17β-Estradiol promotes LC3B-associated phagocytosis in trained immunity of female mice against sepsis

Sepsis is a common serious clinical infectious disease accompanied by more severe injuries and higher mortality rates in men than women. The much higher level of 17β-estradiol (E₂) in female is one of the significant reasons for better sepsis resistance ability. Trained immunity is a novel way to fight against infection by improving innate immunity. However, whether β-glucan-induced trained immunity can promote macrophage phagocytosis to clear infections in early sepsis has not been clarified. And whether E₂ involved in this process needs further investigation. Symptoms among male, female and ovariectomized (OVX) C57BL/6 mice in early sepsis were detected. The effect of trained immunity on macrophage LC3B-associated phagocytosis (LAP) and the mechanism of E₂ functioned in this process have also been explored. We demonstrated compared with male mice, female has significantly more mild symptoms and more reactive oxygen species (ROS) production and stronger NADPH oxidase 2 (NOX2) expression in the macrophage of major organs. In contrary, these characteristics are disappeared in OVX mice. Furthermore, in macrophage cell lines and primary bone marrow- derived macrophages (BMDMs), β-glucan-induced trained immunity can increase ROS production by activating NOX2 to promote macrophage LAP. E₂ can up-regulate RUBICON through estrogen receptor α (ERα) to further facilitate macrophage LAP. These results indicated that trained immunity can improve sepsis resistance ability by stimulating macrophage LAP. E₂ can boost ROS production and RUBICON expression to further promote macrophage LAP, which can provide a new perspective to recognize the mechanism of trained immunity in gender differences when responding to sepsis.     

House dust mite allergen Der f 1 can induce the activation of latent TGF-β via its protease activity

A major house dust mite allergen Der f 1 belongs to the papain-like cysteine protease family. This study investigated whether Der f 1 can cleave the latency-associated peptide (LAP) of transforming growth factor (TGF)-β via its proteolytic activity and activate latent TGF-β. We found that Der f 1 can cleave LAP and induce the activation of latent TGF-β, leading to functional Smad signaling. Importantly, these actions of Der f 1 were inhibited by cysteine protease inhibitor E64 or inactivation of the protease activity by heat. Thus, latent TGF-β may be a direct target of Der f 1 protease activity.     

Uncoupling of IL-6 signaling and LC3-associated phagocytosis drives immunoparalysis during sepsis

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Recent insight into intermediate filament structure

Intermediate filaments (IFs) are key players in multiple cellular processes throughout human tissues. Their biochemical and structural properties are important for understanding filament assembly mechanisms, for interactions between IFs and binding partners, and for developing pharmacological agents that target IFs. IF proteins share a conserved coiled-coil central-rod domain flanked by variable N-terminal ‘head’ and C-terminal ‘tail’ domains. There have been several recent advances in our understanding of IF structure from the study of keratins, glial fibrillary acidic protein, and lamin. These include discoveries of (i) a knob–pocket tetramer assembly mechanism in coil 1B; (ii) a lamin-specific coil 1B insert providing a one-half superhelix turn; (iii) helical, yet flexible, linkers within the rod domain; and (iv) the identification of coil 2B residues required for mature filament assembly. Furthermore, the head and tail domains of some IFs contain low-complexity aromatic-rich kinked segments, and structures of IFs with binding partners show electrostatic surfaces are a major contributor to complex formation. These new data advance the connection between IF structure, pathologic mutations, and clinical diseases in humans.     

Cell-surface anchoring of Listeria adhesion protein on L. monocytogenes is fastened by internalin B for pathogenesis

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Hepatocytes Deficient in Nuclear Envelope Protein Lamina-associated Polypeptide 1 are an Ideal Mammalian System to Study Intranuclear Lipid Droplets

Lipid droplets (LDs) are generally considered to be synthesized in the ER and utilized in the cytoplasm. However, LDs have been observed inside nuclei in some cells, although recent research on nuclear LDs has focused on cultured cell lines. To better understand nuclear LDs that occur in vivo, here we examined LDs in primary hepatocytes from mice following depletion of the nuclear envelope protein lamina-associated polypeptide 1 (LAP1). Microscopic image analysis showed that LAP1-depleted hepatocytes contain frequent nuclear LDs, which differ from cytoplasmic LDs in their associated proteins. We found type 1 nucleoplasmic reticula, which are invaginations of the inner nuclear membrane, are often associated with nuclear LDs in these hepatocytes. Furthermore, in vivo depletion of the nuclear envelope proteins lamin A and C from mouse hepatocytes led to severely abnormal nuclear morphology, but significantly fewer nuclear LDs than were observed upon depletion of LAP1. In addition, we show both high-fat diet feeding and fasting of mice increased cytoplasmic lipids in LAP1-depleted hepatocytes but reduced nuclear LDs, demonstrating a relationship of LD formation with nutritional state. Finally, depletion of microsomal triglyceride transfer protein did not change the frequency of nuclear LDs in LAP1-depleted hepatocytes, suggesting that it is not required for the biogenesis of nuclear LDs in these cells. Together, these data show that LAP1-depleted hepatocytes represent an ideal mammalian system to investigate the biogenesis of nuclear LDs and their partitioning between the nucleus and cytoplasm in response to changes in nutritional state and cellular metabolism in vivo.     

Comparison of autophagy inducibility in various tyrosine kinase inhibitors and their enhanced cytotoxicity via inhibition of autophagy in cancer cells in combined treatment with azithromycin

Tyrosine kinase inhibitors (TKIs) induce autophagy in many types of cancer cells. We previously reported that gefitinib (GEF) and imatinib (IMA) induce autophagy in epidermal growth factor receptor (EGFR) knock-out A549 and non-BCR-ABL-expressing leukemia cell lines, respectively. This evidence suggests that TKI-induced autophagy is independent of the original target molecules. The present study compared the autophagy-inducing abilities of various TKIs, regardless of their targets, by quantitative autophagy flux assay. We established stable clones expressing the GFP-LC3-mCherry-LC3ΔG plasmid in A549, PC-9, and CAL 27 cell lines and assessed autophagy inducibility by monitoring the fluorescent ratios of GFP-LC3 to mCherry-LC3ΔG using an IncuCyte live cell imaging system during exposure to TKIs viz; GEF, osimertinib (OSI), lapatinib (LAP), lenvatinib (LEN), sorafenib (SOR), IMA, dasatinib (DAS), and tivantinib (TIV). Among these TKIs, DAS, GEF, and SOR exhibited prominent autophagy induction in A549 and PC-9 cells. In CAL 27 cells, IMA, SOR, and LEN, but not GEF, TIV, or OSI, exhibited autophagy induction. In the presence of azithromycin (AZM), which showed an inhibitory effect on autophagy flux, TKIs with prominent autophagy inducibility exhibited enhanced cytotoxicity via non-apoptotic cell death relative to effects of TKI alone. Therefore, autophagy inducibility of TKIs differed in the context of cancer cells. However, once induced, they appeared to have cytoprotective functions. Thus, blocking TKI-induced autophagy with AZM may improve the therapeutic effect of TKIs in cancer cells.