Mst1-FoxO Signaling Protects Naïve T Lymphocytes from Cellular Oxidative Stress in Mice

Background: The Ste-20 family kinase Hippo restricts cell proliferation and promotes apoptosis for proper organ development in Drosophila. InC. elegans, Hippo homolog also regulates longevity. The mammalian Ste20-like protein kinase, Mst1, plays a role in apoptosis induced by various types of apoptotic stress. Mst1 also regulates peripheral naïve T cell trafficking and proliferation in mice. However, its functions in mammals are not fully understood. Methodology/Principal Findings: Here, we report that the Mst1-FoxO signaling pathway plays a crucial role in survival, but not apoptosis, of naïve T cells. In Mst1 2/2 mice, peripheral T cells showed impaired FoxO1/3 activation and decreased FoxO protein levels. Consistently, the FoxO targets, Sod2 and catalase, were significantly down-regulated in Mst1 2/2 T cells, thereby resulting in elevated levels of intracellular reactive oxygen species (ROS) and induction of apoptosis. Expression of constitutively active FoxO3a restored Mst1 2/2 T cell survival. Crossing Mst1 transgenic mice (Mst1 Tg) with Mst1 2/2 mice reduced ROS levels and restored normal numbers of peripheral naïve T cells in Mst1 Tg;Mst1 2/2 progeny. Interestingly, peripheral T cells from Mst1 2/2 mice were hypersensitive to c-irradiation and paraquat-induced oxidative stresses, whereas those from Mst1 Tg mice were resistant. Conclusions/Significance: These data support the hypothesis that tolerance to increased levels of intracellular RO

Melatonin restores Muc2 depletion induced by V. vulnificus VvpM via melatonin receptor 2 coupling with Gαq

Background Melatonin (5-methoxy-N-acetyltryptamine), a hormone produced in the pineal gland, has a variety of biological functions as an antioxidant, but a functional role of melatonin in the regulation of intestinal mucin (Muc) production during bacterial infection has yet to be described in detail. In this study, we investigate the effects of melatonin during Muc2 repression elicited by the Gram-negative bacterium V. vulnificus. Methods Mucus-secreting human HT29-MTX cells were used to study the functional role of melatonin during Muc2 depletion induced by the recombinant protein (r) VvpM produced by V. vulnificus. The regulatory effects of melatonin coupling with melatonin receptor 2 (MT2) on the production of reactive oxygen species (ROS), the activation of PKCδ and ERK, and the hypermethylation of the Muc2 promoter as induced by rVvpM were examined. Experimental mouse models of V. vulnificus infection were used to study the role of melatonin and how it neutralizes the bacterial toxin activity related to Muc2 repression. Results Recombinant protein (r) VvpM significantly reduced the level of Muc2 in HT29-MTX cells. The repression of Muc2 induced by rVvpM was significantly restored upon a treatment with melatonin (1 μM), which had been inhibited by the knockdown of MT2 coupling with Gαq and the NADPH oxidase subunit p47 phox. Melatonin inhibited the ROS-mediated phosphorylation of PKCδ and ERK responsible for region-specific hypermethylation in the Muc2 promoter in rVvpM-treated HT29-MTX cells. In the mouse models of V. vulnificus infection, treatment with melatonin maintained the level of Muc2 expression in the intestine. In addition, the mutation of the VvpM gene from V. vulnificus exhibited an effect similar to that of melatonin. Conclusions These results demonstrate that melatonin acting on MT2 inhibits the hypermethylation of the Muc2 promoter to restore the level of Muc2 production in intestinal epithelial cells infected with V. vulnificus.This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (NRF-2016R1D1A1B03930458)

A case of hemocholecyst associated with hemobilia following radiofrequency ablation therapy for hepatocellular carcinoma

Radiofrequency ablation (RFA) is performed as an alternative to surgical resection for primary or secondary liver malignancies. Although RFA can be performed safely in most patients, early and late complications related to mechanical or thermal damage occur in 8-9.5% cases. Hemocholecyst, which refers to hemorrhage of the gallbladder, has been reported with primary gallbladder disease or as a secondary event associated with hemobilia. Hemobilia, defined as hemorrhage in the biliary tract and most commonly associated with accidental or iatrogenic trauma, is a rare complication of RFA. Here we report a case of hemocholecyst associated with hemobilia after RFA for hepatocellular carcinoma that was successfully managed by laparoscopic cholecystectomy

Neutrophil extracellular traps and heparin-induced antibodies contribute to vascular access thrombosis in hemodialysis patients

Background Anti-heparin/platelet factor 4 (PF4) antibodies may trigger severe thrombotic complications in hemodialysis (HD) patients. Tetrameric PF4 has a high affinity for extracellular DNA, which is a key component of neutrophil extracellular traps (NETs); therefore, the interactions between anti-heparin/PF4 antibodies and NETs can contribute to prothrombotic events. Methods Anti-heparin/PF4 antibody levels were measured by enzyme-linked immunosorbent assay and an optical density > 1.8 was regarded as clinically significant. We additionally measured serum nucleosome levels as representative markers of NETs, and the contributions of anti-heparin/PF4 and increased serum nucleosome levels to the primary functional patency loss of vascular access was assessed. Results The frequency of anti-heparin/PF4 antibodies was significantly higher in incident HD patients compared to prevalent HD patients (23.6% vs. 7.7%). Serum nucleosome levels, as well as the white blood cell counts, neutrophil counts, and high- sensitivity C-reactive protein levels, were significantly higher in anti-heparin/PF4 antibody-positive patients compared to the control. Platelet counts tended to be lower in the patients with anti-heparin/PF4 of >1.8 than in the controls. Relative risk calculations showed that the presence of anti-heparin/PF4 antibodies increased the risk of primary functional patency failure by 4.28-fold, and this risk increased further with higher nucleosome levels. Furthermore, in the anti-heparin/PF4 antibody-positive group, the time to first vascular intervention was much shorter, and the risk of repeated intervention was higher, compared to the controls. Conclusion In incident HD patients, the presence of anti-heparin/PF4 antibodies was associated with increased NET formation; this could be a strong predictor of vascular access complication

A Case of Amblyomma testudinarium Tick Bite in a Korean Woman

A case of tick bite was found in the inguinal region of a 74-year-old Korean woman. She was attacked by the tick while working in her vegetable garden in the vicinity of mountain located in Suncheon City, the southern coastal area of the Korean Peninsula. On admission she complained of mild discomfort and itching around the bite area. The causative tick was 23 mm long and had slender pedipalps. The scutum was quite ornate and had eyes at the edge. The genital aperture was located anterior to the level of the coxa II. The spiracular plate was comma-shaped and the anus was surrounded posteriorly by the anal groove. The coxa I had subequal 2 spurs; the external one slightly larger. The spur of coxa IV was slightly longer than those of coxae II and III. The tarsus IV had 2 distinct subapical ventral spurs. It was identified as the fully engorged adult female of Amblyomma testudinarium. This is the first human case of Amblyomma bite in Korea

Nasal commensal Staphylococcus epidermidis enhances interferon-λ-dependent immunity against influenza virus

Background Staphylococcus epidermidis is one of the most abundant colonizers of healthy human mucosa including that in the respiratory tract. As the respiratory microbiome has been linked to host immune responses, this study sought to determine the role of nasal mucosa-associated S. epidermidis in innate immune responses against the influenza A virus (IAV). S. epidermidis strains were isolated from nasal mucus samples of healthy individuals. The effects of these mucosa-derived commensal strains on interferon (IFN)-dependent innate immunity and IAV infection dynamics were tested in vitro using normal human nasal epithelial (NHNE) cells and human turbinate mucosa. The effects of S. epidermidis on antiviral immunity were also tested in vivo using an acute IAV infection mouse model. Results Exposure of NHNE cells to nasal mucosa-derived S. epidermidis increased IFN-λ mRNA and secreted protein levels in the absence of viral stimulation. In the context of IAV infection, NHNE exposure to S. epidermidis prevented an increase in the viral burden, as revealed by IAV PA mRNA abundance, IAV nucleoprotein levels, and viral titers. S. epidermidis also enhanced transcription of IFN-stimulated genes independently of Toll-like receptor 2 and further induced IFN-λ production in IAV-infected cells by promoting phosphorylation of interferon regulatory factor 7. In a murine infection model, S. epidermidis prevented the spread of IAV to the lungs by stimulating IFN-λ innate immunity and suppressing IAV replication in the nasal mucosa. Conclusion The human nasal commensal S. epidermidis mediates front-line antiviral protection against IAV infection through modulation of IFN-λ-dependent innate immune mechanisms in the nasal mucosa, thereby demonstrating the role of host-bacterial commensalism in shaping human antiviral responses.This work was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Kim et al. Microbiome (2019) 7:80 Page 10 of 12 Education (2016R1D1A1B01014116 to H.J.K.) and (2017M3A9F3041233 to S.S.Y.). This research was supported by a grant of the Korea Health Technology R&D Project through the Korea Health Industry Development Institute (KHIDI), funded by the Ministry of Health & Welfare, Republic of Korea (HI18C1337 to H.J.K), and the Bio & Medical Technology Development Program of the National Research Foundation (NRF) funded by the Ministry of Science, ICT & Future Planning (NRF-2014M3A9D5A01073865 to J.Y.C

Melatonin activates ABCA1 via the BiP/NRF1 pathway to suppress high-cholesterol-induced apoptosis of mesenchymal stem cells

Abstract Background Retarded wound healing in patients with obesity contributes to a risk of complications associated with vascular insufficiency and oxidative stress. The high cholesterol levels of patients with obesity are associated with apoptosis of engrafted umbilical cord blood-derived mesenchymal stem cells (UCB-MSCs). Melatonin contributes to the prevention of cholesterol accumulation in patients with obesity via a mechanism that is poorly understood. We therefore investigated the regulatory mechanism of melatonin in cholesterol-induced apoptosis. Methods The protective effects of melatonin on cholesterol-induced apoptosis were investigated in UCB-MSCs. We used a mouse model of induced obesity to show that melatonin treatment restored the survival rate of transplanted UCB-MSCs and their wound-healing capacity. The mean values of the treatment groups were compared with those of the control group using Students t test, and differences among three or more groups were analyzed using one-way analysis of variance with Dunnetts multiple comparison test. Results Melatonin treatment increased the expression of ATP-binding cassette subfamily A member 1 (ABCA1), which reduced cholesterol accumulation and cholesterol-induced apoptosis. The mouse skin wound healing model showed that melatonin treatment restored the survival rate of transplanted UCB-MSCs and the wound-healing capacity of obese mice. Melatonin inhibited the expression of binding immunoglobulin protein (BiP) through the regulation of MT2/Sp1-dependent microRNA-597-5p. Melatonin decreased the co-localization of BiP with nuclear factor erythroid 2-related factor 1 (NRF1), which resulted in increased ABCA1 expression. Conclusion Melatonin induced the efflux of intracellular cholesterol through ABCA1 to decrease apoptosis of UCB-MSCs via an MT2-dependent BiP/NRF1 pathway