A Protective Role of Canonical Wnt/ß-Catenin Pathway in Pathogenic Bacteria-Induced Inflammatory Responses.

Inflammation is a complex host defensive response against various disease-associated pathogens. A baseline extent of inflammation is supposed to be tightly associated with a sequence of immune-modulated processes, resulting in the protection of the host organism against pathogen invasion; however, as a matter of fact is that an uncontrolled inflammatory cascade is the main factor responsible for the host damage, accordingly suggesting a significant and indispensable involvement of negative feedback mechanism in modulation of inflammation. Evidence accumulated so far has supported a repressive effect of the canonical Wnt/ß-catenin pathway on microbial-triggered inflammation via diverse mechanisms, although that consequence is dependent on the cellular context, types of stimuli, and cytokine environment. It is of particular interest and importance to comprehend the precise way in which the Wnt/ß-catenin pathway is activated, due to its essential anti-inflammatory properties. It is assumed that an inflammatory milieu is necessary for initiating and activating this signaling, implying that Wnt activity is responsible for shielding tissues from overwhelming inflammation, thus sustaining a balanced physiological condition against bacterial infection. This review gathers the recent efforts to elucidate the mechanistic details through how Wnt/ß-catenin signaling modulates anti-inflammatory responses in response to bacterial infection and its interactions with other inflammatory signals, which warrants further study for the development of specific interventions for the treatment of inflammatory diseases. Further clinical trials from different disease settings are required.

Peptide YY inhibits transcription and replication of hepatitis B virus by suppressing promoter/enhancer activity.

Hepatitis B virus (HBV) infection is a noteworthy cause of liver diseases, especially cirrhosis and hepatocellular carcinomas. However, the interaction between the host and HBV has not been fully elucidated. Peptide YY (PYY) is a 36-amino-acid gastrointestinal hormone that is mainly involved in the regulation of the human digestive system. This study found that PYY expression was reduced in HBV-expressing hepatocytes and HBV patients. Overexpression of PYY could significantly inhibit HBV RNA, DNA levels, and the secretion of HBsAg. In addition, PYY inhibits HBV RNA dependent on transcription through reducing the activities of CP/Enh I/II, SP1 and SP2. Meanwhile, PYY blocks HBV replication independent on core, polymerase protein and ε structure of pregenomic RNA. These results suggest that PYY can impair HBV replication by suppressing viral promoters/enhancers in hepatocytes. Our data shed light on a novel role for PYY as anti-HBV restriction factor.

MicroRNA-106a Inhibits Autophagy Process and Antimicrobial Responses by Targeting ULK1, ATG7, and ATG16L1 During Mycobacterial Infection.

Autophagy is a key element of innate immune response against invading pathogens including Mycobacterium tuberculosis (M. tuberculosis). The emerging roles of microRNAs in regulating host antimicrobial responses against M. tuberculosis have gained widespread attention. However, the process by which miRNAs specifically influence antibacterial autophagy during mycobacterial infection is largely uncharacterized. In this study, we demonstrate a novel role of miR-106a in regulating macrophage autophagy against M. tuberculosis. H37Ra infection leads to downregulation of miR-106a in a time- and dose-dependent manner and concomitant upregulation of its three targets (ULK1, ATG7, and ATG16L1) in THP-1 macrophages. MiR-106a could inhibit autophagy activation and antimicrobial responses to M. tuberculosis by targeting ULK1, ATG7, and ATG16L1. Overexpression of miR-106a dramatically inhibited H37Ra-induced activation of autophagy in human THP-1 macrophages, whereas inhibitors of miR-106a remarkably promoted H37Ra-induced autophagy. The inhibitory effect of miR-106a on autophagy process during mycobacterial infection was also confirmed by Transmission Electron Microscope (TEM) observation. More importantly, forced expression of miR-106a increased mycobacterial survival, while transfection with miR-106a inhibitors attenuated the survival of intracellular mycobacteria. Taken together, these data demonstrated that miR-106a functioned as a negative regulator in autophagy and antimicrobial effects by targeting ULK1, ATG7, and ATG16L1 during M. tuberculosis infection, which may provide a potential target for developing diagnostic reagents or antibacterials against tuberculosis.

MiR-758-3p suppresses proliferation, migration and invasion of hepatocellular carcinoma cells via targeting MDM2 and mTOR.

Hepatocelluar carcinoma (HCC) is one of the most frequently diagnosed cancers worldwide and among the leading causes of cancer-related death. Although deregulation of microRNAs has been frequently described in HCC, imperfection is known about the precise molecular mechanisms by which microRNAs modulate the process of tumorogenesis and behavior of cancer cells. In this study, we demonstrated that miR-758-3p could suppress cell proliferation, migration and invasion in hepatocellular carcinoma cells. We screened and identified two novel miR-758-3p targets, MDM2 and mTOR. Up-regulation of miR-758-3p could specifically and markedly down-regulate the expression of MDM2 and mTOR. Additionally, miR-758-3p over-expression displayed significant suppression in HCC development. To identify the mechanisms, we further investigated the P53 and mTOR pathway and found that p-p70S6 kinase(Ser371), p-p70 S6 kinase(Thr389) and p-4E-BP1were dramatically down-regulated after miR-758-3p transfection, while an enhanced expression of P53, AKT and PRAS40 were visualized, thus suggesting that the role of miR-758-3p in HCC progression may be associated with MDM2-p53 and mTOR signaling pathways. Collectively, our results indicate that miR-758-3pserves as a tumor suppressor and plays a crucial role in inhibiting the proliferation, migration and invasion of HCC via targeting MDM2 and mTOR and implicate its potential application in cancer therapy.

A ROS-dependent and Caspase-3-mediated apoptosis in sheep bronchial epithelial cells in response to Mycoplasma Ovipneumoniae infections.

Mycoplasma Ovipneumoniae (M. ovipneumoniae) is a primary etiological agent of enzootic pneumonia in sheep and goats. It can enter and colonize ovine respiratory epithelial cells to establish an infection, which leads a serious cell death of epithelial cells. However, the nature of the interaction between pathogen of M. ovipneumoniae and host cells in the cell injury is currently not well understood. In this study, we investigated the epithelial cell apoptosis caused by an infection of M. ovipneumoniae in sheep primary air-liquid interface (ALI) epithelial cultures. The results showed that M. ovipneumoniae could specifically bind to ciliated cells at early stage of infection. Flow cytometric analysis demonstrated that an infection of M. ovipneumoniae induced a time-dependent cell apoptotic cell death, accompanied with an increased production of extracellular nitric oxide (NO), intracellular reactive oxygen species (ROS) production and activation of caspase-3 signaling in sheep bronchial epithelial cells. The induced cell apoptosis was further confirmed by a transferase-mediated deoxyuridine triphosphate-biotin nick end-labeling (TUNEL) assay. Interestingly, the M. ovipneumoniae-induced apoptosis and activation of caspase-3 were correlated with the production of ROS but not NO. Mechanistically, M. ovipneumoniae-induced cell apoptosis was mediated by a mechanism by increasing the expression of phosphorylation of p38 and pro-apoptotic proteins, and activating caspase-3, caspase-8 and poly ADP-ribose polymerase (PARP) cleavage. These results suggest a ROS-dependent and caspase-3-mediated cell apoptosis in sheep bronchial epithelial cells in response to M. ovipneumoniae infections.

Capsular Polysaccharide is a Main Component of Mycoplasma ovipneumoniae in the Pathogen-Induced Toll-Like Receptor-Mediated Inflammatory Responses in Sheep Airway Epithelial Cells.

Mycoplasma ovipneumoniae (M. ovipneumoniae) is characterized as an etiological agent of primary atypical pneumonia that specifically infects sheep and goat. In an attempt to better understand the pathogen-host interaction between the invading M. ovipneumoniae and airway epithelial cells, we investigated the host inflammatory responses against capsular polysaccharide (designated as CPS) of M. ovipneumoniae using sheep bronchial epithelial cells cultured in an air-liquid interface (ALI) model. Results showed that CPS derived from M. ovipneumoniae could activate toll-like receptor- (TLR-) mediated inflammatory responses, along with an elevated expression of nuclear factor kappa B (NF-κB), activator protein-1 (AP-1), and interferon regulatory factor 3 (IRF3) as well as various inflammatory-associated mediators, representatively including proinflammatory cytokines, such as IL1ß, TNFα, and IL8, and anti-inflammatory cytokines such as IL10 and TGFß of TLR signaling cascade. Mechanistically, the CPS-induced inflammation was TLR initiated and was mediated by activations of both MyD88-dependent and MyD88-independent signaling pathways. Of importance, a blockage of CPS with specific antibody led a significant reduction of M. ovipneumoniae-induced inflammatory responses in sheep bronchial epithelial cells. These results suggested that CPS is a key virulent component of M. ovipneumoniae, which may play a crucial role in the inflammatory response induced by M. ovipneumoniae infections.

Capsular Polysaccharide of Mycoplasma ovipneumoniae Induces Sheep Airway Epithelial Cell Apoptosis via ROS-Dependent JNK/P38 MAPK Pathways.

In an attempt to better understand the pathogen-host interaction between invading Mycoplasma ovipneumoniae (M. ovipneumoniae) and sheep airway epithelial cells, biological effects and possible molecular mechanism of capsular polysaccharide of M. ovipneumoniae (CPS) in the induction of cell apoptosis were explored using sheep bronchial epithelial cells cultured in air-liquid interface (ALI). The CPS of M. ovipneumoniae was first isolated and purified. Results showed that CPS had a cytotoxic effect by disrupting the integrity of mitochondrial membrane, accompanied with an increase of reactive oxygen species and decrease of mitochondrial membrane potential (ΔΨm). Of importance, the CPS exhibited an ability to induce caspase-dependent cell apoptosis via both intrinsic and extrinsic apoptotic pathways. Mechanistically, the CPS induced extrinsic cell apoptosis by upregulating FAS/FASL signaling proteins and cleaved-caspase-8 and promoted a ROS-dependent intrinsic cell apoptosis by activating a JNK and p38 signaling but not ERK1/2 signaling of mitogen-activated protein kinases (MAPK) pathways. These findings provide the first evidence that CPS of M. ovipneumoniae induces a caspase-dependent apoptosis via both intrinsic and extrinsic apoptotic pathways in sheep bronchial epithelial cells, which may be mainly attributed by a ROS-dependent JNK and p38 MAPK signaling pathways.

Mycoplasma ovipneumoniae induces sheep airway epithelial cell apoptosis through an ERK signalling-mediated mitochondria pathway.

BACKGROUND: Mycoplasma ovipneumoniae (M. ovipneumoniae) is a species of Mycoplasma bacteria that specifically infects sheep and goat, causing ovine infectious pleuropneumonia. However, the mechanism underlying the pathogen-host interaction between M. ovipneumoniae and airway epithelial cells is unknown. METHODS: A primary air-liquid interface (ALI) epithelial culture model generated from the bronchial epithelial cells of Ningxia Tan sheep (ovis aries) was employed to explore the potential mechanism of M. ovipneumoniae-induced cell apoptosis by characterizing the production of reactive oxygen species (ROS), methane dicarboxylic aldehyde (MDA) and anti-oxidative enzymes, as well as the mitochondrial membrane potentials, cytochrome C release, and activities of ERK and caspase signalling pathways. RESULTS: Increased ROS production and MDA concentration with mitochondrial membrane dysfunction and apoptotic cell death but decreased expression of the antioxidant enzymes catalase (CAT), glutathione synthetase (GSS), total superoxide dismutaes (T-SOD) and Mn-SOD were observed in sheep airway epithelial cells infected with M. ovipneumoniae. Mechanistically, the M. ovipneumoniae-induced cell apoptosis and disruption of mitochondrial integrity reflected mechanisms by which pathogen-activated mitogen-activated protein kinase (MAPK) signalling sequentially led to mitochondrial damage and release of Cyt-C into the cytoplasm, which in turn triggered the activation of caspase signalling cascade, resulting in the apoptosis of host cells. CONCLUSIONS: These results suggest that M. ovipneumoniae-induced ROS and MAPK signalling-mediated mitochondrial apoptotic pathways might play key roles in the pathogenesis of M. ovipneumoniae infection in sheep lungs.

[Mutation and expression of WNT8b gene and SHH gene in Hirschsprung disease].

OBJECTIVE: To investigate the relationship of WNT8b and SHH genes mutation and Hirschsprung disease(HSCR) in Chinese children. METHODS: Preoperative whole blood preparations in 72 children with sporadic HSCR from northeast China were collected(study group). Seventy-two healthy children were used as controls(matched for sex and age). Genomic DNA was obtained from peripheral blood. Exon 1 of WNT8b gene and the exon 1 of SHH gene were analyzed for gene mutation. The mutation products were automatically sequenced. The levels of WNT8b and SHH mRNA were detected by quantitative real-time PCR(qRT-PCR) in blood samples. RESULTS: On sequencing, 13 out of 72 children with HSCR had WNT8b gene mutation in the coding area, including heterozygosity deletion in 8 cases (11.1%) and base replacement in 5(6.9%). Eleven children with HSCR had SHH gene mutation in the coding area including heterozygosity deletion in 7 cases(9.7%) and base replacement in 4(5.6%). No mutations in WNT8b and SHH genes were found in the control group. The WNT8b and SHH mRNA levels were different between the study group and the control group(30.01±1.13 vs. 17.33±0.62, and 28.25±1.27 vs. 18.94±0.31, P<0.05). CONCLUSIONS: WNT8b and SHH mutations and abnormal expressions are present in the peripheral blood of children with sporadic HSCR. These two genes may be related to the development of sporadic HSCR in children in the northeastern China.