Kallistatin Ameliorates Influenza Virus Pathogenesis by Inhibition of Kallikrein-Related Peptidase 1-Mediated Cleavage of Viral Hemagglutinin

Proteolytic cleavage of the hemagglutinin (HA) of influenza virus by host trypsin-like proteases is required for viral infectivity. Some serine proteases are capable of cleaving influenza virus HA, whereas some serine protease inhibitors (serpins) inhibit the HA cleavage in various cell types. Kallikrein-related peptidase 1 (KLK1, also known as tissue kallikrein) is a widely distributed serine protease. Kallistatin, a serpin synthesized mainly in the liver and rapidly secreted into the circulation, forms complexes with KLK1 and inhibits its activity. Here, we investigated the roles of KLK1 and kallistatin in influenza virus infection. We show that the levels of KLK1 increased, whereas those of kallistatin decreased, in the lungs of mice during influenza virus infection. KLK1 cleaved H1, H2, and H3 HA molecules and consequently enhanced viral production. In contrast, kallistatin inhibited KLK1-mediated HA cleavage and reduced viral production. Cells transduced with the kallistatin gene secreted kallistatin extracellularly, which rendered them more resistant to influenza virus infection. Furthermore, lentivirus-mediated kallistatin gene delivery protected mice against lethal influenza virus challenge by reducing the viral load, inflammation, and injury in the lung. Taking the data together, we determined that KLK1 and kallistatin contribute to the pathogenesis of influenza virus by affecting the cleavage of the HA peptide and inflammatory responses. This study provides a proof of principle for the potential therapeutic application of kallistatin or other KLK1 inhibitors for influenza. Since proteolytic activation also enhances the infectivity of some other viruses, kallistatin and other kallikrein inhibitors may be explored as antiviral agents against these viruses.     

Postinfectious gastrointestinal disorders following norovirus outbreaks

Background.?The US Centers for Disease Control and Prevention estimates 20.9 million norovirus infections annually in the United States. Although the acute disease burden is sizeable, emerging data suggest norovirus may be associated with chronic gastrointestinal problems. We identified known outbreaks in US military recruits and used the Defense Medical Encounter Database (DMED) to identify the risk of new onset functional gastrointestinal disorders (FGD) and gastroesophageal reflux disease (GERD). Methods.?Subjects reporting for care of acute gastroenteritis (AGE) at a military treatment clinic during 3 known norovirus outbreaks were identified. Each AGE subject was matched with up to 4 subjects with unrelated medical encounters. Medical encounter data were analyzed for the duration of military service time (or a minimum of 1 year) to assess for incident FGD or GERD. Relative risks were calculated using regression models. Results.?We identified 1718 subjects from 3 outbreaks. After controlling for important demographic covariates, the incidence of constipation, dyspepsia, and GERD was approximately 1.5-old higher (P?相似文献   

Levofloxacin-Resistant Haemophilus influenzae,Taiwan, 2004–2010

Levofloxacin resistance in Haemophilus influenzae has increased significantly in Taiwan, from 2.0% in 2004 to 24.3% in 2010 (p<0.001). Clinical and molecular investigations of 182 levofloxacin-resistant isolates revealed that the increase was mainly the result of the spread of several clones in the elderly population in different regions.     

Epidemiology and Molecular Characterization of Macrolide-Resistant Streptococcus pyogenes in Taiwan

Our multicenter nationwide surveillance data indicated that erythromycin (ERY) resistance among group A Streptococcus (GAS) isolates in Taiwan declined from 53.1% in 1998 and 2000 to 14.6% in 2002 and 2004 and 10.7% in 2006 to 2010 (P < 0.01). The present study aimed to assess the epidemiology of GAS in Taiwan and identify factors associated with ERY resistance. All 127 ERY-resistant (ERY^r) isolates and 128 randomly selected ERY-susceptible (ERY^s) isolates recovered from 1998 to 2010 were emm typed. ERY^r isolates were also characterized by ERY resistance phenotype and mechanisms and pulsed-field gel electrophoresis (PFGE). Multilocus sequence typing was performed on selected ERY^r isolates. The predominant emm types in ERY^r isolates were emm22 (n = 33, 26.0%), emm12 (n = 24, 18.9%), emm4 (n = 21, 16.5%), and emm106 (n = 15, 11.8%). In ERY^s isolates, emm12 (n = 27, 21.9%), emm1 (n = 18, 14.1%), emm106 (n = 16, 12.5%), and emm11 (n = 9, 7.1%) predominated. The most common ERY resistance phenotype was the M phenotype (resistant to macrolides) (70.9%), with all but one isolate carrying mef(A), followed by the constitutive macrolide-lincosamide-streptogramin B resistance (cMLS_B) phenotype (26.8%), with isolates carrying erm(B) or erm(TR). ERY^r isolates of the emm12-sequence type 36 (ST36) lineage with the cMLS_B phenotype were mostly present before 2004, while those of the emm22-ST46 lineage with the M phenotype predominated in later years. Recovery from respiratory (throat swab) specimens was an independent factor associated with ERY resistance. emm1 and emm11 GAS isolates were significantly associated with ERY^s, while emm22 was detected only in ERY^r GAS. In addition, emm106 isolates were prevalent among the abscess/pus isolates, whereas emm12 isolates were strongly associated with a respiratory (throat) origin. In addition to identifying factors associated with ERY resistance in GAS, our study provides helpful information on the changing GAS epidemiology in Taiwan.     

Retrovirus-mediated transfer of prothymosin gene inhibits tumor growth and prolongs survival in murine bladder cancer

To explore the potential use of prothymosin alpha(ProT), a putative thymic hormone, in gene therapy for bladder cancer, we generated a replication-defective recombinant retroviral vector encoding ProT and tested its antitumor effect on the MBT-2 murine bladder cancer. C3H/HeN mice injected with MBT-2 cells in conjunction with retroviruses encoding ProT exhibited smaller tumor mass, lower tumor incidence and higher survival rate, as well as higher antitumor cytotoxic activities compared with those injected with control viruses. However, such effects were not observed in severe combined immunodeficiency mice, suggesting that ProT exerts antitumor effects through its immunomodulatory activities. Cell growth in monolayer culture and colony formation in soft agar were enhanced in ProT gene-modified MBT-2 clones, and such growth-promoting activities of ProT could be reversed if its nuclear localization signal (NLS) was deleted. To circumvent the proliferation-promoting effect of ProT on tumor cells, a retroviral vector encoding ProT lacking NLS was constructed. Our results showed that retroviruses encoding NLS-deleted ProT was more efficacious than those encoding wild-type ProT in prolonging survival of tumor-bearing mice. This is the first report indicating that ProT, in particular NLS-deleted ProT, delivered by retroviral vectors may be further explored for the treatment of bladder cancer.     

Role of viral infections in asthma and chronic obstructive pulmonary disease

Substantial evidence implicates common respiratory viral infections in the pathogenesis of asthma and chronic obstructive pulmonary disease (COPD). Children who experience recurrent virally induced wheezing episodes during infancy are at greater risk for developing asthma. In addition, respiratory viral infections are a major trigger for acute exacerbations of both asthma and COPD. Despite the importance of viral infections in asthma and COPD, the mechanisms by which viruses predispose to, or cause exacerbations of, these diseases remain poorly understood. It is clear that viral infections lead to enhanced airway inflammation and can cause airways hyperresponsiveness. The epithelial cell is the principal site of viral infection in the airways and plays a central role in viral modulation of airway inflammation via release of a variety of cytokines, chemokines, and growth factors. The mechanisms by which viral infections modulate epithelial function, therefore, is a topic of intense investigation. The epithelium also contributes to the host innate defense response to viral infection by releasing products that are antiviral and/or can lead to increased recruitment of dendritic cells and lymphocytes. Some evidence supports a role for the epithelial cell in specific immunity, although the response of more conventional cells of the immune system to viral infections is likely the dominant factor in this regard. Although current therapies may help combat virally induced disease exacerbations, they are less than ideal. A better understanding of the mechanisms underlying viral modulation of these diseases, therefore, may lead to new therapeutic approaches.     

IL‐25 exhibits disparate roles during Th2‐cell differentiation versus effector function

A keenly sought therapeutic approach for the treatment of allergic disease is the identification and neutralization of the cytokine that regulates the differentiation of T helper 2 (Th2) cells. Th2 cells are exciting targets for asthma therapies. Recently, the cytokine IL‐25 has been shown to enhance Th2‐type immune activity and play important roles in mediating allergic inflammatory responses. To investigate this further, we crossed IL‐25^?/? C57BL/6 mice with G4 IL‐4 C57BL/6 reporter mice and developed an assay for in vitro and in vivo IL‐4‐independent Th2‐cell differentiation. These assays were used to determine whether IL‐25 was critical for the formation of Th2 cells. We found there was no physiological role for IL‐25 in either the differentiation of Th2 cells or their development to effector or memory Th2‐cell subsets. Importantly, this data challenges the newly found and growing status of the cytokine IL‐25 and its proposed role in promoting Th2‐cell responses.     

Over‐expression of prothymosin‐α antagonizes TGFβ signalling to promote the development of emphysema

Emphysema, a major consequence of chronic obstructive pulmonary disease (COPD), is characterized by the permanent airflow restriction resulting from enlargement of alveolar airspace and loss of lung elasticity. Transforming growth factor‐β (TGFβ) signalling regulates the balance of matrix metalloproteinase (MMP)/tissue inhibitor of matrix metalloproteinase (TIMP) to control matrix homeostasis. Patients with COPD have dysregulated TGFβ signalling and reduced histone deacetylase (HDAC) activity through epigenetic up‐regulation of histone acetylation in the promoters of pro‐inflammatory genes. However, the potential link between decreased HDAC activity and dysregulated TGFβ signalling in emphysema pathogenesis remains to be determined. Prothymosin α (ProT), a highly conserved acidic nuclear protein, plays a role in the acetylation of histone and non‐histone proteins. The aim of this study was to test the hypothesis that ProT inhibits TGFβ–Smad signalling through Smad7, thereby contributing to emphysema pathogenesis. We show that ProT enhances Smad7 acetylation by decreasing its association with HDAC and thereby down‐regulates TGFβ–Smad signalling. ProT caused an imbalance between MMP and TIMP through acetylated Smad7 in favour of MMP expression. In addition to interfering with R‐Smad activation and targeting receptors for degradation in the cytoplasm, acetylated Smad7 potentiated by ProT competitively antagonized binding of the pSmad2/3–Smad4 complex to the TIMP‐3 promoter, resulting in reduced TIMP‐3 expression. These effects were detected in ProT‐over‐expressing cells, lungs of ProT transgenic mice displaying an emphysema phenotype and in emphysema patients. Importantly, increased Smad7 and reduced TIMP‐3 were found in the lungs of emphysema patients and mice with cigarette smoke extract (CSE)‐induced emphysema. Such effects could be abrogated by silencing endogenous ProT expression. Collectively, our results uncover acetylated Smad7 regulated by ProT as an important determinant in dysregulated TGFβ signalling that contributes to emphysema pathogenesis. Copyright © 2015 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.