Changting Liu

Molecular pathogenesis of Klebsiella pneumoniae

Typical Klebsiella pneumoniae is an opportunistic pathogen, which mostly affects those with weakened immune systems and tends to cause nosocomial infections. A subset of hypervirulent K. pneumoniae serotypes with elevated production of capsule polysaccharide can affect previously healthy persons and cause life-threatening community-acquired infections, such as pyogenic liver abscess, meningitis, necrotizing fasciitis, endophthalmitis and severe pneumonia. K. pneumoniae utilizes a variety of virulence factors, especially capsule polysaccharide, lipopolysaccharide, fimbriae, outer membrane proteins and determinants for iron acquisition and nitrogen source utilization, for survival and immune evasion during infection. This article aims to present the state-of-the-art understanding of the molecular pathogenesis of K. pneumoniae.

NDM-1 encoded by a pNDM-BJ01-like plasmid p3SP-NDM in clinical Enterobacter aerogenes

A carbapenem-nonsusceptible Enterobacter aerogenes strain named 3-SP was isolated from a human case of pneumonia in a Chinese teaching hospital. NDM-1 carbapenemase is produced by a pNDM-BJ01-like conjugative plasmid designated p3SP-NDM to account for carbapenem resistance of 3-SP. p3SP-NDM was fully sequenced and compared with all publically available pNDM-BJ01-like plasmids. The genetic differences between p3SP-NDM and pNDM-BJ01 include only 18 single nucleotide polymorphisms, a 1 bp deletion and a 706 bp deletion. p3SP-NDM and pNDM-BJ01 harbor an identical Tn125 element organized as ISAba125, blaNDM−1, bleMBL, ΔtrpF, dsbC, cutA, ΔgroES, groEL, ISCR27, and ISAba125. The blaNDM−1 surrounding regions in these pNDM-BJ01-like plasmids have a conserved linear organization ISAba14-aphA6-Tn125-unknown IS, with considerable genetic differences identified within or immediately downstream of Tn125. All reported pNDM-BJ01-like plasmids are exclusively found in Acinetobacter, whereas this is the first report of identification of a pNDM-BJ01-like plasmid in Enterobacteriaceae.

Heme oxygenase-1 system, inflammation and ventilator-induced lung injury.

Mechanical ventilation is an indispensable supportive intervention for acute respiratory failure. However, mechanical ventilation can provoke ventilator-induced lung injury, which remains one of the major causes of morbidity and mortality in critically ill patients. Excessive inflammatory response characterized by infiltration of inflammatory cells and overproduction of inflammatory mediators contributes to the pathogenesis of ventilator-induced lung injury. At present, apart from the protective ventilation strategy, no other pharmacological intervention is available to attenuate ventilator-induced lung injury. Heme oxygenase-1 (HO-1) is the inducible isoform of the first and rate-limiting enzyme which degrades heme into carbon monoxide, ferritin and bilirubin. Accumulating evidence suggests that HO-1 system may function as a crucial negative regulator in the modulation of inflammatory process. This anti-inflammatory action of HO-1 is mediated essentially by the regulation of the key cells involved in inflammation and restoration of the balance between pro-inflammatory and anti-inflammatory mediators. Therefore, HO-1 system represents a promising therapeutic target for intervention of ventilator-induced lung injury.

Protective effects of hemin in an experimental model of ventilator-induced lung injury.

Mechanical ventilation is an indispensable life-support modality for critically ill patients with acute lung injury or acute respiratory distress syndrome. Unfortunately, mechanical ventilation even the protective ventilation strategies may evoke ventilator-induced lung injury. Heme oxygenase-1 (HO-1) has recently exhibited anti-inflammatory and anti-oxidative properties in vitro and in vivo. The effect of HO-1 in ventilator-induced lung injury has not been fully characterized. In this study, rabbits were subjected to high tidal volume ventilation to induce ventilator-induced lung injury, which was confirmed by histopathological alterations, increased bronchoalveolar lavage fluid protein content and lung wet-to-dry ratio. In contrast to the level of HO-1 expression in high tidal volume group, pretreatment with hemin, an inducer of HO-1, further up-regulated HO-1 expression. At the same time, these lung injury indexes were attenuated markedly. This pulmonary protection was accompanied by a decrease in bronchoalveolar lavage fluid neutrophil count and in lung myeloperoxidase activity. Besides, pretreatment with hemin prohibited the production of proinflammatory cytokines, including tumor necrosis factor (TNF)-α, interleukin (IL)-8, and up-regulated the level of anti-inflammatory cytokine interleukin (IL)-10 in bronchoalveolar lavage fluid. Furthermore, a decreased malondialdehyde activity, a marker of oxidative stress and a robust increase in total antioxidant capacity were observed in hemin-treated animals. Our findings suggest that HO-1 up-regulation by hemin plays a protective role in ventilator-induced lung injury by suppression inflammatory process and oxidative stress.

Analysis of Long Non-Coding RNA Expression Profiles in Non-Small Cell Lung Cancer

Background/Aims: Long non-coding RNAs (lncRNAs) play an important role in tumorigenesis. However, the role of lncRNA expression in human Non-small cell lung cancer (NSCLC) biology, prognosis and molecular classification remains unknown. Methods: We established the IncRNA profile in NSCLC by re-annotation of microarrays from the Gene expression omnibus database. Quantitative real-time PCR was used to determine expression of LINC00342. Results: 6066 differentially expressed IncRNAs were identified and we found a novel IncRNA, LINC00342 was significantly up-regulated in NSCLC tissues compared with normal tissues. We confirmed the over-expression of LINC00342 in a cohort of NSCLC patients and found LINC00342 expression level was positively correlated with lymph node metastasis and TNM stages. Furthermore, in a large online database of 1942 NSCLC patients, high expression of LINC00342 indicated poor Overall survival (HR = 1.28, 95% CI: 1.13-1.45) and post progression survival (HR = 1.43, 95% CI: 1.09-1.88). Bioinformatics analyses showed that LINC00342 was co-expressed with different protein-coding genes in NSCLC and normal tissues. Additionally, gene set enrichment analyses found that PTEN and P53 pathways genes were enriched in the groups with higher LINC00342 expression level. By small interfering RNAs mediated silence of LINC00342, proliferation ability was significantly inhibited in lung cancer cell line. Conclusion: To summary, our findings indicate that a set of IncRNAs are differentially expressed in NSCLC and we characterized a novel IncRNA, LINC00342 which is significantly up-regulated in NSCLC and could be a prognostic biomarker.

Urinary proteomics analysis for sepsis biomarkers with iTRAQ labeling and two-dimensional liquid chromatography-tandem mass spectrometry.

BACKGROUND Proteomics has only recently been applied to the field of critical care research. Sepsis is a major factor contributing to intensive care unit admissions and deaths. The purpose of this study was to screen potential urinary biomarkers for sepsis using A proteomics approach. METHODS Fifteen sepsis and 15 systemic inflammatory response syndrome patients were involved in this study. Urinary proteins were identified by isobaric tag for relative and absolute quantitation coupled with liquid chromatography–tandem mass spectrometry. Mass spectroscopy analysis was performed with the Mascot software and the International Protein Index. Bioinformatics analyses were performed using the hierarchy cluster analysis, the STRING software, the Gene Ontology, and the Kyoto Encyclopedia of Genes and Genome database. RESULTS One hundred thirty proteins were identified, and 34 differentially expressed proteins were selected (fold change, >1.5). On the basis of the Gene Ontology and the Kyoto Encyclopedia of Genes and Genome database, these 34 proteins were identified to be involved in inflammation, immunity, and structural or cytoskeletal processes. Five proteins were selected by a protein–protein interaction network for sepsis differentiation: cadherin 1, haptoglobin, complement 3, alpha-1-antitrypsin, and ceruloplasmin. CONCLUSION Urinary proteomics may represent a suitable approach for sepsis-related research. The detection of urinary biomarkers is expected to become a noninvasive and acceptable method, which facilitates the close surveillance of diseases and reduces medical costs. LEVELS OF EVIDENCE Diagnostic study, level IV.

Discrimination of sepsis stage metabolic profiles with an LC/MS-MS-based metabolomics approach

Background To identify metabolic biomarkers that can be used to differentiate sepsis from systemic inflammatory response syndrome (SIRS), assess severity and predict outcomes. Methods 65 patients were involved in this study, including 35 patients with sepsis, 15 patients with SIRS and 15 normal patients. Small metabolites that were present in patient serum samples were measured by liquid chromatography mass spectrometry techniques and analysed using multivariate statistical methods. Results The metabolic profiling of normal patients and patients with SIRS or sepsis was markedly different. A significant decrease in the levels of lactitol dehydrate and S-phenyl-d-cysteine and an increase in the levels of S-(3-methylbutanoyl)-dihydrolipoamide-E and N-nonanoyl glycine were observed in patients with sepsis in comparison to patients with SIRS (p<0.05). Patients with severe sepsis and septic shock displayed lower levels of glyceryl-phosphoryl-ethanolamine, Ne, Ne dimethyllysine, phenylacetamide and d-cysteine (p<0.05) in their sera. The profiles of patients with sepsis 48 h before death illustrated an obvious state of metabolic disorder, such that S-(3-methylbutanoyl)-dihydrolipoamide-E, phosphatidylglycerol (22:2 (13Z, 16Z)/0:0), glycerophosphocholine and S-succinyl glutathione were significantly decreased (p<0.05). The receiver operating characteristic curve of the differential expression of these metabolites was also performed. Conclusions The body produces significant evidence of metabolic disorder during SIRS or sepsis. Seven metabolites may potentially be used to diagnose sepsis. Trial registration number ClinicalTrial.gov identifier NCT01649440.

IMP-1 encoded by a novel Tn402-like class 1 integron in clinical Achromobacter xylosoxidans, China

Achromobacter xylosoxidans strain A22732 is isolated from a pneumonia patient in China and produces carbapenemases OXA-114e and IMP-1, which are encoded by chromosome and plasmid, respectively, and confer resistance to multiple ß-lactam antibiotics including carbapenems. The blaIMP-1 gene together with aacA7 and orfE is captured by a novel Tn402-like class 1 integron in a conjugative IncP-1ß plasmid. In addition to the intrinsic integron promoter PcW, there is still a blaIMP-1 gene cassette-specific promoter. This is the first report of carbapenemase-encoding IncP-1ß plasmid in clinical bacterial isolate.

A novel PCR-based genotyping scheme for clinical Klebsiella pneumoniae

AIM To establish a PCR-based genotyping method for clinical Klebsiella pneumoniae. MATERIALS & METHODS The prevalence of six serotype markers, 41 large variably presented gene clusters, and seven additional virulence markers were screened by PCR in 327 clinical K. pneumoniae strains from China. RESULTS Detection of serotype markers enabled the identification of capsular serotypes K1, K2, K5, K20, K54 and K57. K. pneumoniae isolates of different origins gave distinct profiles of virulence loci, allowing us to gain a full overview of virulence gene distribution of the strains tested. A novel genotyping scheme was established to group clinical K. pneumoniae strains into distinct complexes based on the profiles of large variably presented gene clusters and virulence markers. CONCLUSION This PCR-based genotyping method would be useful to not only characterize genetic diversity and virulence gene distribution, but also for genotyping, origin tracing and risk estimation of K. pneumoniae.

WWTR1 promotes cell proliferation and inhibits apoptosis through cyclin A and CTGF regulation in non-small cell lung cancer

The Hippo pathway plays a major role in development and organ size control, and its dysregulation contributes to tumorigenesis. WWTR1 is a transcription coactivator acting downstream of the Hippo pathway. Recently, WWTR1 has been reported to be overexpressed in several human cancers including lung cancer. However, the molecular mechanism of WWTR1 regulating lung cancer aggressiveness remains ambiguous. In the present study, we analyzed the expression of WWTR1 in NSCLC cell lines and found that WWTR1 was overexpressed at both the mRNA and protein levels. Knockdown of WWTR1 by siRNA interference in A549 cells significantly inhibited cell proliferation and increased paclitaxel-induced apoptosis. On the other side, WWTR1 overexpression in HBE cell line promoted cell proliferation and inhibited apoptosis. In addition, we found that the decreased proliferation after siRNA treatment was due to cell cycle arrest. Further analysis showed that WWTR1 could induce cyclin A, connective tissue growth factor (CTGF) expression, and inhibit caspase3 cleavage. In conclusion, WWTR1 promotes malignant cell growth and inhibits apoptosis by cyclin A and CTGF regulation.