Active mTOR in Lung Epithelium Promotes Epithelial-Mesenchymal Transition and Enhances Lung Fibrosis.

The mTOR pathway is one of the key signal cascades in the pathogenesis of idiopathic pulmonary fibrosis. Previous studies have mainly focused on this pathway in the fibroblasts and/or myofibroblasts, but not in the epithelial cells. In this study, we sought to investigate the role of the mTOR pathway in lung epithelial cells in lung fibrosis. Using Sftpc-mTORSL1+IT transgenic mice, in which active mTOR is conditionally expressed in lung epithelial cells, we assessed the effects of chronically activated mTOR in lung epithelial cells on lung phenotypes as well as bleomycin-induced lung fibrosis. Furthermore, we isolated alveolar epithelial cell type 2 from mice and performed RNA sequencing. Sftpc-mTORSL1+IT transgenic mice had no obvious abnormal findings, but, after bleomycin administration, showed more severe fibrotic changes and lower lung compliance than control mice. RNA sequencing revealed Angptl4 (angiopoietin-like protein 4) as a candidate downstream gene of the mTOR pathway. In vitro studies revealed that ANGPTL4, as well as mTOR, promoted tight junction vulnerability and epithelial-mesenchymal transition. mTOR activation in lung epithelial cells promoted lung fibrosis and the expression of ANGPTL4, a novel downstream target of the mTOR pathway, which could be related to the etiology of fibrosis.

Pleural thickening on screening chest X-rays: a single institutional study.

Although pleural thickening is a common finding on routine chest X-rays, its radiological and clinical features remain poorly characterized. Our investigation of 28,727 chest X-rays obtained from annual health examinations confirmed that pleural thickening was the most common abnormal radiological finding. In most cases (92.2%), pleural thickening involved the apex of the lung, particularly on the right side; thus, it was defined as a pulmonary apical cap. Pleural thickening was more common in males than in females and in current smokers or ex-smokers than in never smokers. The prevalence increased with age, ranging from 1.8% in teenagers to 9.8% in adults aged 60 years and older. Moreover, pleural thickening was clearly associated with greater height and lower body weight and body mass index, suggesting that a tall, thin body shape may predispose to pleural thickening. These observations allowed us to speculate about the causative mechanisms of pleural thickening that are attributable to disproportionate perfusion, ventilation, or mechanical forces in the lungs.

Rapid production of platelet-activating factor is induced by protein kinase Cα-mediated phosphorylation of lysophosphatidylcholine acyltransferase 2 protein.

Platelet-activating factor (PAF), a potent proinflammatory lipid mediator, is synthesized rapidly in response to extracellular stimuli by the activation of acetyl-CoA:lyso-PAF acetyltransferase (lyso-PAFAT). We have reported previously that lyso-PAFAT activity is enhanced in three distinct ways in mouse macrophages: rapid activation (30 s) after PAF stimulation and minutes to hours after LPS stimulation. Lysophosphatidylcholine acyltransferase 2 (LPCAT2) was later identified as a Ca(2+)-dependent lyso-PAFAT. However, the mechanism of rapid lyso-PAFAT activation within 30 s has not been elucidated. Here we show a new signaling pathway for rapid biosynthesis of PAF that is mediated by phosphorylation of LPCAT2 at Ser-34. Stimulation by either PAF or ATP resulted in PKCα-mediated phosphorylation of LPCAT2 to enhance lyso-PAFAT activity and rapid PAF production. Biochemical analyses showed that the phosphorylation of Ser-34 resulted in augmentation of Vmax with minimal Km change. Our results offer an answer for the previously unknown mechanism of rapid PAF production.

Selective inhibitors of a PAF biosynthetic enzyme lysophosphatidylcholine acyltransferase 2.

Platelet-activating factor (PAF) is a potent pro-inflammatory phospholipid mediator. In response to extracellular stimuli, PAF is rapidly biosynthesized by lyso-PAF acetyltransferase (lyso-PAFAT). Previously, we identified two types of lyso-PAFATs: lysophosphatidylcholine acyltransferase (LPCAT)1, mostly expressed in the lungs where it produces PAF and dipalmitoyl-phosphatidylcholine essential for respiration, and LPCAT2, which biosynthesizes PAF and phosphatidylcholine (PC) in the inflammatory cells. Under inflammatory conditions, LPCAT2, but not LPCAT1, is activated and upregulated to produce PAF. Thus, it is important to develop inhibitors specific for LPCAT2 in order to ameliorate PAF-related inflammatory diseases. Here, we report the first identification of LPCAT2-specific inhibitors, N-phenylmaleimide derivatives, selected from a 174,000-compound library using fluorescence-based high-throughput screening followed by the evaluation of the effects on LPCAT1 and LPCAT2 activities, cell viability, and cellular PAF production. Selected compounds competed with acetyl-CoA for the inhibition of LPCAT2 lyso-PAFAT activity and suppressed PAF biosynthesis in mouse peritoneal macrophages stimulated with a calcium ionophore. These compounds had low inhibitory effects on LPCAT1 activity, indicating that adverse effects on respiratory functions may be avoided. The identified compounds and their derivatives will contribute to the development of novel drugs for PAF-related diseases and facilitate the analysis of LPCAT2 functions in phospholipid metabolism in vivo.

[A case of tuberculosis with multiple lung nodules, abdominal lymphadenopathy, and splenomegaly].

Abdominal tuberculous lymphadenitis is very rare. We report a case of pulmonary tuberculosis showing marked abdominal lymphadenopathy and splenomegaly. A 95-year-old man was admitted to our hospital because of abnormal chest X-ray and body weight loss in last 6 months. He had low grade fever with no abdominal pain. He did not have past history of tuberculosis. Laboratory examination showed mild renal dysfunction and mild glucose intolerance. Soluble interleukin 2 recepter was highly elevated (3800 U/ml). Tumor markers, such as carcinoembryonic antigen (CEA), cytokeratin 19 fragment (CYFRA), and progastrin-releasing peptide (Pro GRP) were all within normal limit. Chest X-ray showed multiple nodules in bilateral lung fields. Chest computed tomography showed multiple nodules in bilateral lungs, especially in upper part of lungs, right hilar lymphadenopathy and upper mediastinal lymphadenopathy. Abdominal and pelvic enhanced computed tomography showed marked abdominal lymphadenopathy and splenomegaly (67 x 49 mm). Abdominal lymph nodes were hepatoduodenal (50 x 50 mm), splenic hilar (40 x 25 mm), upper paraaortic (30 x 60 mm), and small superior mesenteric (10 x 10 mm) lymph nodes. FDG-PET showed accumulation in the nodules of right lung field, right hilar lymph nodes, upper mediastinal lymph nodes, and abdominal lymph nodes. Bronchial lavage fluid (BAL) smear for acid-fast bacilli was positive, polymerase chain reaction for Mycobacterium tuberculosis was positive and acid-fast bacilli was cultured. Transbronchial lung biopsy specimen demonstrated non-specific intraalveolar organization and alveolitis. The patient was diagnosed as pulmonary tuberculosis, but about abdominal lymphadenopathy and splenomegaly we had to differentiate malignant lymphoma, and for definite diagnosis, laparotomy was necessary. But considering his age and general condition, we followed up carefully with anti-tuberculosis therapy. Pulmonary tuberculosis, abdominal lymphadenopathy and splenomegaly all showed marked improvement 4 months after starting anti-tuberculosis therapy with isoniazid, rifampicin, and ethambutol, so we clinically diagnosed abdominal tuberculous lymphadenitis and splenic tuberculosis.

Lipid component parts analysis of the hyperthermophilic sulfate-reducing archaeon Archaeoglobus fulgidus.

Archaeoglobus (A.) fulgidus is a hyperthermophilic, anaerobic, sulfate-reducing archaeon. Although the polar lipid composition of various archaea has been reported, no information has been available for A. fulgidus polar lipids. The present paper reports the results of lipid component parts analysis applied to the archaeon. Lipid component parts analysis is a simplified analytical method developed by the authors to obtain a rough outline of information about the polar lipid of a species of a microorganism. Unfractionated total lipid is subjected to several chemical degradation procedures to release lipid component parts (core lipids, glycolipid sugars and phospholipid polar head groups), which are identified by appropriate chromatography. Archaeol and caldarchaeol were found as core lipids along with an unknown core lipid. The major glycolipid sugars were galactose and mannose. A trace amount of glucose was also detected. The phosphodiester-linked polar head groups of phospholipids were inositol and ethanolamine. The presence of these lipid components is consistent with the occurrence of polar lipid-synthesizing enzymes detected by a BLAST search of the whole genome sequence of the organism. An amino group containing phospholipid was found for the first time in an archaeon other than methanogenic archaea.