergoing repair, with the presumption that the regions that have been more efficiently repaired would incorporate more of the nucleoside. A 155-kb DNA sequence containing the entire human beta-globin domain was reconstructed using sequences deposited in the EMBL gene bank. Twelve uniformly long single-copy RNA probes spanning the beta-globin cluster were synthesised in vitro and immobilized on microtiter plates. They were hybridized with DNA from the irradiated cells. The amount of 5-bromodeoxyuridine, incorporated as a result of repair in the DNA fractions hybridized to the different RNA probes, was determined immunochemically using antibody to this nucleoside. By this technique we registered increased repair efficiency in the zone of the permanent scaffold attachment region at the 5'-end of the beta-globin domain during the first hours after ultraviolet irradiation. This result was confirmed and by the more conventional T4 endonuclease V technique detecting the removal of cyclobutane pyrimidine dimers.