Single-cell fate mapping reveals widespread clonal ignorance of low-affinity T cells exposed to systemic infection

T cell ignorance is a specific form of immunological tolerance. It describes the maintenance of naivety in antigen-specific T cells in vivo despite the presence of their target antigen. It is thought to mainly play a role during the steady state, when self-antigens are presented in absence of costimulatory signals and at low density or to T cells of low affinity. In how far antigen-specific T cells can also remain clonally ignorant to foreign antigens, presented in the inflammatory context of systemic infection, remains unclear. Using single-cell in vivo fate mapping and high throughput flow cytometric enrichment, we find that high-affinity antigen-specific CD8⁺ T cells are efficiently recruited upon systemic infection. In contrast, most low-affinity antigen-specific T cells ignore the priming antigen and persist in the naïve state while remaining fully responsive to subsequent immunization with a high-affinity ligand. These data establish the widespread clonal ignorance of low-affinity T cells as a major factor shaping the composition of antigen-specific CD8⁺ T cell responses to systemic infection.     

Focal adhesion kinase a potential therapeutic target for pancreatic cancer and malignant pleural mesothelioma

The non-receptor cytoplasmic tyrosine kinase, Focal Adhesion Kinase (FAK) is known to play a key role in a variety of normal and cancer cellular functions such as survival, proliferation, migration and invasion. It is highly active and overexpressed in various cancers including Pancreatic Ductal Adenocarcinoma (PDAC) and Malignant Pleural Mesothelioma (MPM). Here, initially, we demonstrate that FAK is overexpressed in both PDAC and MPM cell lines. Then we analyze effects of two small molecule inhibitors PF-573228, and PF-431396, which are dual specificity inhibitors of FAK and proline rich tyrosine kinase 2 (PYK2), as well as VS-6063, another small molecule inhibitor that specifically inhibits FAK but not PYK2 for cell growth, motility and invasion of PDAC and MPM cell lines. Treatment with PF-573228, PF-431396 and VS-6063 cells resulted in a dose-dependent inhibition of growth and anchorage-independent colony formation in both cancer cell lines. Furthermore, these compounds suppressed the phosphorylation of FAK at its active site, Y397, and functionally induced significant apoptosis and cell cycle arrest in both cell lines. Using the ECIS (Electric cell-substrate impedance sensing) system, we found that treatment of both PF compounds suppressed adherence and migration of PDAC cells on fibronectin. Interestingly, 3D-tumor organoids derived from autochthonous KC (Kras;PdxCre) mice treated with PF-573228 revealed a significant decrease in tumor organoid size and increase in organoid cell death. Taken together, our results show that FAK is an important target for mesothelioma and pancreatic cancer therapy that merit further translational studies.     

Shortened Telomere Length in Sputum Cells of Bronchiectasis Patients is Associated with Dysfunctional Inflammatory Pathways

Telomere attrition is an established ageing biomarker and shorter peripheral blood leukocyte telomere length has been associated with increased risks of respiratory diseases. However, whether telomere length in disease-relevant sputum immune cells of chronic respiratory disease patients is shortened and which pathways are dysfunctional are not clear. Here we measured telomere length from sputum samples of bronchiectasis and asthmatic subjects and determined that telomere length in sputum of bronchiectasis subjects was significantly shorter (Beta?=????1.167, P_Adj?=?2.75?×?10^?4). We further performed global gene expression analysis and identified genes involved in processes such as NLRP3 inflammasome activation and regulation of adaptive immune cells when bronchiectasis sputum telomere length was shortened. Our study provides insights on dysfunctions related to shortened telomere length in sputum immune cells of bronchiectasis patients.

     

Solutions to the water flooding problem for unitized regenerative fuel cells: status and perspectives

Unitized regenerative fuel cells (URFC) are capable of generating, storing, and releasing energy on demand in a sustainable manner. Water management is of vital importance to achieve maximum performance, durability, and round-trip efficiency in URFCs. However, URFCs suffer from critical issues related to their mode-switching process, water flooding, and membrane dehydration. The essential problem of water management is maintaining a subtle equilibrium between membrane drying and liquid water flooding to prevent membrane dehydration and ensure high URFC performance. This paper provides an overview of the operating principle of URFCs and describes the underlying phenomena related to water management issues. It also summarizes state-of-the-art studies of water management with a focus on recent developments and discusses the technical challenges of water management strategies. In addition, we propose a novel system design to address these critical water management issues. Overall, this review identifies the gaps in the research and development of URFC water management and identifies several essential future developments and research directions for future investigation.

This review summarizes state-of-the-art studies on water management of URFC''s with a focus on recent developments and discusses the technical challenges of water management strategies.     

Abrogation of Vif function by peptide derived from the N-terminal region of the human immunodeficiency virus type 1 (HIV-1) protease

The human immunodeficiency virus type 1 (HIV-1) auxiliary gene vif is essential for virus propagation in peripheral blood lymphocytes, macrophages, and in some T-cell lines. Previously, it was demonstrated that Vif inhibits the autoprocessing of truncated HIV-1 Gag-Pol polyproteins expressed in bacterial cells, and that purified recombinant Vif and Vif-derived peptides inhibit and bind HIV-1 protease (PR). Here we show that Vif interacts with the N-terminal region of HIV-1 PR, and demonstrate that peptide derived from the N-terminal region of PR abrogates Vif function in non-permissive cells. Specifically, we show that (i) Vif protein binds HIV-1 PR, but not covalently linked tethered PR-PR; (ii) the four amino acids residing at the N terminus of HIV-1 PR are essential for Vif/PR interaction; (iii) synthetic peptide derived from the N terminus of HIV-1 PR inhibits Vif/PR binding; and (iv) this peptide inhibits the propagation of HIV-1 in restrictive cells. Based on these data, we suggest that Vif interacts with the dimerization sites of the viral protease, and that peptide residing at the N terminus of PR abrogates Vif function(s).     

Resorption

Ohne Zusammenfassung     

Kritisches zur Stoffwechsel- und ErnÄhrungslehre

Ohne Zusammenfassung     

Effects of Epitope Modification on T Cell Receptor–Ligand Binding and Antigen Recognition by Seven H-2Kd–restricted Cytotoxic T Lymphocyte Clones Specific for a Photoreactive Peptide Derivative

We tested for antigen recognition and T cell receptor (TCR)–ligand binding 12 peptide derivative variants on seven H-2K^d–restricted cytotoxic T lymphocytes (CTL) clones specific for a bifunctional photoreactive derivative of the Plasmodium berghei circumsporozoite peptide 252– 260 (SYIPSAEKI). The derivative contained iodo-4-azidosalicylic acid in place of PbCS S-252 and 4-azidobenzoic acid on PbCS K-259. Selective photoactivation of the N-terminal photoreactive group allowed crosslinking to K^d molecules and photoactivation of the orthogonal group to TCR. TCR photoaffinity labeling with covalent K^d–peptide derivative complexes allowed direct assessment of TCR–ligand binding on living CTL. In most cases (over 80%) cytotoxicity (chromium release) and TCR–ligand binding differed by less than fivefold. The exceptions included (a) partial TCR agonists (8 cases), for which antigen recognition was fivetenfold less efficient than TCR–ligand binding, (b) TCR antagonists (2 cases), which were not recognized and capable of inhibiting recognition of the wild-type conjugate, (c) heteroclitic agonists (2 cases), for which antigen recognition was more efficient than TCR–ligand binding, and (d) one partial TCR agonist, which activated only Fas (CD95), but not perforin/granzymemediated cytotoxicity. There was no correlation between these divergences and the avidity of TCR–ligand binding, indicating that other factors than binding avidity determine the nature of the CTL response. An unexpected and novel finding was that CD8-dependent clones clearly incline more to TCR antagonism than CD8-independent ones. As there was no correlation between CD8 dependence and the avidity of TCR–ligand binding, the possibility is suggested that CD8 plays a critical role in aberrant CTL function.